Structure Of Rna

D i.e. A single strand of DNA

D i.e. Deamination

Ribozyme is RNA with catalytic activityQ. Examples include selfsplicing group I introns, RNase P, & hammerhead metallo enzymeQ of virusoids (requiring Mg²⁺). These are involved in transesterification, phosphodiester bond hydrolysis (cleavage), RNA metabolism (splicing & endoribonuclease), peptide bond formation (peptidyl transferases) and site specific RNA cleavage.

A i.e. AUG Codon

Ans. is ‘b’ i.e., Stabilization of mRNA

At the 5¹-end, mRNA possesses a 7-methylguanosine triphosphate cap which helps in the recognition of mRNA in protein biosynthesis and it helps to stabilize the mRNA by preventing attack of 5¹-exonuclease.

At its 3¹-end, there is a poly-A tail made up of several adenylate residues which stabilize mRNA by preventing attack of 3¹-exonuclease.

t-RNA molecule get folded into a structure that appears like a clover leaf.

There are four arms.

1. Acceptor arm : It consists of a base paired stem that terminates in the sequence CCA at the 3′ end. This is the attachment site for amino acids.
2. D arm – It contains the base dihydrouridine (D).
3.  Anticodon arm – It contains anticodon that base pairs with the codon of coming mRNA. Anticodon has nucleotide sequence complementary to the codon of mRNA and is responsible for the specificity of the t RNA.
4. Tyr C arm : It contains both ribothymidine (T) and pseudouridine

“The CCA tail is a CCA sequence at 3′ end of the tRNA molecule. In prokaryotes, CCA sequence is transcribed. In eukaryotes, the CCA sequence is added during processing”.

“tRNA is the smallest of three major species of RNAs”   — Dinesh puri

tRNA comprises 15% of total RNA in the cell. It contains 73-93 nucleotide residue.

Ans. a. Bacteria

Both DNA and RNA are pre sent in Bacteria

Ans. is ‘c^‘ i.e., Nucleolus 

Ans. is ‘c’ i.e., m RNA

The m RNA carries genetic information in the form of codons.

• Codons are a group of three adjacent nucleotides that code for the amino acids of protein.
• Each mRNA molecule is a transcript of antisense or template strand of a particular gene.
• Its nucleotide sequence is complementary to that of antisense or template strand of the gene, i.e. adenine for thyamine, guanine for cytosine, uracil for adenine (as RNA does not contain thymine) and cytosine for guanine.
• For example, if antisense strand of DNA has a gene with sequence 5′-TTACGTAC-3′, its complementary RNA transcript will be 5 ‘-GUACGUAA-3’.

Ans. is `d’ i.e., All of the above

• mRNA is synthesized from DNA by the process of transcription in the nucleus. 
• After formation mRNA transport out of the nucleus into cytoplasm.
• t-RNA is also synthesized in nucleus and is transported to cytoplasm.
• Protein synthesis (translation) occurs in ribosomes, and requires both mRNA and tRNA.
• rRNA is present in ribosomes.
• rRNA is synthesized in nucleolus

Thus, RNA can be found in –

1. Nucleus
2. Cytoplasm
3. Ribosome
4. Nucleolus