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Multiple Choice
Which of the following statements about the 5' ends of RNA polymers is correct?
A
The 5' end of RNA is always unmodified and free.
B
The 5' end of RNA is capped with a methylated cytosine.
C
The 5' end of RNA is capped with a poly-A tail.
D
The 5' end of RNA is capped with a modified guanine nucleotide.
Verified step by step guidance
1
Understand the structure of RNA: RNA is a nucleic acid similar to DNA, but it is typically single-stranded and contains ribose sugar and uracil instead of thymine.
Learn about RNA processing: In eukaryotic cells, the primary RNA transcript undergoes several modifications before becoming mature mRNA. One of these modifications occurs at the 5' end.
Explore the 5' capping process: The 5' end of the nascent RNA transcript is modified by the addition of a cap. This cap is a modified guanine nucleotide, specifically 7-methylguanylate, which is added shortly after transcription begins.
Understand the purpose of the 5' cap: The 5' cap protects the RNA from degradation, assists in ribosome binding during translation, and is involved in the export of the RNA from the nucleus.
Evaluate the given statements: Compare each statement with the knowledge of RNA capping. The correct statement is that the 5' end of RNA is capped with a modified guanine nucleotide, which aligns with the known biological process of 5' capping.