Which process directs the formation of a specific protein at a ribosome?

The process that directs the formation of a specific protein at a ribosome is translation. This is the final step in gene expression, where the information encoded in mRNA (which is transcribed from DNA) is read by the ribosome to synthesize a particular protein.

During translation, ribosomes facilitate the binding of transfer RNA (tRNA) molecules to the mRNA strand, allowing the amino acids they carry to be linked together in the correct sequence as specified by the mRNA. The ribosome essentially acts as a molecular machine that assembles the amino acids into a polypeptide chain, ultimately folding into a specific functional protein that can perform various roles within the cell.

The other processes listed do not directly create proteins. Replication is the process of copying DNA for cell division, and transcription refers to the synthesis of mRNA from DNA. Initiation alone does not encompass the entire process of protein synthesis but instead refers to the very beginning stages of translation or transcription. Thus, translation is the correct choice as it completes the protein synthesis process at the ribosome.