Final answer:
The second step of protein synthesis is translation, which consists of initiation, elongation, and termination phases. It begins with the formation of an initiation complex and is followed by the elongation of the polypeptide chain, ending with termination when a stop codon is encountered.
Step-by-step explanation:
The second step of protein synthesis is translation. During translation, tRNA and mRNA work together to build amino acids into polypeptide chains. This process follows three phases: initiation, elongation, and termination.
- Initiation of Translation
Initiation begins with the formation of an initiation complex. This complex includes the small ribosomal subunit, the mRNA template, initiation factors, and a special initiator tRNA called tRNAMet. The tRNAMet carries the amino acid methionine and pairs with the start codon AUG on the mRNA strand.
- Elongation and Termination
Elongation is the addition of amino acids to the growing polypeptide chain, which occurs at specific sites (A, P, and E) on the ribosome. Termination occurs when a stop codon is reached, signaling the end of the polypeptide chain synthesis, and the complete protein is then released from the ribosome.