Once elongation is underway, tRNAs involved in the process occupy a series of sites on the complexed ribosome. The occupation of sites occurs in the following order.

a. A Site, P Site, E Site, S Site
b. P Site, E Site, A Site
c. A Site, S Site, E Site
d. A Site, P Site, E Site

When a peptide bond is formed between two amino acids, one is attached to the tRNA occupying the P site and the other _______.

a. is free in the cytoplasm
b. Is attached to the tRNA occupying the E site
c. is attached through hydrogen bonds to the mRNA
d. is attached to the tRNA occupying the A site

Which of the following statements concerning peptide bond formation is correct?
a. It is catalyzed by an enzymatic protein.
b. It uses water
c. It requires GTP
d. It is catalyzed by peptidul transferase

1. The functional ribosome inititiation complex, have three sites that bind tRNAs: the aminoacyl (A) site, the peptidyl (P) site and the exit (E) site. Initiation occurs with binding of the fmet-tRNA at the P site. Afterwards, once elongation is underway, tRNAs involved in the process occupy the three sites in the following order: A site, P site, E site.

2. The formation of a peptide bond during protein synthesis involves the transfer of an amino acid bound to the tRNA at the P site to the amino group of a second amino acid at the A site. When a peptide bond is formed between two amino acids, one is attached to the tRNA occupying the P site and the other is attached to the tRNA occupying the A site.

3. The formation of a peptide bond during protein synthesis is catalyzed by the enzyme peptidyl transferase.