Question

In completing protein synthesis in a prokaryote, what basic message is carried by a specialized codon that has no corresponding tRNA?

1) Fold peptide chain.
2) Terminate here.
3) Add cofactor.
4) Clip starting amino acid.

Answer 1

A specialized codon with no corresponding tRNA in prokaryotic protein synthesis signals 'terminate here', which are known as stop codons, and they trigger the release of the polypeptide chain from the translation machinery.

Step-by-step explanation:

The basic message carried by a specialized codon in protein synthesis that has no corresponding tRNA is to terminate here. In prokaryotic translation, such as in E. coli, three of the 64 possible mRNA codons are earmarked for this role; these are UAA, UAG, and UGA. They are known as stop codons or nonsense codons, and they signal the end of protein synthesis, triggering the release of the newly formed polypeptide chain from the translation machinery. Unlike the rest of the codons, which specify the addition of a particular amino acid to the growing polypeptide chain, stop codons do not code for an amino acid and have no corresponding tRNA. Instead, when a stop codon is encountered during translation, release factors bind to the ribosome and facilitate the termination process and the disassembly of the translation complex.