Question

When RNA is processed in the nucleus and made ready for transfer out into the cytoplasm for protein synthesis, which of the following does NOT occur?
a. a ploy-A tail is added to one end
b. a guanine cap is added to one end
c. alternative splicing removes different parts of the sequence
d. introns are cut from the strand and removed
e. exons are cut from the strand and removed

Answer 1

Answer:
Letter E - exons are cut from the strand and removed

Explanation:

Letter A and B are incorrect because the poly-A tail and guanine cap are added to the 3’ and 5’ end respectively. They aid in translation of the mRNA, while serving as protection. The poly-A tail is repeated adenine nucleotides, while the guanine cap is a modified guanine nucleotide.

Letter C is incorrect because alternative splicing is one mechanism for generating variation, and is thought to be one of the reasons for why humans have smaller genomes than other organisms and still maintain high complexity. Alternative splicing is incredibly important because it produces more than one transcript from a pre-mRNA.

Letter D is incorrect because introns are the non coding portions of the mRNA. They are excised to make a smaller mRNA transcript, and one that contains all the protein genes.

This letter E is the correct answer, because exons are the coding portions of the mRNA, and are not excised during RNA processing.

Hope that helped! If I made a mistake, please let me know.