Catabolism of carbon skeleton of amino acids

Catabolism of carbon skeleton of amino acids

Q. 1

Which of the following is not synthesised from tyrosine?

 A

Norepinephrine

 B

Melatonin

 C

Thyroxine

 D

Dopamine

Q. 1

Which of the following is not synthesised from tyrosine?

 A

Norepinephrine

 B

Melatonin

 C

Thyroxine

 D

Dopamine

Ans. B

Explanation:

Q. 2

Which of the following is derived from tyrosine ‑

 A

Melatonin

 B

Serotonin

 C

Melanin

 D

Niacin

Q. 2

Which of the following is derived from tyrosine ‑

 A

Melatonin

 B

Serotonin

 C

Melanin

 D

Niacin

Ans. C

Explanation:

Ans. is ‘c’ i.e., Melanin

Tyrosine is a precursor of many important compounds such as catecholamines (epinephrine, norepinephrine ), dopamine), thyroxine, triiodothryonine, melanin.


Q. 3

Enzyme deficient in tyrosinemia type 1 ‑

 A

Phenylalanine hydroxylase

 B

Tyrosinase

 C

Fumarylacetoacetate hydroxylase

 D

Tyrosine transaminase

Q. 3

Enzyme deficient in tyrosinemia type 1 ‑

 A

Phenylalanine hydroxylase

 B

Tyrosinase

 C

Fumarylacetoacetate hydroxylase

 D

Tyrosine transaminase

Ans. C

Explanation:

 

Tyrosinemia

It is a defect in metabolism of tyrosine. It may be of following types :-

  1. Tyrosinemia type-I (tyrosinosis/hepatorenal syndrome) :- It is due to defect in fumarylacetoacetate hydroxylase deficiency. Patients with chronic tyrosinosis are prone to develop cirrhosis and hepatic carcinoma. There is cabbage like odor in acute tyrosinosis.
  2. Tyrosinemia type – II (Richer-Hanhart syndrome) :- It is due to deficiency of tyrosine transaminase (tyrosine aminotrans-ferase).
  3. Neonatal tyrosinemia : – It is due to deficiency of hydroxyphenyl pyruvate hydroxylase.

Quiz In Between



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