Elongation factor G primarily helps with what? a. Catalyzing the formation of th

Question

Elongation factor G primarily helps with what?

a. Catalyzing the formation of the peptide bond between consecutive amino acids

b. Editing mismatched tRNA’s and amino acids

c. Guiding the nascent polypeptide chain out of the ribosome

d. Aiding the translocation of the ribosome by 3 nucleotides so the tRNA in the A site moves to the P site

In what order do tRNA’s bound to amino acids visit the three binding sites in a ribosome (with the exception of the first amino acid in the chain)?

a. E (exit), P (peptidyl), A (aminoacyl)

b. P (peptidyl), E (exit), A (aminoacyl)

c. P (peptidyl), A (aminoacyl), E (exit)

d. A (aminoacyl), P (peptidyl), E (exit)

e. A (aminoacyl), E (exit), P (peptidyl)

Explanation / Answer

1) Option d is the correct answer.

Elongation factor G primarily helps with the translocation of the ribosome by 3 nucleotides so the tRNA in the A site moves to the P site. It promotes the the movement of the tRNA-peptidyl-tRNA-mRNA complex from the pre- to the post-translocation position after a peptide bond has been formed. Following termination, which entails the hydrolytic release of the completed nascent peptide from P site-bound peptidyl-tRNA and results in a ribosome with deacylated tRNA in the P site and an empty A site.

2) Option d is correct answer.

tRNA’s bound to amino acids visit the three binding sites in a ribosome in the order of A (aminoacyl), P (peptidyl), E (exit). The initiator methionyl tRNA is bound at the P site. The first step in elongation is the binding of the next aminoacyl tRNA to the A site by pairing with the second codon of the mRNA. A peptide bond is then formed, resulting in the transfer of methionine to the aminoacyl tRNA at the A site. The ribosome then moves three nucleotides along the mRNA. This movement translocates the peptidyl tRNA to the P site and the uncharged tRNA to the E site, leaving an empty A site ready for addition of the next amino acid.

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.