Question

Which of the following are the post-transcriptional events in an eukaryotic cell?

1. Transport of pre-mRNA to cytoplasm prior to splicing.
2. Removal of introns and joining of exons.
3. Addition of methyl group at 5' end of hnRNA.
4. Addition of adenine residues at 3' end of hnRNA.
5. Base pairing of two complementary RNAs.

Choose the correct answer from the options given below:

Options

• A, B, C only

• B, C, D only

• B, C, E only

• C, D, E only

Answer 1

B, C, D only

Explanation:

In eukaryotic cells, post-transcriptional modifications occur after transcription but before the mRNA is translated. These include:

• Capping: The 5' end of the mRNA is given a 5' cap, which is usually a modified guanine nucleotide. This cap is recognised by the translation machinery, helps export mRNA from the nucleus, and shields it from degradation.
• Splicing: The pre-mRNA is divided into coding sequences (exons) and non-coding sequences (introns). The creation of mature mRNA molecules depends on this process, which is called RNA splicing.
• Polyadenylation: The 3' end of the mRNA is extended with a poly(A) tail, which is a lengthy chain of adenine nucleotides. This tail aids the export of mRNA from the nucleus and contributes to its stability.
• RNA Modification: The RNA sequence can undergo a number of chemical alterations, such as methylation, pseudouridylation, and other modifications that can modify the structure and functionality of RNA.