In genetics, the '5' cap' is a modified guanine nucleotide added to the 5' end of eukaryotic mRNA. Its primary functions include: MCQ with Answer and Explanation

In genetics, the '5' cap' is a modified guanine nucleotide added to the 5' end of eukaryotic mRNA. Its primary functions include:
A. Splicing out introns
B. Adding the poly-A tail
C. Protecting the mRNA from degradation and facilitating ribosome binding for translation initiation
D. Terminating transcription
Answer: Option C
Solution (By JKSSB Mock Tests)
The 5' cap is a specially altered nucleotide (7-methylguanosine) attached via a 5'-5' triphosphate linkage to the 5' end of a eukaryotic mRNA molecule shortly after transcription begins. Its primary functions are to protect the nascent mRNA from degradation by 5' exonucleases, to facilitate the export of the mature mRNA from the nucleus to the cytoplasm, and, crucially, to be recognized by the eukaryotic initiation factor 4E (eIF4E), which is essential for recruiting the ribosome to the mRNA to initiate translation.

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