Category: Quiz

Pediatric burn injury

Pediatric burn injury

Q. 1 A 3 year old child suffers from burn injury with the following body parts involved: face including scalp, both buttocks and circumferentially around both thighs. How much is TBSA involved? 

 A

0.25

 B

0.26

 C

0.35

 D

0.45

Q. 1

A 3 year old child suffers from burn injury with the following body parts involved: face including scalp, both buttocks and circumferentially around both thighs. How much is TBSA involved? 

 A

0.25

 B

0.26

 C

0.35

 D

0.45

Ans. C

Explanation:

Ans is ‘c’ i.e. 0.35 

Using Modified Lund-Browder chart:

Area

Percentage

 

Face

9

 

Scalp

9

 

Both buttocks

2.5 + 2.5 = 5

 

Both thighs circumferentially

3.5 x 2 + 3.5 x 2 =

15

Total body surface area

38

 

 [img id=10162]


Q. 2

Burns in children assessed by:     
AIIMS 13

 A

Rule of nine

 B

Lund and Browder

 C

Palmer surface method

 D

Hasse’s rule

Q. 2

Burns in children assessed by:     
AIIMS 13

 A

Rule of nine

 B

Lund and Browder

 C

Palmer surface method

 D

Hasse’s rule

Ans. B

Explanation:

Ans. Lund and Browder


Q. 3

Head and neck burns in infant constitute _____________of burns:          
Kerala 08

 A

9

 B

18

 C

24

 D

36

Q. 3

Head and neck burns in infant constitute _____________of burns:          
Kerala 08

 A

9

 B

18

 C

24

 D

36

Ans. B

Explanation:

Ans. 18

Quiz In Between
Q. 4

A 2-year-old child had burns on buttocks, both legs, face, neck and singeing of hair. Total surface area burnt:    
JIPMER 14

 A

27%

 B

37%

 C

45%

 D

55%

Q. 4

A 2-year-old child had burns on buttocks, both legs, face, neck and singeing of hair. Total surface area burnt:    
JIPMER 14

 A

27%

 B

37%

 C

45%

 D

55%

Ans. B

Explanation:

Ans. 37%


Q. 5

In a 6-year-old child with burns involving whole of head and trunk, the estimated body surface area involved:      
JIPMER 09

 A

44%

 B

48%

 C

55%

 D

58%

Q. 5

In a 6-year-old child with burns involving whole of head and trunk, the estimated body surface area involved:      
JIPMER 09

 A

44%

 B

48%

 C

55%

 D

58%

Ans. B

Explanation:

Ans. 48%


Q. 6

Parkland formula for burns is for:
Maharashtra 09; UP 09; Bihar 12

 A

Ringer lactate

 B

Glucose saline

 C

Normal saline

 D

25% dextrose

Q. 6

Parkland formula for burns is for:
Maharashtra 09; UP 09; Bihar 12

 A

Ringer lactate

 B

Glucose saline

 C

Normal saline

 D

25% dextrose

Ans. A

Explanation:

Ans. Ringer lactate

Quiz In Between


Atherosclerosis

Atherosclerosis

Q. 1 All will predispose to atherosclerosis except:

 A

Homocystinemia

 B

Fibrinogen

 C

Calcium

 D

Lipoprotein A

Q. 1

All will predispose to atherosclerosis except:

 A

Homocystinemia

 B

Fibrinogen

 C

Calcium

 D

Lipoprotein A

Ans. C

Explanation:

Q. 2

Atherosclerosis in the coronary circulation most commonly affects –

 A

Left anterior descending artery

 B

Left circumflex

 C

Right coronary

 D

All of the above

Q. 2

Atherosclerosis in the coronary circulation most commonly affects –

 A

Left anterior descending artery

 B

Left circumflex

 C

Right coronary

 D

All of the above

Ans. A

Explanation:

Ans. is ‘a’ i.e., Left anterior descending artery


Q. 3

In atherosclerosis, increased LDL in monocyte macrophage due to –

 A

LDL receptors on macrophage

 B

LDL receptors on macrophage

 C

Lipids in LDL’get oxidized

 D

Lipids in LDL’get oxidized

Q. 3

In atherosclerosis, increased LDL in monocyte macrophage due to –

 A

LDL receptors on macrophage

 B

LDL receptors on macrophage

 C

Lipids in LDL’get oxidized

 D

Lipids in LDL’get oxidized

Ans. C

Explanation:

Ans. is ‘c’ i.e., Lipids in LDL gets oxidized

Quiz In Between


Q. 4

All of the following are risk factors for atherosclerosis except :

 A Increased waist – hip ratio

 B

Hyperhomocysteinemia

 C

Decreased fibrinogen levels

 D

Decreased HDL levels

Q. 4

All of the following are risk factors for atherosclerosis except :

 A Increased waist – hip ratio

 B

Hyperhomocysteinemia

 C

Decreased fibrinogen levels

 D

Decreased HDL levels

Ans. C

Explanation:

Answer is C (Decreased fibrinogen levels)

Increased levels of .fibrinogen (and not decreased fibrinogen levels) are associated with increased risk of atherosclerosis.

  • Fibrinogen Levels

‘Fibrinogen levels correlate with coronary risk and provide information regarding coronary risk independent of lipoprotein profile. Elevated fibrinogen levels might promote a thrombotic diathesis’.

  • Waist Hip Ratio : This refers to a characteristic ‘male’ distribution of adipose tissue i.e. excess of fat in the abdomen compared with that in hips.

`An elevated waist/hip ratio has been associated with symptomatic cardiovascular disease and cerebrovascular disease in both men and women. – Pubmed (NCBI – website)

Hyperhomocvsteinemia and low HDL levels are known risk factors for Atherosclerosis (as depicted in the following table).

Major risk Factors for Atherosclerosis

  • Cigarette smoking
  • Hypertension (BP > 140/90mm/hg) or (on Antihypertensive medication)
  • Low HDL cholesterol
  • Diabetes mellitus
  • Family history of CHD
  • Age (Men > 45 years; Women > 55 years)
  • Life style risk factors Obeity (BMI > 30 kg/m2)

Physical inactivity Atherogenic diet

Emerging risk factors

  • Lipoprotein (a)
  • Homocystine             •
  • Prothrombotic factors (Fibrinogen)
  • Pro inflammatory factors
  • Impaired fasting glucose
  • Subcl inical atherogenesis

Q. 5 The amino acid which is associated with atherosclerosis is :

 A

Lysine

 B

Homocysteine

 C

Cysteine

 D

Alanine

Q. 5

The amino acid which is associated with atherosclerosis is :

 A

Lysine

 B

Homocysteine

 C

Cysteine

 D

Alanine

Ans. B

Explanation:

Answer is B (Homocysteine)

  • There is a strong positive correlation between atherosclerosis and circulating levels of Homocysteine’
  • Hyperhomocysteinemia has been most consistently linked with atherosclerosis and coronary thrombotic events
  • “Patient with clinical and angiographic evidence of coronary artery disease tend to have higher levels of plasma homocysteine. The relationship has not been extended to cerebrovascular and peripheral vascular disease”- CMDT
  • “A large body of literature suggests a relationship between hyperhomocysteinemia and coronary events. Several mutations in the enzymes involved in homocysteine accumulation correlate to thrombosis and (in some studies) coronary risk”
  • An increase of 5 micromol / L of homocysteine in serum elevates the risk of coronary artery disease by as much as cholesterol increase of 20 mg /dl.
  • Homocysteine interacts with lysyl residues of collagen interfering with collagen cross linking.
  • It forms homocysteine thiolactone, a highly reactive free radical which thiolates LDL particles.
  • These particles tend to aggregate, are endocytosed by macrophages and increase the tendency for atherogenesis.
  • Providing adequate quantity of pyridoxine, vitamin B12 and folic acid will keep homocysteine in blood in normal levels.
  • Maternal hyperhomocysteinemia is known to increase the chances of neural tube defects in foetus. So, high doses of folic acid are advised in pregnancy.

Q. 6 The most important modifiable risk factor for atherosclerosis is:

 A

Hyperlipidemia

 B

Diabetes mellitus

 C

Cigarette Smoking

 D

Hypertension

Q. 6

The most important modifiable risk factor for atherosclerosis is:

 A

Hyperlipidemia

 B

Diabetes mellitus

 C

Cigarette Smoking

 D

Hypertension

Ans. C

Explanation:

Answer is C (Cigarette Smoking)
Cigarette smoking is the single most important modifiable risk factor for atherosclerosis.

  • Smoking is the single most important modifiable risk factor for the development of Peripheral Artery Disease (PAD)
  • Smoking cessation is the single most important target Pr coronary artery disease (CAD) Prevention
  • Hypertension continues to be the most important of all modifiable risk factors for stroke

Quiz In Between


Q. 7 Which of the following statements about Atherosclerosis is true:

 A

Intake of Unsaturated Fatty Acids is associated with decreased risk

 B

Extent of lesions in veins is similar as that in arteries

 C

Thoracic Aorta is more commonly involved than abdominal aorta

 D

Hypercholesterolemia alone does not increase the risk of atherosclerosis per se

Q. 7

Which of the following statements about Atherosclerosis is true:

 A

Intake of Unsaturated Fatty Acids is associated with decreased risk

 B

Extent of lesions in veins is similar as that in arteries

 C

Thoracic Aorta is more commonly involved than abdominal aorta

 D

Hypercholesterolemia alone does not increase the risk of atherosclerosis per se

Ans. A

Explanation:

Answer is A (Intake of Unsaturated Fatty Acids is associated with decreased risk)

The maximal benefit is observed with Omega 3 Poly-unsaturated Fatty Acids, however Mono-unsaturated Fatty Acids also have consistent anti-atherosclerotic benefits and both Poly-unsaturated Fatty Acids (PUFA) and Mono­unsaturated Fatty Acids (MUFA) are considered Cardioprotective Fatty Acids.

Hypercholestoremia alone may increase the risk of Atherosclerosis

`Hyperlipidemia and more specifically hypercholesterolemia is a major risk factor lb,. atherosclerosis. Even in the absence of other factors, hypercholesterolemia is sufficient to stimulate lesion development’. – Robbins 8th/497 Extent of Athrosclerosis is more severe in arteries than in veins

Atherosclerosis is always severe in areas where pressure and velocity are high (as in arteries) in contrast to areas where pressure and velocity are low (as in veins).

‘Overall atherosclerosis is more severe in high-pressure arteries than in pulmonary arteries with lower blood pressure. It is least severe in veins where pressure and velocity are lowest’ – ‘Pan – Vascular Medicine’ by Topol (2002)/90 Abdominal Aorta is more commonly involved than Thoracic Aorta

`Abdominal Aorta is more commonly involved than Thoracic Aorta. Within the abdominal aorta lesions tend to be more prominent around the ostia’ – `Med Essentials’ (Kaplan Publishing) 2007/249

`In the systemic circulation  severity is accentuated in the abdominal aorta and large arteries of the lower limb where pulse wave reflection and summation effect elevate the pulse and systolic pressures. The disease is more severe in large  rather than small vessels indicating the importance of mural tension and Reynolds number both of which are proportional to radius increasing the likelihood and severity of effects of blood flow disturbance at arterial forks, junctions and curvatures’.- ‘Pan Vascular Medicine’


Q. 8

True about atherosclerosis ‑

 A

Chronic inflammatory disorder of vessel wall

 B

Not lead to complications of vessel wall

 C

Thoracic aorta more than abdominal aorta

 D

Atherosclerostic plaques do not demonstrate neovascularization

Q. 8

True about atherosclerosis ‑

 A

Chronic inflammatory disorder of vessel wall

 B

Not lead to complications of vessel wall

 C

Thoracic aorta more than abdominal aorta

 D

Atherosclerostic plaques do not demonstrate neovascularization

Ans. A

Explanation:

Ans. is ‘a’ i.e., Chronic inflammatory disorder of vessel wall

Facts about atherosclerosis

Is a chronic inflammatory and healing response of the arterial wall to endothelial injury.

Atherosclerosis progresses in the following sequence:

Endothelial injury and dysfunction → Accumulation of lipoproteins (mainly LDL) Monocyte adhesion to the endothelium, followed by migration into the intima and transformation into macrophages and foam cells → Platelet adhesion factor release from activated platelets, macrophages, and vascular wall cells → Smooth muscle cell proliferation, extracellular matrix production, and recruitment of T cells → Lipid accumulation both extracellularly and within cells (macrophages and smooth muscle cell).

In descending order, the most extensively involved vessels are the lower abdominal aorta, the coronary arteries, the popliteal arteries, the internal carotid arteries, and the vessels of the circle of Willis. In humans, the abdominal aorta is typically involved to a much greater degree than the thoracic aorta.



Q. 9

Foam cells in atherosclerosis contain lipid in the form of ‑

 A

Oxidized LDL

 B

Reduced LDL

 C

Oxidized VLDL

 D

Reduced VLDI

Q. 9

Foam cells in atherosclerosis contain lipid in the form of ‑

 A

Oxidized LDL

 B

Reduced LDL

 C

Oxidized VLDL

 D

Reduced VLDI

Ans. A

Explanation:

Ans. is ‘a’ i.e., Oxidized LDL

Morphology of atherosclerotic plaque

There are three major components of an atherosclerotic plaques :-

i) Cells : Smooth muscle cell and macrophages are the major cells with some contribution from foam cells (lipid-laden macrophages), and lymphocytes. Advanced atherosclerotic plaque may lack smooth muscles as smooth muscle cells undergo apoptosis.

ii) Extracellular matrix : Collagen, elastic fibers, proteoglycans.

iii) Lipids : Both intracellular and extracellular, with cholesterol and cholesterol ester being the major lipids.

Quiz In Between


Q. 10 Following are the modifiable risk factors of atherosclerosis except ‑

 A

Physical inactivity

 B

Obesity

 C

Diabetes

 D

Hypertension

Q. 10

Following are the modifiable risk factors of atherosclerosis except ‑

 A

Physical inactivity

 B

Obesity

 C

Diabetes

 D

Hypertension

Ans. B

Explanation:

Ans. is ‘b’ i.e., Obesity


Q. 11

True about the basic structure of atherosclerosis plaque is ‑

 A

Concave part formed by fibrous cap

 B

Convex part formed by tunica media of the vessel

 C

Convex part formed by fibrous cap

 D

Necrotic core contains collagen, elastin and proteoglycans

Q. 11

True about the basic structure of atherosclerosis plaque is ‑

 A

Concave part formed by fibrous cap

 B

Convex part formed by tunica media of the vessel

 C

Convex part formed by fibrous cap

 D

Necrotic core contains collagen, elastin and proteoglycans

Ans. C

Explanation:

Ans. is ‘c’ i.e., Convex part formed by fibrous cap

  • The convex part is formed by the fibrous cap, which consists of smooth muscle cells, macrophages, foam cells, lymphocytes, collagen, elastin and proteoglycans.
  • The central necrotic core is formed of cell debris, cholesterol crystals, foam cells and calcium.
  • The concave part is formed by the tunica media of the vessel

Q. 12 Atherosclerosis initiation by fibroblast plaque is mediated by injury to ‑

 A

Smooth muscle

 B

Media

 C

Adventitia

 D

Endothelium

Q. 12

Atherosclerosis initiation by fibroblast plaque is mediated by injury to ‑

 A

Smooth muscle

 B

Media

 C

Adventitia

 D

Endothelium

Ans. D

Explanation:

Ans. is ‘d’ i.e., Endothelium

  • The most acceptable hypothesis for the pathogenesis of atherosclerosis is “the response to injury hypothesis”.
  • According to this hypothesis, atherosclerosis is a chronic inflammatory response of the arterial wall initiated by injury to endothelium.

Pathogenesis of atherosclerosis

  • Following stages occurs in the pathogenesis of Atherosclerosis:
  • Endothelial injury
  • Earliest stages of the development of atherosclerosis are mediated by the inflammatory cascade.
  • Inflammation mediated injury to endothelium is the cornestone in the development of atherosclerosis.
  • After injury, endothelium is activated and there is increased expression of adhesion molecule-VCAM-1 and
  • there is increased permeability to endothelium.
  • TNF is the major cytokine to induce this expression.

Migration of leukocytes

  • When VCAM-1 is expressed on endothelium, leukocytes adhere to the endothelium.
  • Leukocytes than cross the endothelial barrier and begin to accumulate in subendothelial intimal space.
  • Macrophages engulf LDL cholesterol and form foam cells → formation of earliest lesion, i.e. fatty streak.
  • Macrophages also form oxygen free radicals that cause oxidation of LDL to yield oxidized LDL (modified LDL).
  • Smooth muscle cell migration and proliferation
  • Inflammatory cells in subendothelial intimal space secrete cytokines, mainly PDGF, TGF-ct and FGF which cause migration of smooth muscle cells from media to subendothelial intimal space as well as their proliferation.

Maturation of plaque

  • Smooth muscle cells synthesize extracellular matrix (especially collegen) and convert a fatty streak into a mature fibrofatty atheroma, and contribute to the progressive growth of atherosclerotic lesions.

Q. 13 Identify this lesion in the formation of Atherosclerosis.

 A

Early lesion

 B

Fully developed Atheromatous Plaque

 C

Complicated Plaque

 D

None of the above.

Q. 13

Identify this lesion in the formation of Atherosclerosis.

 A

Early lesion

 B

Fully developed Atheromatous Plaque

 C

Complicated Plaque

 D

None of the above.

Ans. C

Explanation:

Ans:C.)Complicated Plaque
Schematic Evolution of Lesions in Atherosclerosis.
[img id=6454] 
MORPHOLOGIC FEATURES

1. FATTY STREAKS AND DOTS. 

  • Grossly, the lesions may appear as flat or slightly elevated and yellow.
  • They may be either in the form of small, multiple dots, about 1 mm in size, or in the form of elongated, beaded streaks.
  • Microscopically, fatty streaks lying under the endothelium are composed of closely-packed foam cells, lipid containing elongated smooth muscle cells and a few lymphoid cells. 

2. GELATINOUS LESIONS.

  • They are round or oval, circumscribed grey elevations, about 1 cm in diameter.
  • Microscopically, gelatinous lesions are foci of increased ground substance in the intima with thinned overlying endothelium.

3. ATHEROMATOUS PLAQUES.

  • A fully developed atherosclerotic lesion is called atheromatous plaque, also called fibrous plaque, fibrofatty plaque or atheroma.
  • Grossly, atheromatous plaques are white to yellowish white lesions, varying in diameter from 1-2 cm and raised on the surface by a few millimetres to a centimetre in thickness.
  • Cut section of the plaque reveals the luminal surface as a firm, white fibrous cap and a central core composed of yellow to yellow-white, soft, porridgelike material.
  • Microscopically, the following features are invariably present :
  • Superficial luminal part of the fibrous cap is covered by endothelium, and is composed of smooth muscle cells, dense connective tissue and extracellular matrix containing proteoglycans and collagen.
  • Cellular area under the fibrous cap is comprised by a mixture of macrophages, foam cells, lymphocytes and a few smooth muscle cells which may contain lipid.
  • Deeper central soft core consists of extracellular lipid material, cholesterol clefts, fibrin, necrotic debris and lipid laden foam cells.

4. COMPLICATED PLAQUES.

  • Various pathologic changes that occur in fully-developed atheromatous plaques are called the complicated lesions. 
  • These changes include calcification, ulceration, thrombosis, haemorrhage and aneurysmal dilatation.

Quiz In Between



Mitochondrial DNA

Mitochondrial DNA

Q. 1 Mitochondrial DNA is:

 A

Closed circular

 B

Nicked circular

 C

Linear

 D

Open circular

Q. 1

Mitochondrial DNA is:

 A

Closed circular

 B

Nicked circular

 C

Linear

 D

Open circular

Ans. A

Explanation:

Mitochondrial DNA is a closed circular double helix molecule which is transmitted maternally and is found within cells in multiple copies.
It contains 37 genes. All of these genes are essential.

Ref: Ganong’s Review of Medical Physiology, 22nd Edition, Page 10

 


Q. 2

All of the following states are TRUE regarding mitochondrial DNA (mtDNA) disease, EXCEPT:

 A

mtDNA contains only 37 genes

 B

Cause Leber hereditary optic neuropathy

 C

Mitochondrial genome is maternally transmitted

 D

Heteroplasmy is a feature of mtDNA

Q. 2

All of the following states are TRUE regarding mitochondrial DNA (mtDNA) disease, EXCEPT:

Cause Leber hereditary optic neuropathy

 A

mtDNA contains only 37 genes

 B
 C

Mitochondrial genome is maternally transmitted

 D

Heteroplasmy is a feature of mtDNA

Ans. D

Explanation:

All human cells contain two genomes: one in the nucleus and one in the mitochondria. 

  • The mitochondrial genome contains only 37 genes
  • Genome is maternally transmitted. 
The ratio of genetically aberrant to normal mitochondria transmitted can vary during mitosis and through generations—a situation known as heteroplasmy. People with entirely faulty mitochondria (homoplasmy) or a large proportion of faulty mitochondria may develop a mtDNA disease. 
 
These are clinically heterogeneous but usually severe diseases resulting from defects in energy production and include deafness, blindness, diabetes, loss of skills, and heart and liver failure. About 1 in 400 people has a maternally inherited mtDNA mutation.
 
Ref: Ethics of mitochondrial gene replacement: from bench to bedside, Annelien L Bredenoord ; BMJ 2010;341:c6021

Q. 3 True about mitochondrial DNA

 A

UGA codes for tryptophan

 B

Codes for 13 protein

 C

Circular double stranded DNA

 D

All

Q. 3

True about mitochondrial DNA

 A

UGA codes for tryptophan

 B

Codes for 13 protein

 C

Circular double stranded DNA

 D

All

Ans. D

Explanation:

A, B,C i.e. UGA codes for tryptophan, Codes for 13 protein, Circular double stranded DNA, Mitrochondrial disease occur due to Point Mutations and Large-Scale Rearrangements

Quiz In Between


Q. 4

Mitochondrial DNA is:

 A

Paternally inherited

 B

Maternally inherited

 C

Horizontal inheritance

 D

Vertical inheritance

Q. 4

Mitochondrial DNA is:

 A

Paternally inherited

 B

Maternally inherited

 C

Horizontal inheritance

 D

Vertical inheritance

Ans. B

Explanation:

B i.e. Maternally inherited


Q. 5

Mitochondrial DNA (mt- DN(A) is known for all except –

 A

Maternal inheritance

 B

Heteroplasmy

 C

Leber hereditary optic neuropathy is the prototype

 D

Nemaline myopathy results due to mutations in mt- DNA

Q. 5

Mitochondrial DNA (mt- DN(A) is known for all except –

 A

Maternal inheritance

 B

Heteroplasmy

 C

Leber hereditary optic neuropathy is the prototype

 D

Nemaline myopathy results due to mutations in mt- DNA

Ans. D

Explanation:

Ans. is ‘d’ i.e., Nemaline myopathy results due to mutations in mt- DNA

o Nemaline myopathy is not a mitochondria] disorder.

o Mitochondrial DNA is always maternally inherited.

o Heteroplasmy is the presence of mixture of more than one type of an organelle genome (mt- DNA) within a cell or individual. It is a factor for the severity of mitochondrial disease, since every eukaryotic cell contains many hundreds of copies of mt- DNA; it is possible and indeed very frequent for mutations to affect only some of the copies, while the remaining ones are unaffected.


Q. 6 Function of mitochondrial DNA ‑

 A

Encodes proteins of cell membrane

 B

Encodes proteins of respiratory chain

 C

Helps in cell replication

 D

Formation of rRNA

Q. 6

Function of mitochondrial DNA ‑

 A

Encodes proteins of cell membrane

 B

Encodes proteins of respiratory chain

 C

Helps in cell replication

 D

Formation of rRNA

Ans. B

Explanation:

 
Human mitochondria contain two to ten copies of a small circular double-stranded DNA molecule that makes up approximately 1% of total cellular DNA.
The majority of the peptides in mitochondria (about 54 out of 67) are coded by nuclear genes.
The rest are coded by genes found in mitochondrial (mt) DNA
This mtDNA codes for mt ribosomal and transfer RNAs and for 13 proteins that play key roles in the respiratory chain.

Quiz In Between



External Ear- Pinna / Auricle

Pinna / Auricle

Q. 1

Ear pinna develops from ____________

 A

Ectoderm

 B Endoderm

 C

Mesoderm

 D

All 

Q. 1

Ear pinna develops from ____________

 A

Ectoderm

 B

Endoderm

 C

Mesoderm

 D

All 

Ans. A

Explanation:

 Ans:A.)Ectoderm

  • First branchial cleft is the precursor of external auditory canal.
  • Around the sixth week of embryonic life, a series of six tubercles appear around the first branchial cleft
  • Branchial clefts are ectodermal in origin.

Q. 2

The cartilage present in Ear Pinna is:

 A Hyaline 

 B

Elastic

 C

Fibrocartilage

 D

None

Q. 2

The cartilage present in Ear Pinna is:

 A

Hyaline 

 B

Elastic

 C

Fibrocartilage

 D

None

Ans. B

Explanation:

Elastic Cartilage 


Q. 3

Which of the following is formed at birth?

 A

Mastoid process

 B

Pinna

 C

Otic capsule

 D

Secondary areola

Q. 3

Which of the following is formed at birth?

 A

Mastoid process

 B

Pinna

 C

Otic capsule

 D

Secondary areola

Ans. B

Explanation:

Quiz In Between


Q. 4

The presence of white fibrocartilage is a feature of all of the following, EXCEPT:

 A

Acetabular labrum

 B

Intervertebral disc

 C

Meniscus

 D

Pinna

Q. 4

The presence of white fibrocartilage is a feature of all of the following, EXCEPT:

 A

Acetabular labrum

 B

Intervertebral disc

 C

Meniscus

 D

Pinna

Ans. D

Explanation:

Pinna is composed of a thin plate of yellow elastic cartilage, covered with integument
It is connected to the surrounding parts by ligaments and muscles; and to the commencement of the external acoustic meatus by fibrous tissue.


Q. 5

All are types of elastic cartilages, EXCEPT:

 A

Pinna

 B

Epiglottis

 C

Tip of arytenoid

 D

Thyroid cartilage

Q. 5

All are types of elastic cartilages, EXCEPT:

 A

Pinna

 B

Epiglottis

 C

Tip of arytenoid

 D

Thyroid cartilage

Ans. D

Explanation:

Cartilage is a fom of connective tissue, which contains a gel like matrix embedded with cells. They are of three types: Hyaline cartilage, elsatic cartilage and fibrous cartilage.
Elastic cartilage consists of numerous yellow elastic fibres embedded in a matrix which explains its flexibility. It is seen in auricle of the ear, external auditory meatus, auditory tube and the epiglottis.

Larynx is composed of several cartilages. The thyroid cartilage, cricoid cartilage, arytenoid cartilages, corniculate cartilages and cuneiform cartilages are all composed of hyaline cartilage.

Ref: Snell’s, Clinicql Anatomy, 7th Edition, Page 39


Q. 6

Fibrocartilage is present in all, EXCEPT:

 A

Pinna

 B

Symphysis pubis

 C

Intervertebral disc

 D

Menisci of knee joint

Q. 6

Fibrocartilage is present in all, EXCEPT:

 A

Pinna

 B

Symphysis pubis

 C

Intervertebral disc

 D

Menisci of knee joint

Ans. A

Explanation:

Fibrocartilage is a white opaque structure due to dense collage fibres (type I and II).
When a fibrous tissue is subjected to pressure it is replaced by fibrocartilage.
It is seen in joints, symphysis, intervertebral discs, menisci and labra (shoulder joint and hip joint).
Pinna is a type of elastic cartilage. Elastic cartilages are seen at sites concerned with production or reception of sounds eg external acoustic meatus (lateral part), auditory tube and epiglottis.

Quiz In Between


Q. 7

Sensory nerve supply of pinna is :

 A

Mandibular nerve

 B

Maxillary nerve

 C

Facial nerve

 D

Abducent nerve

Q. 7

Sensory nerve supply of pinna is :

 A

Mandibular nerve

 B

Maxillary nerve

 C

Facial nerve

 D

Abducent nerve

Ans. A

Explanation:

Auriculotemporal nerve, a branch of mandibular nerve (V3)(2 supplies the external acoustic meatus, external surface of auricle above this, skin of temporal region and TM joint.


Q. 8

Major part of the skin of pinna is supplied by:

 A

Aurculo temporal nerve

 B

Auricular branch of the vagus

 C

Posterior auricular nerve

 D

Great auricular nerve

Q. 8

Major part of the skin of pinna is supplied by:

 A

Aurculo temporal nerve

 B

Auricular branch of the vagus

 C

Posterior auricular nerve

 D

Great auricular nerve

Ans. D

Explanation:

D i.e. Great auricular


Q. 9

All of the following nerves supply auricle and extrernal meatus except:

 A

Trigeminal nerve

 B

Glossopharyngeal nerve

 C

Facial nerve

 D

Vagus nerve

Q. 9

All of the following nerves supply auricle and extrernal meatus except:

 A

Trigeminal nerve

 B

Glossopharyngeal nerve

 C

Facial nerve

 D

Vagus nerve

Ans. B

Explanation:

Quiz In Between


Q. 10

Which of the following nerves has no sensory supply to the auricle?

 A

Lesser occipital nerve

 B

Greater auricular nerve

 C

Auricular branch of vagus nerve

 D

Tympanic branch of glossopharyngeal nerve

Q. 10

Which of the following nerves has no sensory supply to the auricle?

 A

Lesser occipital nerve

 B

Greater auricular nerve

 C

Auricular branch of vagus nerve

 D

Tympanic branch of glossopharyngeal nerve

Ans. D

Explanation:

Q. 11

Skin over pinna is fixed:

 A

Firmly on both sides

 B

Loosely on medial side

 C

Loosely on lateral side

 D

Loosely on both side

Q. 11

Skin over pinna is fixed:

 A

Firmly on both sides

 B

Loosely on medial side

 C

Loosely on lateral side

 D

Loosely on both side

Ans. B

Explanation:

Skin over the pinna is closely adherent to the perichondrium on the lateral surface while it is loosely attached on the medial surface.


Q. 12

Major part of the skin of pinna is supplied by:

 A

Auriculotemporal nerve

 B

Auricular branch of vagus

 C

Lesser occipital nerve

 D

Greater auricular nerve

Q. 12

Major part of the skin of pinna is supplied by:

 A

Auriculotemporal nerve

 B

Auricular branch of vagus

 C

Lesser occipital nerve

 D

Greater auricular nerve

Ans. D

Explanation:

Ans. is d i.e. greater auricular nerve

Quiz In Between


Q. 13

Auricle of the ear is made of:       

 A

Hyaline cartilage

 B

Fibrocartilage

 C

Elastic cartilage

 D

None of the above

Q. 13

Auricle of the ear is made of:       

 A

Hyaline cartilage

 B

Fibrocartilage

 C

Elastic cartilage

 D

None of the above

Ans. C

Explanation:

 
There are three types of cartilage:

  • Hyaline cartilage has a high proportion of amorphous matrix. Throughout childhood and adolescence, it plays an important part in the growth in length of long bones (epiphyseal plates are composed of hyaline cartilage). It has a great resistance to wear and covers the articular surfaces of nearly all synovial joints.
  • Fibrocartilage has many collagen fibers embedded in a small amount of matrix and is found in the discs within joints (e.g., the temporomandibular joint, sternoclavicular joint, and knee joint) and on the articular surfaces of the clavicle and mandible. Fibrocartilage, if damaged, repairs itself slowly in a manner similar to fibrous tissue elsewhere.
  • Elastic cartilage possesses large numbers of elastic fibers embedded in matrix. It is flexible and is found in the auricle of the ear, the external auditory meatus, the auditory tube, and the epiglottis. Elastic cartilage, if damaged, repairs itself with fibrous tissue.

Q. 14 Cauliflower ear seen in:

 A

Hematoma of the auricle

 B

Carcinoma of the auricle

 C

Fungal infection of the auricle

 D

Congenital deformity

Q. 14

Cauliflower ear seen in:

 A

Hematoma of the auricle

 B

Carcinoma of the auricle

 C

Fungal infection of the auricle

 D

Congenital deformity

Ans. A

Explanation:

Cauliflower ear (boxer’s ear, wrestler’s ear) is an acquired deformity of the outer ear.

In this injury, the ear can shrivel up and fold in on itself and appear pale, giving it a cauliflower-like appearance, hence the term cauliflower ear.

Wrestlers, boxers and martial artists in particular are susceptible to this type of injury. When the ear is struck and a blood clot develops under the skin, or the skin is sheared from the cartilage, the connection of the skin to the cartilage is disrupted.


Q. 15 A 12 year old presents with fever, unilateral post auricular pain, mastoid bulging displacing the pinna forward and outwards with loss of bony trabeculae. This patient has history of chronic persistent pus discharge from same ear. Treatment of choice is‑

 A

Antibiotics only

 B

Incision and drainage

 C

Antibiotics, incision and drainage

 D

Mastoidectomy with incision, drainage and antibiotics

Q. 15

A 12 year old presents with fever, unilateral post auricular pain, mastoid bulging displacing the pinna forward and outwards with loss of bony trabeculae. This patient has history of chronic persistent pus discharge from same ear. Treatment of choice is‑

 A

Antibiotics only

 B

Incision and drainage

 C

Antibiotics, incision and drainage

 D

Mastoidectomy with incision, drainage and antibiotics

Ans. D

Explanation:

Ans: D. Mastoidectomy with incision, drainage and antibiotics 

The patient is presenting with features of postauricular subperiosteal abscess. Treatment for this is antibiotics along with drainage of abscess and cortical mastoidectomy.

This patient has developed this abscess as a complication of CSOM (History of chronic ear discharge) for which he requires meastoidectomy.

Quiz In Between



Von Recklinghausen’s Disneurofibromatosisease

(VON RECKLINGHAUSEN’S DISNEUROFIBROMATOSISEASE)

Q. 1

All are seen in neurofibromatosis EXCEPT?

 A Meningioma
 B

Lisch nodule

 C Axillary freckling
 D

Shagreen patch

Q. 1

All are seen in neurofibromatosis EXCEPT?

 A Meningioma
 B

Lisch nodule

 C Axillary freckling
 D

Shagreen patch

Ans. D

Explanation:

Shagreen patch REF: Harrison’s 17th ed chapter 374

“Shagreen patch is seen in tuberous sclerosis”

Feature

NF1

NF2

Mutation

NFl gene on chromosome 17 causes

NF2 gene on chromosome 22q.

 

von Recklinghausen’s disease. The NFl

NF2 encodes a protein called

 

gene is a tumor-suppressor gene; it

encodes a protein, neurofibromin

neurofibromin 2, schwannomin,

or merlin

Cutaneous feat              

cutaneous neurofibromas, pigmented

lesions of the skin called café au lait

spots, freckling in non-sun-exposed

areas such as the axilla, hamartomas

of the iris termed Lisch nodules, and

pseudoarthrosis of the tibia                      

Multiple café au lait spots and

peripheral neurofibromas occur

rarely                                                   

Complications

Aqueductal stenosis with

hydrocephalus, scoliosis, short stature,

hypertension, epilepsy, and mental

retardation may also occur.

A characteristic type of cataract,

juvenile posterior subcapsular

lenticular opacity, occurs in NF2

Neurological features

Patients with NF1 are at increased
risk of developing nervous
system neoplasms, including plexiform
neurofibromas, optic pathway gliomas
ependymomas, meningiomas
astrocytomas, and
pheochromocytomas. Neurofibromas
may undergo secondary malignant
degeneration and become

sarcomatous.

 
NF2 is characterized by the
development of bilateral vestibular
schwannomas in >90% of
individuals who inherit the gene
Patients with NF2 also have a
predisposition for the development
of meningiomas, gliomas, and
schwannomas of cranial and spinal

nerves


Q. 2

Neurofibromatosis true all, except ‑

 A

Autosomal recessive

 B

Associated with cataract

 C

Scoliosis

 D

Multiple fibroma

Q. 2

Neurofibromatosis true all, except ‑

 A

Autosomal recessive

 B

Associated with cataract

 C

Scoliosis

 D

Multiple fibroma

Ans. A

Explanation:

Autosomal recessive [Ref: Robbin’s 7thle p. 1413]

  • Neurofibromatosis is an inherited disorder
  • It is of two types: ?
  • Neurofibromatosis

– Neurofibromatois II

Genetics of Neurofibromatosis

  • Both the neurofibromas are inherited in an autosomal dominant pattern.
  • The genes for them are located on different chromosome 

         – NF-1—) Neurofibrin gene on chromosome 17
         – NF-2 —) Merlin gene on chromosome 22

NEUROFIBROMATOSIS TYPE I ?

  • Neurofibromatosis is a comparatively common hereditary disorder in which the skin, nevous system, bone, endocrine glands and sometimes other organs are at the sites of a variety of congenital abnormalities often taking the fonn of benign tumours.

. The main feature of neurofibromatosis I is –

(i) Spots of hyperpigmentation

and

(ii)    Cutaneous and subcutaneous neurofibromatous tumours’.

Hyperpigmentation in Neurofibromatosis I takes two forms 😕

a) Cafe – au – lait spots’

.   These are patches of pigmentation and they appear shortly after birth’ and occur anywhere on the body.

.   They are light brown in colour (cafe – au – lait) and do not change in number as the patient ages but they increase in size during puberty.

.   Presence of more than six cafe – au – lait spots > 1.5 cm in size is considered diagnostic of Neurofibromatosis.

b) Freckles’

.   Neurofibromatosis I is also characterized by the presence of Freckles like or diffuse pigmentation of the axillae and other intertriginous areas (groin, under breast) and small round whitish spots. When coupled with cafe au lait patches they are virtually pathogtzomonice of the disease.

ii) Neurofibromas

a) Cutaneous tumours

.   They are situated in the dermis and form discrete soft or, firm papules.

.   They are ,flesh coloured or violaceous and often topped with comedo. When pressed, the soft tumours tend to invaginate through a small opening in the skin giving the feeling of a seedless raisin or a scrotum without a testicle. This phenomenon is spoken of as “button holding”.

b) Subcutaneous tumours

.   They take two forms ?

a)   Firm discrete nodules attached to a nerve.

b) Plexiform neuromase (overgrowth of subcutaneous tissue sometimes reaching enormous size and occur most often in the face, scalp, neck and chest and may cause hideous disfigurement).

Lisch Nodule’?

  • This is another unique .finding of neurofibromatosiso.

.   It is a small whitish spote present in the iris.

Tumours associated with Neurofibromatosis I are

1) Tumours of the CNS

a)  Optic Nerve Gliomao

b)  Non-optic Gliomas (usually low grade astrocytomas)

c)   Nonneoplastic ‘ hamartomatous” lesion

Osborn writes –

“The common CNS tumor in NF-1 is optic nerve glioma occuring in 5 to 15% of casese”

2) Other tumours associated with NF-1

a)  Pheochromocytoma

b)  Rhabdomyosarcoma

c)   leukemia (myeloid leukemia)

d)     Wilms tumour

e) Juvenile Xanthogranuloma


Q. 3

Neurofibromatosis I is most commonly associated with

 A

Brain stern gliomas

 B

Optic pathway glioma

 C

Sub ependymal pilocytic astrocytoma

 D

Glioblastoma multifonne

Q. 3

Neurofibromatosis I is most commonly associated with

 A

Brain stern gliomas

 B

Optic pathway glioma

 C

Sub ependymal pilocytic astrocytoma

 D

Glioblastoma multifonne

Ans. B

Explanation:

Optic pathway Glioma [Ref Diagnostic Neuroadiology; Anne G.Osborn, 1994]

Tumours associated with Neurofibromatosis I are

1) Tumours of the CNS

a) Optic Nerve Gliomao

b) Non-optic Gliomas (usually low grade astrocytomas)

c) Nonneoplastic ” hamartomatous” lesion

Osborn writes ?

“The common CNS tumor in NF-1 is optic nerve glioma occuring in 5 to 15% of cases’)”

2) Other tumours associated with NF-1

a) Pheochromocytoma

b) Rhabdomyosarcoma

c)  leukemia (myeloid leukemia)

d)  Wilms tumour

e)  Juvenile Xanthogranuloma

Quiz In Between


Q. 4 A 22-year-old patient, Sreeraj presents with multiple neural tumors, pigmented iris hamartomas, and numerous tan macules on his skin. He informs the physician that his father, as well as one uncle and his paternal grandfather, had a similar condition. This patient likely suffers from which of the following?

 A

Ependymoma

 B

Huntington disease

 C

Marfan syndrome

 D

Neurofibromatosis type I

Q. 4

A 22-year-old patient, Sreeraj presents with multiple neural tumors, pigmented iris hamartomas, and numerous tan macules on his skin. He informs the physician that his father, as well as one uncle and his paternal grandfather, had a similar condition. This patient likely suffers from which of the following?

 A

Ependymoma

 B

Huntington disease

 C

Marfan syndrome

 D

Neurofibromatosis type I

Ans. D

Explanation:

Neurofibromatosis type 1, or von Recklinghausen disease, is an autosomal dominant disorder with high penetrance, but variable expressivity. The disease has three major features:
(1) multiple neural tumors anywhere on or in the body
(2) numerous pigmented cutaneous lesions (café au lait spots); and
(3) pigmented iris hamartomas (Lisch nodules).

Electron micrographic studies show that the tumors are the result of the proliferation of fibroblasts or Schwann cells in the peripheral nerves, possibly due to ras inactivation.
There is no treatment, except for surgical resection of symptomatic tumors.

Ependymoma  can occur wherever ependymal cells are found. They are more common in children, and most often originate in the fourth ventricle. They are the most common intramedullary glioma of the spinal cord.
 
Huntington disease, an autosomal dominant disorder, is characterized by severe degeneration of the caudate nucleus along with degenerative changes in the putamen and cortex.
In addition to chorea, these patients frequently suffer from athetoid movements, progressive dementia, and behavioral disorders.
 
Marfan syndrome  is due to a defect in the gene for fibrillin.
The major clinical findings involve the skeleton, cardiovascular system, and the eye.
Affected individuals tend to be tall with long extremities and long, tapering appendages.
Mitral valve prolapse and dilatation of the aortic valve ring or aortic dissection due to cystic medial degeneration are common.

Q. 5 Ependymomas are commonly associated with:

 A

Tuberous sclerosis

 B

Neurofibromatosis 1

 C

Neurofibromatosis 2

 D

All of the above

Q. 5

Ependymomas are commonly associated with:

 A

Tuberous sclerosis

 B

Neurofibromatosis 1

 C

Neurofibromatosis 2

 D

All of the above

Ans. C

Explanation:

Ependymomas most often arise next to the ependyma-lined ventricular system, including the oft-obliterated central canal of the spinal cord. In the first two decades of life they typically occur near the fourth ventricle and constitute 5% to 10% of the primary brain tumors in this age group. In adults the spinal cord is the most common location; tumors in this site are particularly frequent in the setting of neurofibromatosis type 2
            
Ref: Robbins 8th edition Chapter 28.

Q. 6

Which of the following is the most common tumour associated with Neurofibromatosis -1 (NF-I) in a child?

 A

Juveile Myelomonocytic Leukemia (JMML)

 B

Acute Lymphoblastic Leukemia (ALL)

 C

Acute Myeloid Leukemia (AML)

 D

Chronic Myeloid Leukemia (CML)

Q. 6

Which of the following is the most common tumour associated with Neurofibromatosis -1 (NF-I) in a child?

 A

Juveile Myelomonocytic Leukemia (JMML)

 B

Acute Lymphoblastic Leukemia (ALL)

 C

Acute Myeloid Leukemia (AML)

 D

Chronic Myeloid Leukemia (CML)

Ans. A

Explanation:

Children with neurofibromatosis type 1 have higher risk of developing juvenile myelomonocytic leukemia.
Ref: Essential pediatrics by O.P.Ghai 6th edn/page 545; Rook’s textbook of dermatology, Volume 1 By Arthur Rook, Tony Burns (FRCP.)page 2-32.

Quiz In Between


Q. 7

Pseudarthrosis may be seen in all of the following conditions, EXCEPT:

 A

Fracture

 B

Idiopathic

 C

Neurofibromatosis

 D

Osteomyelitis

Q. 7

Pseudarthrosis may be seen in all of the following conditions, EXCEPT:

 A

Fracture

 B

Idiopathic

 C

Neurofibromatosis

 D

Osteomyelitis

Ans. D

Explanation:

Causes of Pseudarthrosis (In decreasing order of frequency) are:

  • Neurofibromatosis (50% patients of pseudarthrosis have NF)
  • Nonunion of fracture (including pathological fracture)
  • Congenital (mostly in lower to middle third of tibia with cupping of proximal bone end and pointing of distal bone end)
  • Idiopathic
  • Osteogenesis imperfecta
  • Fibrous dysplasia
  • Cleidocranial dysplasia
  • Ankylosing spondylitis (in fused bamboo spine)
  • Post surgical e.g. triple arthrodesis, spinal fusion etc. as a complication. 
Ref: Robbin’s Pathologic basis of Disease 7/e, Page 1289; Apley’s system of Orthopedics & fractures 8/e, Page 156,164,544 ; Natarajan’s orthopedics , Page 27; Murcer’s Orthopedic surgery 9/e, Page 433, 811, 1095, 672,736.

Q. 8 Which of the following is the MOST common skeletal manifestation in Type-1 Neurofibromatosis?

 A

Cortical thinning of long bones

 B

Pseudoarthrosis

 C

Sphenoid dysplasia

 D

Scoliosis

Q. 8

Which of the following is the MOST common skeletal manifestation in Type-1 Neurofibromatosis?

 A

Cortical thinning of long bones

 B

Pseudoarthrosis

 C

Sphenoid dysplasia

 D

Scoliosis

Ans. D

Explanation:

Von Recklinghausen’s Disease or NF-1 – skeletal manifestations
 
Scoliosis is the most common skeletal manifestation of NF-1, affecting 10%–30% of patients.
 
More Info: There are two other bony lesions distinctive enough to be included in the diagnostic criteria for NF-1. 
 
1. Dysplasia of the wing of the sphenoid bone, results in poor formation of the wall and/or floor of the orbit. This leads to proptosis (from herniation of meninges or brain into the orbit) or enophthalmos.
 
2. Dysplasia of a long bone, characterized by congenital thinning and bowing, affects approximately 2% of children with NF-1.
Although the tibia is most commonly affected, the femur, humerus and other long bones may also be involved.
Failure of primary union following a fracture results in a “false joint” or pseudarthrosis.
 
Ref: Listernick R., Charrow J. (2012). Chapter 141. The Neurofibromatoses. In L.A. Goldsmith, S.I. Katz, B.A. Gilchrest, A.S. Paller, D.J. Leffell, N.A. Dallas (Eds), Fitzpatrick’s Dermatology in General Medicine, 8e.

Q. 9

All of the following statements about Neurofibromatosis are true, except?

 A

Cataract

 B

Scoliosis

 C

Cutaneous neurofibromas

 D

Autosomal Recessive Inheritance

Q. 9

All of the following statements about Neurofibromatosis are true, except?

 A

Cataract

 B

Scoliosis

 C

Cutaneous neurofibromas

 D

Autosomal Recessive Inheritance

Ans. D

Explanation:

Neurofibromatoses are a group of clinically and genetically different autosomal dominant hereditary diseases that predispose to benign and malignant tumors of the nervous system. It is of two types NF 1 and NF2.
Cutaneous neurofibromas occur in NF1, and NF 2 is associated with posterior subcapsular cataract.

Ref: Harrison’s Internal Medicine, 18th Edition, Chapter 379; Color Atlas of Genetics By Eberhard Passarge, 3rd Edition, Page 338

Quiz In Between


Q. 10

All of the neurocutaneous signs are seen in Neurofibromatosis Type 2, EXCEPT:

 A

Meningioma

 B

Lisch nodule

 C

Axillary freckling

 D

Shagreen patch

Q. 10

All of the neurocutaneous signs are seen in Neurofibromatosis Type 2, EXCEPT:

 A

Meningioma

 B

Lisch nodule

 C

Axillary freckling

 D

Shagreen patch

Ans. D

Explanation:

Shagreen patch is highly characteristic of tuberous sclerosis and is seen in 80% of patients. It occurs in early childhood and may be the first sign of disease. They are soft, flesh colored to yellow plaques with an irregular surface. It is most commonly seen in the lumbosacral region. 

Features of Neurofibromatosis 1 are: cafe au lait spots, neurofibromas or plexiform neuroma, freckling, optic glioma and Lisch nodules.

Features of Neurofibromatosis 2 are: bilateral vestibular schwannomas, multiple meningioma, spinal ependymoma, astrocytoma, posterior subcapsular lens opacities and retinal hamartomas.


Q. 11

Which of the following is associated with bilateral eighth nerve neuromas?

 A

Neurofibromatosis I

 B

Neurofibromatosis II

 C

Tuberous sclerosis

 D

All of the above

Q. 11

Which of the following is associated with bilateral eighth nerve neuromas?

 A

Neurofibromatosis I

 B

Neurofibromatosis II

 C

Tuberous sclerosis

 D

All of the above

Ans. B

Explanation:

Neurofibromatosis Type II is characterized by bilateral tumors of the eighth cranial nerve (the vestibulocochlear nerve) and any of the following: meningiomas, schwannomas, gliomas, or juvenile subcapsular cataracts.


Q. 12

Which one of the following is the most common tumor associated with type I neurofibromatosis

 A

Optic nerve glioma

 B

Meningioma

 C

Acoustic schwannoma

 D

Low grade astrocytoma

Q. 12

Which one of the following is the most common tumor associated with type I neurofibromatosis

 A

Optic nerve glioma

 B

Meningioma

 C

Acoustic schwannoma

 D

Low grade astrocytoma

Ans. A

Explanation:

Ans. is ‘a’ i.e., Optic nerve glioma

Neurofibromatosis type I (Von-Recklinghewsen diseasel

o NF- 1 is diagnosed when any two of the following seven signs are present.

1. Six or more cafe-au-lait macules

o > 5 mm in prepupertal individuals

o > 15 mm in postpubertal individuals

  • Cafe-au-lait spots are the hallmark of neurofibromatosis and are present in almost 100% of the patient.
  1. Axillary or inguinal freckling
  2. Two or more Lisch nodules.
  • Lisch nodules are hamartomas located within the iris.
  1. Two or more neurofibroma or one plexiform neurofibroma.

o Typically involve the skin, but may be situated along peripheral nerves and blood vessels. o They are small, rubbery lesions with a slight purplish discoloration of the overlying skin.

  1. A distinctive osseous lesion.
  • Sphenoid dysplasia or cortical thinning of long bones.
  1. Optic glioma
  2. A first degree relative with NF-1

o Other findings are : ‑

o Pseudoarthrosis of tibia.

  • Scoliosis is the most common orthopaedic problem in NF-1, but is not specific enough to be included as a diagnostic criterian.
  • Short stature

o Mental retardation, epilepsy

o Hypertension

o Aqueductal stenosis with hydrocephalus

o Meningiomas, ependynomas, Astrocytomas, pheochromocytomas.

o NF-1 is caused by mutation in NF-1 gene on chromosome 17 which encodes protein neurofibromin-1. Neurofibromatosis type -2

o NF-2 may be diagnosed when one of the following two features are present.

  1. Bilateral ocoustic neuroma Most distinctive feature
  2. A parent, sibling or child with NF-2 and either unilateral eighth nerve masses or any two of the following —> Neurofibroma, meningioma, glioma, Schwannoma or juvenile post subcapsular cataract.

o NF-2 is cause by mutation in NF-2 gene on chromosome 22 that encodes for protein neurofibromin 2, Schwannomin or merlin.

Quiz In Between


Q. 13 Neurofibromatosis true all, except-

 A

Autosomal recessive

 B

Associated with cataract

 C

Scoliosis

 D

Multiple fibroma

Q. 13

Neurofibromatosis true all, except-

 A

Autosomal recessive

 B

Associated with cataract

 C

Scoliosis

 D

Multiple fibroma

Ans. A

Explanation:

Ans. is ‘a’ i.e., Autosomal recessive

o Neurofibromatosis comprises of two distinct disorders –

  • Neurofibromatosis I

 Neurofibromatosis II

o The genes for these are located on different chromosomes.

o Both are inherited in an autosomal dominant pattern.

o The classical form of the disease with multiple neuromas is called Neurofibromatosis I and is caused by a mutation of the gene neurofibromin on chromosome 17


Q. 14

Which one of the following is the most common tumor associated with type I neurofibromatosis

 A

Optic nerve glioma

 B

Meningioma

 C

Acoustic schwannoma

 D

Low grade astrocytoma

Q. 14

Which one of the following is the most common tumor associated with type I neurofibromatosis

 A

Optic nerve glioma

 B

Meningioma

 C

Acoustic schwannoma

 D

Low grade astrocytoma

Ans. A

Explanation:

Ans. is ‘a’ i.e., Optic nerve glioma

Neurofibromatosis type I (Von-Recklinghewsen disease)

o NF-1 is diagnosed when any two of the following seven signs are present.

1. Six or more cafe-au-lait macules

             > 5 mm in prepupertal individuals

             > 15 mm in postpubertal individuals

               Cafe-au-fait spots are the hallmark of neurofibromatosis and are present in almost 100% of the patient.

2. Axillary or inguinal freckling
3. Two or more Lisch nodules.

             Lisch nodules are hamartomas located within the iris.

4. Two or more neurofibroma or one plexiform neurofibroma.

             Typically involve the skin, but may be situated along peripheral nerves and blood vessels.

             They are small, rubbery lesions with a slight purplish discoloration of the overlying skin.

5. A distinctive osseous lesion.

             Sphenoid dysplasia or cortical thinning of long bones.

6. Optic glioma
7. A first degree relative with NF-1

Other findings are : –

             Pseudoarthrosis of tibia.

             Scoliosis is the most common orthopaedic problem in NF-1, but is not specific enough to be included as a diagnostic criterian.

             Short stature


Q. 15 Wide neuralforamina is associated with:

 A

Neurofibromatosis type 1

 B

Sturge-Weber syndrome

 C

Von Hipple Lindau disease

 D

Tuberous sclerosis

Q. 15

Wide neuralforamina is associated with:

 A

Neurofibromatosis type 1

 B

Sturge-Weber syndrome

 C

Von Hipple Lindau disease

 D

Tuberous sclerosis

Ans. A

Explanation:

A i.e. Neurofibromatosis

Neurofibromatosis type 1 is associated with widening (enlargement) of neural foraminaQ (mostly secondary to dumbbell neurofibroma along exiting spinal nerve root or less commonly d/t dural ectasia, arachnoid cyst or lateral menngocele)Q, scalloping of posterior vertebral bodies, enlargement of internal auditory canal (d/t dural dysplasia), enlargement of optic foramen (d/t optic glioma), enlargement of orbital margins & superior orbital fissure (d/t plexiform neurofibroma) and sclerosis of optic foramen (d/t optic nerve sheath meningioma).

NF1 causes empty orbitQ, Herlequin appearance of orbit and herniation of middle cranial fossa structures into orbit d/t sphenoid bone hypoplasia.

Both neurofibromas (common in NF1) and Schwannomas (common in NF2) are benign nerve sheath tumors mostly found in intradural extramedullary location. Both are derived from Schwann cells, however, neurofibromas also have colagen & fibroblasts. Vestibular or acoustic Schwannoma (or neurilemmoma or acoustic neuroma of 8th cranial nerve) seen in NF2 1/t internal auditory canal (IAC) enlargement (erosion d/t mass centered on long axis of IAC forming acute angles with dural surface of petrous bone) and widening or obliteration of ipsilateral cerebello pontine angle cistern.

NF-2 is located on chromosome 22 and NF1 on chromosome 17(Mn 1 for 1 & 2 for 2). NF2 have propensity for developing MEN/MES i.e. meningioma, ependymoma (gliomas) and Schwannoma (neuromas). Nerves without Schwann cells are olfactory and optic nerve.

Schwannomas neurofibromas, on CT, appear as sharply marginated, unilateral, spherical, or lobular posterior mediastinal mass, with pressure erosion of adjacent rib or vertebral bodies or enlargment of neural foramen with occasional punctate intralesional calcifcation. Owing to their high lipid content, interstitial fluid and areas of cystic degeneration – Schwannomas are often of lower attenuation than skeleton muscle. Neurofibromas are often more homogenous & of higher attenuation than schwannomas (owing to fewer of above histological features). These may heterogenously enhance on contrast administration. On MRI both show variable intensity on T1WI but typically have similar signal intensity to the spinal cord. On T2WI these characteristically have high signal intensity peripherally and low signal intensity centrally (target sign) owing to collagen deposition. Both schwannoma & neurofibroma enhance on gadolinium administration.

Quiz In Between


Q. 16

Rib notching is found in :

 A

Neurofibromatosis

 B

Lymphangiomyomatosis

 C

Aortic aneurysm

 D

a and c

Q. 16

Rib notching is found in :

 A

Neurofibromatosis

 B

Lymphangiomyomatosis

 C

Aortic aneurysm

 D

a and c

Ans. D

Explanation:

A i.e. Neurofibromatosis; C i.e. Aortic aneurysm


Q. 17

Neurofibromatosis all are true except

 A

Autosomal recessive

 B

Scoliosis

 C

Neurofibroma

 D

Association with cataract

Q. 17

Neurofibromatosis all are true except

 A

Autosomal recessive

 B

Scoliosis

 C

Neurofibroma

 D

Association with cataract

Ans. A

Explanation:

A i.e. Autosomal recessive


Q. 18

The pathognomonic sign of neurofibromatosis is

 A

Cafe-au-lait macules

 B

Axillary frekling

 C

Shagreen patch

 D

None of the above

Q. 18

The pathognomonic sign of neurofibromatosis is

 A

Cafe-au-lait macules

 B

Axillary frekling

 C

Shagreen patch

 D

None of the above

Ans. B

Explanation:

B i.e. Axillary freckling

Neurofibromatosis is autosomal dominantQ disorder. Axillary freckling (crowe sign) is a pathognomic sign of von- Reckling hausen’s type 1 neurofibromatosisQ. Café – au – lait macules alone are not absolutely diagnostic of NF1, regardless of their size and number.

Quiz In Between


Q. 19 Neurofibromatosis is associated with –

 A

Papillary Ca

 B

Islet cell tumour

 C

Pheochromytoma

 D

Glucagonoma

Q. 19

Neurofibromatosis is associated with –

 A

Papillary Ca

 B

Islet cell tumour

 C

Pheochromytoma

 D

Glucagonoma

Ans. C

Explanation:

Ans. is ‘c’ i.e. Pheochromocytoma 

Following neoplasms are associated with Neurofibromatosis

Type I (Von Recklinghausen ds.)

Type II

Neurofibromas (including plexiform neurofibromas)

Bilateral vesibular schwannomas

 

Pheochromocytoma

 

Schwannoma of other cranial and spinal nerves

 

Optic gliomas

Meningioma

 

Ependymomas

Gliomas

 

Meningiomas

 

Schwannomas

 

Astrocytomas

 

 

 

Q. 20 Plexiform neurofibromatosis commonly affects…

 A

Facial nerve      

 B

Trigeminal nerve

 C

Peripheral nerve

 D

Glossopharyngeal nerve

Q. 20

Plexiform neurofibromatosis commonly affects…

 A

Facial nerve      

 B

Trigeminal nerve

 C

Peripheral nerve

 D

Glossopharyngeal nerve

Ans. B

Explanation:

Ans. is ‘b’ i.e., Trigeminal nerve 


Q. 21

Musculo skeletal abnormality in neurofibromatosis is

 A

Hypertrophy of limb

 B

Scoliosis

 C

Cafe au lait spots

 D

All

Q. 21

Musculo skeletal abnormality in neurofibromatosis is

 A

Hypertrophy of limb

 B

Scoliosis

 C

Cafe au lait spots

 D

All

Ans. D

Explanation:

Ans. is `d’ i.e., All 

Quiz In Between


Q. 22

Neurofibromatosis presents as all of the following except –

 A

Elephantiasis neuromatodes

 B

Plexiform neuroma

 C

Von Recklinghausen’s disease

 D

Lymphadenovarix

Q. 22

Neurofibromatosis presents as all of the following except –

 A

Elephantiasis neuromatodes

 B

Plexiform neuroma

 C

Von Recklinghausen’s disease

 D

Lymphadenovarix

Ans. D

Explanation:

Ans. is ‘d’ i.e., Lymphadenovarix 


Q. 23

Not true regarding neurofibromatosis is ‑

 A

Never become malignant

 B

Is encapsulated

 C

Resected along nerve fibres

 D

a and b

Q. 23

Not true regarding neurofibromatosis is ‑

 A

Never become malignant

 B

Is encapsulated

 C

Resected along nerve fibres

 D

a and b

Ans. D

Explanation:

Ans is ‘a’ ie Never becomes malignant & ‘b’ i.e. is encapsulated

Malignant transformation of neurofibromas occurs in 5-10% of cases

Neurofibromatosis (or von Recklinghausens ds)

  • is the MC hereditary neurocutaneous syndrome.
  • There are two forms of neurotibromatosis, both Autosomal dominant*

Neurofibromatosis type I is characterized by :

Neurofibromatosis type II is characterized by :

numerous neurofibromas in the skin &

peripheral nerves.

the development of b/l vestibular

schwannomas in >90% of individuals*.

pigmented pathes in the skin k/a cafe au lait

spots.

pt. also has prediliction for development of

gliomas*, meningioma and schwannomas of

Freckling in non-sun exposed areas such as

 

cranial & spinal nerves.

 

the axilla.

Vestibular schwannomas (or Acoustic

hamartornas of iris termed Lisch nodules

 

neuromas)* usually present with progressive

Pseudoarthrosis of tibia.

 

deafness early in the third decade of life.

Diffuse proliferation of nerve elements may

cause massive enlargement of tissues

 

 

 

(Elephantiasis neurofibromatosa or

 

 

 

Elephant man disease)*

 

 

 

  • Schwannomas are encapsulated but neurofibromas are not Therefore Schwannomas can be resected surgically without sacrificing the nerve but in neurofibromas the nerve has to be resected along.

Difference b/w Schwannoma & Neurofibroma

  • Schwannoma (or Neurilemmoma)
  • are true encapsulated neoplasm composed of schwann cells.
  • It compresses the nerve of origin.
  • There is a plane of cleavage separating the nerve from the mass .
  • Neurofibroma
  • are unencapsulated benign neoplasm of schwann cells and fibroblasts.
  • The tumor involves the nerve. Grossly it appears as expanded nerve.
  • It is composed of mixture of schwann cell and fibroblast and contains axons within it.
  • It can not be demarcated from the nerve therefore can not be removed without sacrificing the nerve.

Q. 24 Neurofibromatosis type 2 is associated with:

 A

B/L acoustic neuroma

 B

Cafe-au-lait spots

 C

Chromosome 22

 D

All

Q. 24

Neurofibromatosis type 2 is associated with:

 A

B/L acoustic neuroma

 B

Cafe-au-lait spots

 C

Chromosome 22

 D

All

Ans. D

Explanation:

 

B/L acoustic neuromas are a hallmark of Neurofibromatosis 2

  • Neurofibromatosis Type 2 is an autosomal dominant highly penetrant condition
  • Gene for NF-2 is located on chromosome 22q.
  • Patients with NF2 present in second and third decade of life, rarely after the age of 60.
  • M/C symptom/Presenting symptom = Hearing loss
  • Skin tumors are present in nearly two thirds of patients of NF-2

-Current Otolaryngology 3/e

 


Quiz In Between


Q. 25

All of the following statements about Neurofibromatosis are true, Except:

 A

Autosomal Recessive Inheritance

 B

Cutaneous neurofibromas

 C

Cataract

 D

Scoliosis

Q. 25

All of the following statements about Neurofibromatosis are true, Except:

 A

Autosomal Recessive Inheritance

 B

Cutaneous neurofibromas

 C

Cataract

 D

Scoliosis

Ans. A

Explanation:

Answer is A (Autosomal Recessive inheritance):
Neurofibromatosis is inherited as an autosomal dominant condition

Neurofibromatosis

Oculoneurocutaneous syndrome characterized by multisystem involvement

Neurofibromatosis I (NF 1)            

Peripheral Neurofibromatosis (Von Recklinghausen’s syndrome)

•   Most prevalent type (90%)

•  Recognized to be related to abnormality of chromosome 17 (NFI gene)

•  Transmitted as an Autosomal Dominant disorder

Diagnostic Criteria for NF I

Diagnosed when any two of the following are present

1. Six more cafe-au-loit macules over 5 mm in greatest diameter in prepubertal individuals and over 15 mm in greatest diameter in post-pubertal individuals.

2. Axillary or inguinal freckling

3. Two or more iris Lisch nodules

4. Two or more neurofibromas or one plexiform neurofibroma

5. A distinctive osseous lesion such as sphenoid dysplasia or cortical thinning of long bone, with or without pseudoarthrosis.                                                          

6. Optic gliomas.

7. A first degree relative with NFI whose diagnosis was based on the aforementioned criteria.

Note

Scoliosis is the most common orthopaedic manifestation of

NFl although it is not specific enough to be included as a diagnostic criteria — Nelson 18th/2483


Neurofibromatosis II (NF II)                            

Central Neurofibromatosis (Bilateral Acoustic Neurofibromatosis)

•  Less prevalent type (10%) recognized to be related to

abnormality of chromosome 22 (NF2 gene)

•  Transmitted as an Autosomal dominant disorder

Diagnostic Criteria for NF2

 

Diagnosed when any one of the following is present.

 

1 . Bilateral eighth nerve masses consistent with acoustic

neuromas as demonstrated by CT scanning or MRI

2. A parent, sibling, or child with NF-2 and either

3. unilateral eight nerve mass or any two of the following:

– Neurofibroma

– Meningioma

– Glioma

– Schwannoma

 

Juvenile posterior subcapsular opacity

 

 

Bilateral acoustic neuromas are the most

distinctive tumors in patients with NF-2.

 

 

 

 

Note

 

Posterior subcapsular lens opacities (cataract) are

 

identified in 50% of patients with NF2

 

— Nelson 181h/2484



Q. 26 Which of the following is the most common tumor associated with type I neurofibromatosis?

 A

Optic nerve glioma.

 B

Meningioma

 C

Acoustic Schwannoma

 D

Low grade astrocytorna.

Q. 26

Which of the following is the most common tumor associated with type I neurofibromatosis?

 A

Optic nerve glioma.

 B

Meningioma

 C

Acoustic Schwannoma

 D

Low grade astrocytorna.

Ans. A

Explanation:

Answer is A (Optic Nerve Glioma):
The commonest tumor in neurofibromatosis I is optic nerve gliomna. Optic gliomas are present in approximately 15% of patients with NFI and its presence is included as one of the criteria in establishing its diagnosis.

Neoplasms associated with NF-I include:

 

CNS Neoplasms

Others tumors with higher incidence than general population

1.

Optic nerve glioma (commonest)

1.

Pheochromocytomas

2.

Meningiomas

2.

Rhabdomyosarcomas

3.

NeurojIbromas

3.

Leukaemia

4.

Schwannomas

4.

Wilm’s

5.

Astrocytomas

5.

Juvenile Xanthogranulomas

6

Neurolemmomas

 

 

 


Q. 27

Neurofibromatosis I is most commonly associated with:

 A

Brain stem gliomas

 B

Optic pathway glioma

 C

Sub ependymal pilocytic astrocytoma

 D

Glioblastoma multiforme

Q. 27

Neurofibromatosis I is most commonly associated with:

 A

Brain stem gliomas

 B

Optic pathway glioma

 C

Sub ependymal pilocytic astrocytoma

 D

Glioblastoma multiforme

Ans. B

Explanation:

Answer is B (Optic Nerve Glioma):

Optic Gliomas are present in about 15 to 25% of patient with NF-I and its presence is included as one of the criteria in establishing its diagnosis (Diagnostic criteria in NFl)

Optic Gliomas are the most common intracranial tumors of Neurofibromatosis 1- Child Neurology

Quiz In Between


Q. 28 Lisch nodules are seen in: 
March 2004

 A

Albright syndrome

 B

Neurofibromatosis

 C

Tuberous sclerosis

 D

Piebaldism

Q. 28

Lisch nodules are seen in: 
March 2004

 A

Albright syndrome

 B

Neurofibromatosis

 C

Tuberous sclerosis

 D

Piebaldism

Ans. B

Explanation:

Ans. B i.e. Neurofibromatosis

Lisch nodule

  • It is a pigmented hamartomatous nodular aggregate of dendritic melanocytes affecting the iris
  • These nodules are found in neurofibromatosis type 1, and are present in greater than 94% of patients over the age of six.
  • They are clear, yellow-brown, oval to round, dome-shaped papules that project from the surface of the iris.
  • These nodules typically do not affect vision, but are very useful in diagnosis.
  • They are detected by slit lamp examination. lmmunohistochemistry stains positive against vimentin and S-100, and points to an ectodermal origin.
  • They are not found in neurofibromatosis type 2.

Q. 29 Pheochromocytoma is usually associated with:
September 2007

 A

Pancreatic exocrine carcinoma

 B

Astrocytoma

 C

Neurofibromatosis

 D

Neuroblastoma

Q. 29

Pheochromocytoma is usually associated with:
September 2007

 A

Pancreatic exocrine carcinoma

 B

Astrocytoma

 C

Neurofibromatosis

 D

Neuroblastoma

Ans. C

Explanation:

Ans. C: Neurofibromatosis

Pheochromocytoma linked to MEN II cart be caused by RET oncogene mutations. Both syndromes are characterized by pheochromocytoma as well as thyroid cancer (thyroid medullary carcinoma). MEN IIA also presents with hyperparathyroidism, while MEN IIB also presents with mucosal neuroma.

Pheochromocytoma is also associated with neurofibromatosis


Q. 30 Lisch nodules are seen in:           
March 2009

 A

Retinoblastoma

 B

Neurofibromatosis

 C

Retiniitis pigmentosa

 D

Neuroblastoma

Q. 30

Lisch nodules are seen in:           
March 2009

 A

Retinoblastoma

 B

Neurofibromatosis

 C

Retiniitis pigmentosa

 D

Neuroblastoma

Ans. B

Explanation:

Ans. B: Neurofibromatosis

Quiz In Between


Q. 31

NOT a feature of Neurofibromatosis-1:
September2012

 A

Ash leaf spots

 B

Family history

 C

Optic glioma

 D

Axillary freckle

Q. 31

NOT a feature of Neurofibromatosis-1:
September2012

 A

Ash leaf spots

 B

Family history

 C

Optic glioma

 D

Axillary freckle

Ans. A

Explanation:

Ans. A i.e. Ash leaf spots

Dermatological conditions and important findings

Tuberous sclerosis:

– Ash leaf spot,

– Adenoma sebaceum

– Shagreen patches

  • Urticaria pigmentosa: Darrier’s sign
  • Amyloidosis: Pinch purpura
  • Lichen planus:

– Wickham’s striae,

– Civatte bodies

  • Atopic dermatitis: Dennie Morgan folds
  • Pityriasis rosacea:

– Herald patch, Mother patch

– Annular collratte of scales


Q. 32 Glioma of optic nerve is associated with ‑

 A

Neurofibromatosis type I

 B

Neurofibromatosis type II

 C

Both the above

 D

None of the above

Q. 32

Glioma of optic nerve is associated with ‑

 A

Neurofibromatosis type I

 B

Neurofibromatosis type II

 C

Both the above

 D

None of the above

Ans. A

Explanation:

Ans. is ‘a’ i.e., Neurotibromatosis type I

Optic nerve glioma

Optic nerve glioma (astrocytoma) is the most common intrinsic tumor of the optic nerve. Most common type of optic nerve glioma is juvenile pilocytic astrocytoma. The majority of optic nerve gliomas are of astrocytic origin. However, a few rare optic nerve gliomas arise from oligodendrocytes. 70% of optic gliomas occur during first decade of life. Optic nerve gliomas are associated with Neurofibromatosis-1 (Von Recklinghausen’s disease) in 55% of cases. 75% of optic gliomas arise from optic chiasma and adjacent optic nerve. 25% are confined to optic nerve alone (orbital optic nerve glioma).

Patients present with some degree of unilateral visual dysfunction, visual field loss, afferent pupillary defect, decreased ocular motility, optic atrophy, pain headache and nystagmus. Proptosis is often the chief complaint of an orbital glioma. Nystagmus may also occur. Other late features of optic nerve glioma are neovascular glaucoma, anterior segment ischemia and hemorrhagic glaucoma from retinal vascular occlusion.

In chiasmal gliomas there may be visual field defects, raised ICT, papilloedema and endocrine abnormalities like diabetes insipidus, hypopituitarism, dwarfism and precocious puberty.


Q. 33

Lisch nodule seen in ‑

 A

Sympathetic ophthalmitis

 B

Neurofibromatosis

 C

Chronic iridocyclitis

 D

Trachoma

Q. 33

Lisch nodule seen in ‑

 A

Sympathetic ophthalmitis

 B

Neurofibromatosis

 C

Chronic iridocyclitis

 D

Trachoma

Ans. B

Explanation:

Ans. is ‘b’ i.e., Neurofibromatosis
Lisch nodules are the most common type of ocular involvement in NF-1. These nodules are melanocytic hamartomas, usually clear yellow to brown, that appear as well-defined, dome-shaped elevations projecting from the surface of the iris.

Quiz In Between


Q. 34

Neurofibromatosis true is all except ‑

 A

Autosomal recessive

 B

Associated with cataract

 C

Scoliosis

 D

Multiple fibroma

Q. 34

Neurofibromatosis true is all except ‑

 A

Autosomal recessive

 B

Associated with cataract

 C

Scoliosis

 D

Multiple fibroma

Ans. A

Explanation:

Ans. is `a’ i.e., Autosomal recessive


Q. 35

Neurofibromatosis shows which of the following mode of inheritance ‑

 A

AD

 B

AR

 C

X linked dominant

 D

X linked recessive

Q. 35

Neurofibromatosis shows which of the following mode of inheritance ‑

 A

AD

 B

AR

 C

X linked dominant

 D

X linked recessive

Ans. A

Explanation:

Ans. is ‘a’ i.e., AD

Neurofibromatosis shows autosomal dominant inheritance pattern

  • Single gene disorders (Mendelian disorders) typically follow one of the three patterns of inharitance
  1. Autosomal dominance
  2. Autosomal recessive
  3. X-linked

Autosomal dominant disorders

  • Normally a gene pair has two alleles.
  • When one allele becomes abnormal due to mutation it is called heterozygous state.
  • When both the alleles become abnormal due to mutation it is called homozygous state.
  • Autosomal dominant disorders are manifested in heterozygous state, i.e. only if one allel is abnormal the disease will be manifested.

Quiz In Between



Bioterrorism Agent

Bioterrorism Agent

Q. 1 Sentinel laboratories are mainly involved in:

 A

External Quality Assessment of laboratories

 B

Diagnosis of HIV infection

 C

Control of Bioterrorism

 D

Diagnosis of Tuberculosis

Q. 1

Sentinel laboratories are mainly involved in:

 A

External Quality Assessment of laboratories

 B

Diagnosis of HIV infection

 C

Control of Bioterrorism

 D

Diagnosis of Tuberculosis

Ans. C

Explanation:

Because communication between clinical and public health laboratories is so critical in the post-2001 era, Centre for Disease Control (CDC) created an organizational structure whereby isolates and lines of communication flow freely among numbers.
The Laboratory Response Network (LRN) was originally designed as a four-tier system. Clinical laboratories (Level A) were at the bottom of a triangle, sending specimens to a public health laboratory (level B) or Level C (state public health laboratory) for confirmation.
Isolates were ultimately sent to CDC or United States Army Medical Research Institute for Infectious Diseases (USMRIID)-Level D, for archiving ang sophisticated molecular testing.
This original system has now been changed to a three-tier system in which Level A laboratories are now called Sentinel laboratories; Level B & C laboratories are called Reference laboratories & Level D are called National laboratories.
 
The main role of Sentinel Microbiology laboratories is to raise suspicion when a targeted agent is suspected in a human specimen. Detection of a possible bioterrorism event will depend on:
  •  A laboratory having an active microbial surveillance and monitoring program
  •  Vigilant technologists looking for a disease that does not occur naturally in a particular geographic region (eg: Plague in New York city); is transmitted by an aerosol route of infection; is a single case of disease caused by an unusual agent (eg: Burkholderia mallei usually only seen in the far east); Good communication with infection control practitioners, infectious disease Physicians and local or regional public health laboratories.
Ref: Bailey & Scott’s Diagnostic Microbiology; 12th edition; Page: 954-955

Q. 2

Category A bioterrorism agents are-(

 A

Ebola

 B

Yersinia

 C

Clostridium botulinum

 D

All

Q. 2

Category A bioterrorism agents are-(

 A

Ebola

 B

Yersinia

 C

Clostridium botulinum

 D

All

Ans. D

Explanation:

Ans. is ‘a’ i.e., Ebola, ‘b’ i.e. Yersinia, ‘c’ i.e. C. botulinum

Bioterrorism

.    A bioterrorism attack is the delibrate release of viruses, bacteria or other germs ( agents) used to cause illness or death in people, animals or plants. These agents are typically found in nature, but it is possible that they could be changed to increase their ability to cause disease, make them resistant to current medicines or to increase their ability to be spread into the environment. Biological agents can be spread through the air, through water or in food. Terrorists may use biological agents because they can be extermely difficult to detect and do not cause illness for several hours to several days. Some bioterrorism agents, like the small pox virus, can be spread from person to person and some like anthrax, cannot.

Bioterrorism agent categories

Category A

.   These high priority agents include organisms or toxins that pose the highest risk to the public and national security because:

i)         They can be easily spread or transmitted from person to person.

ii)       They result in high death rates and have potential for major public health impact.

iii)      They might cause public panic and social disruption.

iv)     They require special action for public health preparedness.

Category B

.  These agents are second highest priority because:

i)         They are moderately easy to spread.

ii)       They result in moderate illness rates and low death rates.

iii)      They require specific enhancements of CDC’s laboratory capacity and enhanced disease monitoring. Category C

.    These third highest priority agents include emerging pathogens that could be engineered for mass spread in the future because:

i)         They are easily available.

ii)       They are easily produced and spread.

iii)      They have potential for high morbidity and mortality rates and major health impact.

CDC Category A, B, and C Agents

Category A

Anthrax (Bacillus anthracis)

Botulism (Clostridium botulinum toxin)

Plague (Yersinia pestis)

Smallpox (Variola major)

Tularemia (Francisella tularensis)

Viral hemorrhagic fevers

Arenaviruses : Lassa, New World (Machupo, Junin, Guanarito, and Sabia)

Bunyaviridae : Crimean Congo, Rift Valley

Filoviridae : Ebola, Marburg

Flaviviridae : Yellow fever; Omsk fever; Kyasanur Forest Category B

Brucellosis (Brucella spp.)

Epsilon toxin of Clostridium perfringens

Food safety threats (e.g., Salmonella spp., Escherichia coli 0157:H7, Shigella)

Glanders (Burkholderia mallei)

Melioidosis (B. pseudomallei)

Psittacosis (Chlamydia psittaci)

Q fever (Coxiella burnetii)

Ricin toxin from Ricinus communis (castor beans)

Staphylococcal enterotoxin B

Typhus fever (Rickettsia prowazekii)

Viral encephalitis [alphaviruses (e.g., Venezuelan, eastern, and western equine encephalitis)]

Water safety threats (e.g. Vibrio cholerae, Cryptosporidium parvum) Category C

Emerging infectious diseases threats such as Nipah, hantavirus, and SARS coronoavirus.


Q. 3 Which of the following is not a group A bioterrorism agent –

 A

Small pox

 B

Hemorrhagic fever

 C

Salmonella

 D

Botulism

Q. 3

Which of the following is not a group A bioterrorism agent –

 A

Small pox

 B

Hemorrhagic fever

 C

Salmonella

 D

Botulism

Ans. C

Explanation:

Ans. is ‘c’ i.e., Salmonella

   Salmonella belongs to CDC category B.

Quiz In Between


Q. 4 Which of the following belongs to category-B of bioterrorism –

 A

Cholera

 B

Anthrox

 C

Plague

 D

Botulism

Q. 4

Which of the following belongs to category-B of bioterrorism –

 A

Cholera

 B

Anthrox

 C

Plague

 D

Botulism

Ans. A

Explanation:

Ans. is ‘a’ i.e., Cholera


Q. 5

Which amongst the following biological agents carries the highest potential for use as biological weapons for microbial bioterrorism:    
September 2012

 A

Plague (Yersinia pestis)

 B

Small pox (Variola major)

 C

Botulism (Cl. botulinum)

 D

Brucellosis (Brucella sp.)

Q. 5

Which amongst the following biological agents carries the highest potential for use as biological weapons for microbial bioterrorism:    
September 2012

 A

Plague (Yersinia pestis)

 B

Small pox (Variola major)

 C

Botulism (Cl. botulinum)

 D

Brucellosis (Brucella sp.)

Ans. A

Explanation:

Ans: A i.e. Plague (Yersinia pestis)

Bacterial pathogens and their products are potential agents of biological terrorism and biological warfare. These agents can be deployed through simple aerosol delivery systems and thereby cause widespread disease and death.

Category A: Category A agents are the highest-priority pathogens. They pose the greatest risk to national security. They include:

  • Anthrax (Bacillus anthracis)
  • Botulism (Clostridium botulinum toxin)
  • Plague (Yersinia pestis)
  • Smallpox (Variola major)
  • Tularemia (Francisella tularensis)
  • Viral hemorrhagic fevers
  • Arenaviruses: Lassa, New World (Machupo, Junin, Guanarito, and Sabia)
  • Bunyaviridae: Crimean Congo, Rift Valley
  • Filoviridae: Ebola, Marburg

Q. 6 Bioterrorism is associated with all, except  
UP 12

 A

Clostridia

 B

Chicken pox

 C

Plague

 D

Ebola virus

Q. 6

Bioterrorism is associated with all, except  
UP 12

 A

Clostridia

 B

Chicken pox

 C

Plague

 D

Ebola virus

Ans. B

Explanation:

Ans. Chicken pox

Quiz In Between


Q. 7

In the list of bioterrorism which of the following belongs to category A ‑

 A

Plague

 B

Brucella

 C

SARS

 D

E. coli 157: H7

Q. 7

In the list of bioterrorism which of the following belongs to category A ‑

 A

Plague

 B

Brucella

 C

SARS

 D

E. coli 157: H7

Ans. A

Explanation:

Ans. is ‘a’ i.e., Plague

Bioterrorism

  • A bioterrorism attack is the deliberate release of viruses, bacteria, or other germs (agents) used to cause illness or death in people, or plants. These agents are typically found in nature, but it is possible that they could be changed to increase their ability to cause disease, make them resistant to current medicine, or to increase their ability to be spread into the environment. Biological agents can be spread through the air, through water, or in food. Terrorists may use biological agents because they can be extremely difficult to detect and do not cause illness for several hours to several days. Some bioterrorism agents, like the smallpox virus, can be spread from person to person and some, like anthrax, can not.

Bioterrorism Agent Categories

  • Bioterrorism agents can be separated into three categories, depending on how easily they can be spread and the severity of illness or death they cause. Category A agents are considered the highest risk and Category C agents are those that are considered emerging threats for disease.

Category A

  • These high-priority agents include organisms or toxins that pose the highest risk to the public and national security because:
  1. They can be easily spread or transmitted from person to person
  2. They result in high death rates and have the potential for major public health impact.
  3. They might cause public panic and social disruption
  4. They require special action for public health preparedness.

Category B

  • These agetns are the second highest priority because
  1. They are moderately easy to spread
  2. They result in moderate illness rates and low death rates
  3. They require specific enhancements of CDC’s laboratory capacity and enhanced disease monitoring. Category C
  • These third highest priority agents include emerging pathogens that could be engineered for mass spread in the future because:
  1. They are easily available
  2. They are easily produced and spread
  3. They have potential for high morbidity and mortality rates and major health impact.

Q. 8 Which among the following is true about the micro-organism shown in the photomicrograph above? 

 A

Zoonotic disease.

 B

Man to man transmission possible.

 C

Agent for bioterrorism.

 D

a and c

Q. 8

Which among the following is true about the micro-organism shown in the photomicrograph above? 

 A

Zoonotic disease.

 B

Man to man transmission possible.

 C

Agent for bioterrorism.

 D

a and c

Ans. D

Explanation:

Ans:D.)Zoonotic Disease and Agent for terrorism.
The micro-organism shown in the photomicrograph above is Bacillus anthracis.

Anthrax

  • It is a zoonotic disease caused by Bacillus anthracis
  • It is primarily a disease of herbivorous – goats, sheep, cattle, horses etc.
  • Human become infected incidentally by contact with infected animals or their products.
  • B. anthracis is among the category A pathogens (ie the highest priority pathogens) for bioterrorism.
  • Antibiotic therapy is effective in humans, and ciprofloxacin is recommended for the treatment. For prophylaxis ciprofloxacin or doxycycline should be given.
  • Bacillus anthracis is very large, Gram-positive, spore-forming rod .
  • Microscopic Features:The cells have characteristic squared ends. The endospores are ellipsoidal shaped and located centrally in the sporangium. The spores are highly refractile to light and resistant to staining.
  • Mc Fadyean’s reaction is characteristic of Bacillus anthracis.

Quiz In Between



Salvage Pathway Of Purine Nucleotides

SALVAGE PATHWAY OF PURINE NUCLEOTIDES


 SALVAGE PATHWAY OF PURINE NUCLEOTIDES SYNTHESIS

  • Free purine bases and nucleosides are formed in the cell during the metabolic degradation of nucleic acids and nucleotides and then they are reused in the formation of purine nucleotides called as Salvage pathway.
  • Less energy consuming pathway.
  • It occurs in tissues like RBCs and brain.
  • Salvage Pathway Reactions-

Exam Important

  • Two main enzymes of salvage pathway are-
  1. Adenine phosphoribosyl transferase
  2. Hypoxanthine Guanine phosphoribosyl Transferase (HGPRTase)
  • Hypoxanthine to IMP by Hypoxanthine Guanine phosphoribosyl Transferase (HGPRTase)
  • Adenine to AMP by Adenine phosphoribosyl transferase
  • The end product of all purine metabolism is uric acid.
Don’t Forget to Solve all the previous Year Question asked on SALVAGE PATHWAY OF PURINE NUCLEOTIDES

Module Below Start Quiz

Factors affecting enzyme activity

Factors affecting enzyme activity

Q. 1 Enzyme activity is expressed as:

 A

Millimoles /lit?

 B

Milli gm/lit?

 C

Mg/ dl

 D

Micromoles/min

Q. 1

Enzyme activity is expressed as:

 A

Millimoles /lit?

 B

Milli gm/lit?

 C

Mg/ dl

 D

Micromoles/min

Ans. D

Explanation:

Ans. is. D. Micromoles/min


Q. 2

Which of the following leads to an increase in enzyme activity

 A

Increase in temperature

 B

Decrease in activation energy

 C

Ertremes of pH value.

 D

Low substrate concentration

Q. 2

Which of the following leads to an increase in enzyme activity

 A

Increase in temperature

 B

Decrease in activation energy

 C

Ertremes of pH value.

 D

Low substrate concentration

Ans. B

Explanation:

Quiz In Between



RNA Polymerase (RNAP)

RNA Polymerase (RNAP)

Q. 1 RNA polymerase recognizes? 
 A

Promoter site

 B Initiation site
 C Regulator site
 D Stop site
Q. 1 RNA polymerase recognizes? 
 A

Promoter site

 B Initiation site
 C Regulator site
 D Stop site
Ans. A

Explanation:

(40)        Promoter site REF: Harper 27`h ed p. 349

RNA polymerase has sigma sub unit which recognises promotor nucleotide sequence. It does not require primer and has no proof reading activity

Types:

  1. r RNA
  2. m RNA, mi RNA, Sn RNA
  3. t- RNA, 5s-rRNA, some SnRNA

Q. 2 To initiate transcription RNA polymerase does not require which one of the following:

 A

Template (ds DNA)

 B

Activated precursors (ATP, GTP, UTP, CTP)

 C

Divalent metal ions (Mn2+, Mg2+)

 D

Primer

Q. 2

To initiate transcription RNA polymerase does not require which one of the following:

 A

Template (ds DNA)

 B

Activated precursors (ATP, GTP, UTP, CTP)

 C

Divalent metal ions (Mn2+, Mg2+)

 D

Primer

Ans. D

Explanation:

DNA polymerase can only elongate existing polynucleotide chains, and thus requires a primer. RNA polymerase can initiate RNA synthesis de novo and hence does not require a primer.

Ref: Molecular Biology of the Gene Watson, 2004, Page 376 ;  Lippincott’s Illustrated Q & A Review of Biochemistry by Michael A. Lieberman, Rick Ricer, 2009, Page 294


Q. 3

The sigma (cr) subunit of prokaryotic RNA polymerase:

 A

Binds the antibiotic rifampicin

 B

Is inhibited by a-amanitin

 C

Specifically recognizes the promoter site

 D

Is part of the core enzyme

Q. 3

The sigma (cr) subunit of prokaryotic RNA polymerase:

 A

Binds the antibiotic rifampicin

 B

Is inhibited by a-amanitin

 C

Specifically recognizes the promoter site

 D

Is part of the core enzyme

Ans. C

Explanation:

C i.e. Specifically recognizes the promoter site

Quiz In Between


Q. 4

RNA polymerase does not require :

 A

Template (ds DNA)

 B

Activated precursors (ATP, GTP, UTP, CTP)

 C

Divalent metal ions (Mn2+, Mg2+)

 D

Primer

Q. 4

RNA polymerase does not require :

 A

Template (ds DNA)

 B

Activated precursors (ATP, GTP, UTP, CTP)

 C

Divalent metal ions (Mn2+, Mg2+)

 D

Primer

Ans. D

Explanation:

D i.e. Primer


Q. 5

The drug inhibiting DNA-dependent RNA polymerase in Mycobacteria is –

 A

INH

 B

Rifampicin

 C

Ciprofloxacin

 D

Ethionamide

Q. 5

The drug inhibiting DNA-dependent RNA polymerase in Mycobacteria is –

 A

INH

 B

Rifampicin

 C

Ciprofloxacin

 D

Ethionamide

Ans. B

Explanation:

Ans. is ‘b’ i.e., Rifampicin

Mechanism of action of important antitubercular drugs

o Rifampicin —> Inhibits DNA dependent RNA synthesis by inhibiting RNA polymerase.

o INH  —> Inhibits synthesis of mycolic acid which is a component of mycobacterial cell wall. o Pyrazinamide —> Inhibits synthesis of mycolic acid.

o Streptomycin —> Inhibits protein synthesis (translation).

o Ethambutol —> Inhibits incorporation ofmycolic acid into bacterial cell wall by inhibiting arbinosyltransferase.


Q. 6

RNA polymerase has which activity

 A

Primase

 B

Helicase

 C

Ligase

 D

Topoisomerase

Q. 6

RNA polymerase has which activity

 A

Primase

 B

Helicase

 C

Ligase

 D

Topoisomerase

Ans. A

Explanation:

 

DNA synthesis cannot commence with deoxyribonucleotides because DNA polymerase cannot add a mononucleotide to another mononucleotide.

  • Thus, DNA polymerase cannot initiate synthesis of complementary DNA synthesis strand of DNA on a totally single stranded template.
  • For this, they require RNA primer, which is a short piece of RNA formed by enzyme primase (RNA polymerase) using DNA as a template.
  • RNA primer is then extended by addition of deoxyribonucleotides.
  • Later on, the ribonucleotides of the primer are replaced by deoxyribonucleotides.
  • Primase is actually a DNA primase which has RNA polymerase activity. This DNA primase is also called DNA polymerase.

Quiz In Between



Post Transcriptional Modification Of Rna

POST TRANSCRIPTIONAL MODIFICATION OF RNA

Q. 1 Which of the following type of RNA has the splicing activity as a function?

 A

mRNA

 B

snRNA

 C

tRNA

 D

rRNA

Q. 1

Which of the following type of RNA has the splicing activity as a function?

 A

mRNA

 B

snRNA

 C

tRNA

 D

rRNA

Ans. B

Explanation:

Small Nuclear RNAs (snRNAs), a subset of the small RNAs, are significantly involved in rRNA and mRNA processing and gene regulation. Of the several snRNAs, U1, U2, U4, U5, and U6 are involved in intron removal and the processing of mRNA precursors into mRNA

 
Ref: Weil P. (2011). Chapter 34. Nucleic Acid Structure & Function. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper’s Illustrated Biochemistry, 29e.

 


Q. 2

A segment of an eucaryotic gene that is not represented in the mature mRNA, is known as:

 A

Exon

 B

Intron

 C

Plasmid

 D

TATA box

Q. 2

A segment of an eucaryotic gene that is not represented in the mature mRNA, is known as:

 A

Exon

 B

Intron

 C

Plasmid

 D

TATA box

Ans. B

Explanation:

Introns are the RNA sequences in the primary transcript that are not found in the mRNA. Exons RNA sequences in the primary transcript that are found in the mRNA. A TATA box is a DNA sequence that indicates the point at which a genetic sequence can be read and decoded.
 
Transcription: Transcription is the process by which DNA is copied (transcribed) to mRNA, which carries the information needed for protein synthesis. Transcription takes place in two broad steps. First, pre-messenger RNA is formed, with the involvement of RNA polymerase enzymes. Second formation of Messenger RNA.
 
Transcription unit: is a linear sequence of DNA that extends from a transcription start site to a transcription stop site. The transcription unit—that portion of a gene that is copied by RNA polymerase—consists of coding regions of DNA (exons) interrupted by intervening sequences of noncoding DNA (introns). After transcription, during RNA processing, introns are removed and the exons are ligated together to form the mature mRNA that appears in the cytoplasm.
 
1) Transcription Steps: There are three main steps to the process of DNA transcription.
  • Initiation: RNA Polymerase Binds to DNA. DNA is transcribed by an enzyme called RNA polymerase. Specific nucleotide sequences tell RNA polymerase where to begin and where to end. RNA polymerase attaches to the DNA at a specific area called the promoter region.
  • Elongation: Certain proteins called transcription factors unwind the DNA strand and allow RNA polymerase to transcribe only a single strand of DNA into a single stranded RNA polymer called messenger RNA (mRNA). The strand that serves as the template is called the antisense strand. The strand that is not transcribed is called the sense strand.
  • Termination: RNA polymerase moves along the DNA until it reaches a terminator sequence. At that point, RNA polymerase releases the mRNA polymer and detaches from the DNA.
2) Pre mRNA processing:
  • RNA splicing: pre-mRNAs typically include introns.Exons:are the continuous coding regions. Introns: are the  noncoding intervening sequences. They may serve to separate functional domains (exons) of coding information in a form that permits genetic rearrangement by recombination to occur more rapidly than if all coding regions for a given genetic function were contiguous. Introns are removed by RNA processing in which the intron is looped out and cut away from the exons by snRNPs, and the exons are spliced together to produce the translatable mRNA.
Ref: Harper’s illustrated biochemistry, 26th Edition Page  319

 


Q. 3

Poly(A) tail translates into (i.e. on translation give rise to):

 A

Polyproline

 B

Polylysine

 C

Polyalanine

 D

Polyglycine

Q. 3

Poly(A) tail translates into (i.e. on translation give rise to):

 A

Polyproline

 B

Polylysine

 C

Polyalanine

 D

Polyglycine

Ans. B

Explanation:

B i.e. Polylysine

Codon

AAA

GGG

CCC

TTT/ UUU

Translation product

LysinQ

Glycine

Proline

Phenylalanine

Quiz In Between


Q. 4 Introns are exised by

 A

RNA splicing

 B

RNA editing

 C

Restriction endonuclease

 D

DNAase

Q. 4

Introns are exised by

 A

RNA splicing

 B

RNA editing

 C

Restriction endonuclease

 D

DNAase

Ans. A

Explanation:

A i.e. RNA splicing


Q. 5

A segment of a eukaryotic gene that is not represented in the mature messenger RNA is known as:

 A

Intron

 B

Exon

 C

Plasmid

 D

TATA box

Q. 5

A segment of a eukaryotic gene that is not represented in the mature messenger RNA is known as:

 A

Intron

 B

Exon

 C

Plasmid

 D

TATA box

Ans. A

Explanation:

A i.e. Intron


Q. 6

Splicing Activity is a function of:

 A

mRNA

 B

sn RNA

 C

r RNA

 D

t RNA

Q. 6

Splicing Activity is a function of:

 A

mRNA

 B

sn RNA

 C

r RNA

 D

t RNA

Ans. B

Explanation:

B i.e. snRNA

–   Self splicing introns function as ribozyme and do not require external protein enzymes or high energy cofactors (eg ATP). Intron forms lariat in group II but not in group I self splicing introns.

–  Splicing is process of removing introns (i.e. the segment of gene that is not represented in mature m-RNA) from primary transcript and joining (or ligating together) exons (RNA sequences that code protein)Q. It is mediated by sn RNP or snrups formed from sn RNAQ.

Small nuclear RNAs (sn RNAs) are involved in RNA splicingQ; small nucleolar RNAs (sno RNAs) are involved in r RNA modificationsQ; micro RNAs (mi RNAs) & small temporal RNAs (st RNAs) are involved in inhibition (regulation) of gene expression (gene silencing)Q; small interfering RNAs (si RNAs) are involved in RNA interference (RNAi)Q; and B2 RNA binds to pol II and block transcription of many genes during heat shock

– Mammalian genomes seem to encode more non coding RNAs (nc RNAs) than coding m RNAs. nC RNAs are RNAS that do not encode proteins including r RNAS, t RNAs, mi RNAs, si RNAs, st RNAs and sn RNAs.

Quiz In Between


Q. 7 Defect in Snurps causes ‑

 A

Defect in 5′ – capping

 B

Defect in addition of poly-A tail

 C

Defect in Splicing

 D

Defect in terminal addition of nucleotide

Q. 7

Defect in Snurps causes ‑

 A

Defect in 5′ – capping

 B

Defect in addition of poly-A tail

 C

Defect in Splicing

 D

Defect in terminal addition of nucleotide

Ans. C

Explanation:

 

m-RNA processing

Prokaryotic mRNA is functional immediately upon synthesis, i.e. prokaryotic primary transcript of mRNA is functional. Thus it does not require post-transcriptional modification. In Eukaryotes the primary tran­script of mRNA is the hn RNA (hetrogeneous nuclear RNA). After transcription hnRNA is extensively modi­fied to form functional mRNA. These modifications are as follows.

1) The 5′-capping :- This is the first processing reaction. 51-end of mRNA is capped with 7-methylguansosine. This cap helps in initiation of translation (protein synthesis) and stabilizes the structure of mRNA by protecting from 5′-exonuclease.

2) Addition of poly ‘A’ tail :- As the name suggests, multiple ‘A’ (adenylate) residues are added at 3’end.This poly-A tail is not transcribed from DNA, but rather added after transcription. These tails helps to stabilize the mRNA (by protecting from 3′-exonuclease), facilitate exit from the nucleus, and aid in translation. After mRNA enters the cytosol, the poly-A tail is gradually shortened. Some mRNAs do not have poly-A tail, e.g. mRNAs of histones and some interferons.

3) Removal of introns (splicing) :- Eukaryotic genes contain some coding sequences which code for protein and some intervening non-coding sequences which do not code for protein. The coding sequences are called `exons’ and intervening non-coding sequences are called `introns’. The process by which introns are excised and exons are linked to form functional mRNA is called splicing. Thus mature mRNA does not contain introns.

  • Splicesome Splicesome is an assembly made up of small nuclear RNA (snRNA), some proteins and hnRNA. snRNA combines with proteins to form small nuclear ribnonucleoprotein particles (snRNPs or snurps) that mediate splicing. It is snRNA component of snurps that catalyzes splicing. Snurps are U4, U5 and U6.
  • Only about 1-5% of human DNA has coding sequence (exons). Remaining is non-coding (introns).

4) Alternate splicing :- The hn-RNA molecules from some genes can be spliced in alternative way in different tissues. Thus two or more different mRNA (and therefore 2 or more proteins) can be synthesized from same hnRNA. For example, difference isoforms of tropomyosin in different tissues in due to alternate splicing.


Q. 8 Defect in Snurps causes‑

 A

Sickle cell anemia

 B

Thalassemia

 C

Marfan syndrome

 D

EDS

Q. 8

Defect in Snurps causes‑

 A

Sickle cell anemia

 B

Thalassemia

 C

Marfan syndrome

 D

EDS

Ans. B

Explanation:

 

Defective splicing (defect in snurps) is the most common mutation causing thalassemia.

  • Molecular defect in pathogensis of thalassemia:‑

A) β-Thalassemia

  • Most common type of genetic abnormality in β-thalassemia is point mutation i.e., nonsense.
  • Some may also occur due to deletion or insertion i.e., frame shift mutations.
  • Defect may occur at different steps of β-chain synthesis:

i) Splicing mutations

  • Mutations leading to aberrant splicing are the most common cause of P-thalassemia.

ii) Chain terminator mutations

  • This cause premature termination of mRNA translation.

iii) Promoter region mutations

  • This results in transcription defect.

B) α-Thalassemia

  • The most common cause of reduced a-chain synthesis is deletion of a-globin genes.
  • Rarely nonsense mutation may also cause a-thalassemia.

Q. 9 Splicing is a process of ‑

 A

Activation of protein

 B

Removal of introns

 C

Synthesis of protein

 D

Replication of DNA

Q. 9

Splicing is a process of ‑

 A

Activation of protein

 B

Removal of introns

 C

Synthesis of protein

 D

Replication of DNA

Ans. B

Explanation:

 
In molecular biology and genetics, splicing is a modification of an RNA after transcription, in which introns are removed and exons are joined.

This is needed for the typical eukaryotic messenger RNA before it can be used to produce a correct protein through translation.

For many eukaryotic introns, splicing is done in a series of reactions which are catalyzed by the spliceosome a complex of small nuclear ribonucleoproteins (snRNAs), but there are also self-splicing introns.

Quiz In Between



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