The precursor of mRNA transcribed by RNA polymerase II is called heterogenous nuclear RNA (hnRNA). It undergoes following changes: (i) Splicing In this process, the non-coding introns are removed and coding sequences called exons are joined in a definite order. This is required because primary transcript contain introns and exons.
(ii) Capping RNA polymerase III is responsible for transcription of tRNA, 55 rRNA and snRNAs (small nuclear RNAs).
In capping process, an unusual nucleotide (methyl guanosine triphosphate) is added to 5?-end ofbnRNA.In tailing process, 200-300 adenylate residues are added at 3?-end in a template independent manner. It is now called as mRNA
hn RNA is heterogenous nuclear RNA.
(iii) Tailing RNA polymerase III is responsible for transcription of tRNA, 55 rRNA and snRNAs (small nuclear RNAs).
In capping process, an unusual nucleotide (methyl guanosine triphosphate) is added to 5?-end ofbnRNA.In tailing process, 200-300 adenylate residues are added at 3?-end in a template independent manner. It is now called as mRNA
hn RNA is heterogenous nuclear RNA.
(iv) The fully processed mRNA is released from the nucleus into cytoplasm for translation.
Answers
SUBRMANIYAM
The precursor of mRNA transcribed by RNA polymerase II is called heterogenous nuclear RNA (hnRNA). It undergoes following changes:
(i) Splicing In this process, the non-coding introns are removed and coding sequences called exons are joined in a definite order. This is required because primary transcript contain introns and exons.
(ii) Capping RNA polymerase III is responsible for transcription of tRNA, 55 rRNA and
snRNAs (small nuclear RNAs).
- In capping process, an unusual nucleotide (methyl guanosine triphosphate) is added to 5?-end ofbnRNA.In tailing process, 200-300 adenylate residues are added at 3?-end in a template independent manner. It is now called as mRNA
- hn RNA is heterogenous nuclear RNA.
(iii) Tailing RNA polymerase III is responsible for transcription of tRNA, 55 rRNA and snRNAs (small nuclear RNAs).- In capping process, an unusual nucleotide (methyl guanosine triphosphate) is added to 5?-end ofbnRNA.In tailing process, 200-300 adenylate residues are added at 3?-end in a template independent manner. It is now called as mRNA
- hn RNA is heterogenous nuclear RNA.
(iv) The fully processed mRNA is released from the nucleus into cytoplasm for translation.