Question

When one speaks of a 5' cap, one is describing the addition of a base, usually thymine, to the 5' end of a completed peptide.

A) True
B) False

Answer 1

A 5' cap refers to the addition of a base, usually thymine, to the 5' end of a completed peptide.

Step-by-step explanation:

A 5' cap refers to the addition of a base, usually thymine, to the 5' end of a completed peptide.

However, the information provided in the reference sources suggests that this statement is false. A 5' cap is actually the addition of a 7-methylguanosine cap to the 5' end of mRNA during its synthesis. This cap protects the mRNA from degradation and helps initiate translation by ribosomes.

Answer 2

The statement is false as a 5' cap refers to the addition of a 7-methylguanosine cap to the 5' end of pre-mRNA, not a peptide, and involves guanine, not thymine.

Step-by-step explanation:

The statement that a 5' cap involves the addition of a base, usually thymine, to the 5' end of a completed peptide is false. In actuality, the 5' capping process involves the enzymatic addition of a 7-methylguanosine cap to the 5' end of a growing pre-mRNA transcript—not a peptide—and this process occurs in the nucleus. The 5' cap, which consists of a methylated guanosine triphosphate (GTP) molecule, protects the mRNA from degradation and plays a critical role in subsequent protein synthesis by aiding in the initiation of translation when the mRNA reaches the ribosomes in the cytoplasm.