Question

How many GTPs are hydrolyzed for each amino acid incorporated into the peptide?

A) 1
B) 2
C) 3
D) 4

Answer 1

For each amino acid incorporated into a peptide during translation, two GTP molecules are hydrolyzed, one for bringing the aminoacyl-tRNA to the ribosome and the other for the translocation of the ribosome. Option B is correct.

Step-by-step explanation:

The question asks about the number of GTP molecules that are hydrolyzed for each amino acid incorporated into a peptide during the process of translation in protein synthesis. The answer is two GTPs hydrolyzed per amino acid.

During translation, there are two main steps in which GTP is utilized:

• The charging of tRNA with its corresponding amino acid (aminoacyl-tRNA) requires ATP, but there is no GTP hydrolysis in that process.
• The elongation phase of translation involves GTP hydrolysis. Firstly, the correct aminoacyl-tRNA is brought to the A-site of the ribosome. Secondly, translocation of the ribosome towards the 3' end of the mRNA requires the hydrolysis of another GTP. This means for each amino acid added to the growing polypeptide chain, two GTPs are hydrolyzed.

Thus, the correct answer to this question would be option B) 2.