Final answer:
The central reaction of protein synthesis involves the formation of a peptide bond between two amino acids within the ribosome, catalyzed by peptidyl transferase, without the need for external energy. Aminoacyl-tRNA synthetase enzymes link amino acids to tRNAs, and the translation process continues until reaching a stop codon, resulting in a synthesized protein.
Step-by-step explanation:
The central reaction of protein synthesis, also known as the transpeptidation reaction, is the biochemical process by which the peptide bond is formed between two amino acids during the translation phase of protein synthesis. This reaction takes place within the ribosome, a complex molecular machine found within all living cells. The ribosome facilitates the formation of a peptide bond through a nucleophilic acyl substitution mechanism, catalyzed by the ribosomal enzyme known as peptidyl transferase. Aminoacyl-tRNA synthetase enzymes first link amino acids to their respective tRNA molecules, a critical step before the peptide bond formation. During translation, the amino group of an amino acid attached to the A-site tRNA reacts with the carboxyl group of the amino acid attached to the P-site tRNA, forming the peptide bond and elongating the growing polypeptide chain. This process requires no external energy input because the ester linking the peptidyl moiety to tRNA is intrinsically reactive. The synthesis of peptides continues until a stop codon is reached, concluding the translation process and releasing the newly synthesized protein, which may undergo further post-translational modifications to become fully functional.