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Multiple Choice
Which of the following modifications occur to a eukaryotic pre-mRNA?
A
Conversion to DNA
B
Addition of a 5' cap
C
Addition of a poly-A tail at the 5' end
D
Removal of exons
Verified step by step guidance
1
Understand that eukaryotic pre-mRNA undergoes several modifications before becoming mature mRNA, which is ready for translation.
Recognize that one of the key modifications is the addition of a 5' cap. This involves adding a modified guanine nucleotide to the 5' end of the pre-mRNA, which helps protect the mRNA from degradation and assists in ribosome binding during translation.
Another important modification is the addition of a poly-A tail. This involves adding a series of adenine nucleotides to the 3' end of the pre-mRNA, which also helps stabilize the mRNA and facilitate its export from the nucleus.
Understand that introns, not exons, are removed during RNA splicing. Exons are the coding regions that are joined together to form the final mRNA sequence.
Note that conversion to DNA is not a modification of pre-mRNA. Pre-mRNA is transcribed from DNA, but it is not converted back into DNA during processing.