Question

Processing of the mRNA begins before transcription of eukaryotic mRNA\'s is complete. The end of the mRNA is prepared for recognition by the ribosomes of the cell and protected from exonuclease degradation by a process called \"capping\". During this multi-step process a nucleoside is added to the end of the mRNA and then modified. Complete the following statements about the capping process. Capping occurs at the end of the mRNA. The nucleoside added is . The nucleoside is connected to the mRNA through a linkage. The added nucleoside is modified by methylation at atom. The mRNA is modified by methylation of ribose residues at the -hydroxy position.

Answer 1

Answer:

The correct answer is

1. 5' end.

2. guanosine

3. 5′ to 5′ triphosphate linkage.

4. On the 7th position.

5. 2′ hydroxy-groups of the first 2 ribose sugars.

Explanation:

The eukaryotic mRNA is processed or modified with a guanosine cap at 5' end and poly-A tail at 3'end before translation.

The process of adding a cap at 5' end of a growing mRNA is known as capping. The process of capping adds guanosine nucleotide at the 5'-end of mRNAs by 5′ to 5′ triphosphate linkage. This guanosine is modified by methylating at the  7th position of the atom. The mRNA is further modified by methylation of first two ribose sugars at their 2′ hydroxy-groups. This capping is advantageous to the sequence as it protects the end from phosphatases and nucleases.