Question

please write 3 paragraph about 5 cap and explain it

Answer 1

Ans-

5' capping is mRNA protection process which is typically seen in eukaryotes. It consist of guanine nucleotide which is link to mRNA via 5'-5' triphosphate linkage. The guanosine nucleotide at 7 position is attached with methyl group. Therefore the 5' cap is also known as 7-methyl guanosine cap. The addition of methyl group to the nucleotide is catalyzed via enzyme known as methyltransferase. In sn RNA there is 5'trimethyl guanosine cap also present. The attachment of 5' cap is carried in sequential manner.

Firstly, the terminal phosphate group is removed leaving bisphosphate group, this reaction is catalyzed by RNA triphosphatase. Followed by addition of GTP by mRNA guanylyltransferase. thus leading to the formation of 5'-5' triphosphate linkage. Further methyltransferase add methyl group at 7 position of nucleotide.

The capping of mRNA helps to regulate various process in the cell. In eukaryotes translation and transcription is carried out separately. Hence, it is important for the mRNA to be transported out of the nucleus. The 5' cap helps in export of mRNA from the nucleus. It also prevent the mRNA from exonuclease degradation. Exonuclease are the enzyme which cleaves at the end of nucleotide sequence. The capping prevents the cleavage of nucleotide from the exonuclease. It help in recognition site for translation.