Mention the role of the codons AUG and UGA during protein synthesis.

During protein synthesis, codons play a crucial role in determining which amino acids are added to the growing polypeptide chain. The codon AUG serves two important roles: Start Codon: AUG serves as the start codon for protein synthesis in most organisms. It signals the initiation of translation and the assembly of the ribosome-mRNA complex. The initiation process begins when the small ribosomal subunit binds to the mRNA at the AUG start codon, and then the initiator tRNA carrying the amino acid methionine binds to this codon. This marks the beginning of translation, with subsequent amino acids being added to the growing polypeptide chain. Methionine: In addition to signaling the start of translation, AUG codes for the amino acid methionine. However, in many cases, this methionine is removed later from the mature protein after translation is completed. On the other hand, UGA serves as a stop codon during protein synthesis. Stop codons signal the termination of translation and the release of the newly synthesized polypeptide chain from the ribosome. When the ribosome encounters a UGA codon, a release factor binds to the ribosome, causing the hydrolysis of the bond between the completed polypeptide chain and the tRNA molecule, leading to the release of the protein. read less