In which step of translation does the coding sequence conclude?

The conclusion of the coding sequence during translation occurs at the termination step. During this phase, the ribosome reaches a stop codon in the mRNA sequence, which signals the end of protein synthesis. Stop codons do not correspond to any amino acids; instead, they prompt the release factors to bind to the ribosome.

When the ribosome encounters a stop codon, it prompts the release of the newly synthesized polypeptide chain from the tRNA in the P site of the ribosome. Subsequently, the ribosomal subunits disassemble, and the mRNA is released, completing the process of translation. This step is critical because it ensures that the protein is released and can then undergo folding and post-translational modifications as necessary for its functional role within the cell.

In contrast, initiation is the step where the ribosome assembles around the start codon; elongation involves the sequential addition of amino acids to form a polypeptide chain; and activation refers to the process of amino acids being attached to tRNA molecules before translation starts. Each of these steps occurs before termination, which is why termination is the correct answer for when the coding sequence concludes.