Final answer:
The movement of ribosomes that transfers tRNA from the A site to the P site and from the P site to the E site during protein synthesis is called translocation. This step is an integral part of the elongation phase of translation, which involves the addition of amino acids to the growing polypeptide chain.
Step-by-step explanation:
The movement of the ribosome that shifts the tRNA in the P site to the E site and the tRNA in the A site to the P site is called translocation. This process is crucial for the elongation phase of protein synthesis, wherein charged tRNAs sequentially enter and leave the ribosome, allowing for the successive addition of amino acids to the growing polypeptide chain. Translocation is facilitated by elongation factors like the elongation factor-G (also known as translocase), which catalyzes GTP hydrolysis, advancing the ribosome by three bases in the 3' direction along the mRNA.
Each translocation event sees the formation of a new peptide bond between the amino group of the amino acid attached to the A-site tRNA and the carboxyl group of the amino acid attached to the P-site tRNA. This enzymatic action is carried out by peptidyl transferase. Following the peptide bond formation, the A-site tRNA, now holding the growing peptide chain, moves to the P site, while the empty P-site tRNA shifts to the E site and is expelled.