Question

What are the functions of
a) Methylated guanine cap?
b) Poly-A tail on a mature RNA?

Answer 1

Hint: Transcription is the process in which the genetic information is copied into RNA from one strand of the DNA. Transcription is also governed by the principle of complementarity like replication however, during transcription only a small segment of DNA is copied.

Complete step-by-step answer:
a) Functions of the methylated guanine cap: The process of transcription in eukaryotes is carried out in three steps. The methylated guanine cap plays an important role in the first step usually. That is why the first step is the modification of the 5’ end by capping. The capping at the 5’ end occurs rapidly after the transcription. Methyl guanosine triphosphate nucleotide is added to the 5’ end of the hnRNA. This cap is essential for the formation of the mRNA-ribosome complex. The process of translation is not possible if the cap is lacking because it is identified by the 18S unit of the ribosome of rRNA.

b) Functions of the Poly-A tail on a mature RNA: The second step is tailing. Tailing is the addition of the adenylate residues. About 200-300 adenyl groups are attached at the 3’ end of the newly formed hnRNA, with the help of Poly A polymerase. This tail makes the RNA molecule more stable and prevents it from degradation.

Note: The process of copying the genetic information from one strand of the DNA to the RNA is known as transcription. The process of the transcription is governed by the same complementary base pair rules as DNA replication. The only difference is that adenosine forms the base pair with uracil instead of thymine, in the process of transcription.