Which process occurs at ribosomes and specifies the sequence of amino acids in polypeptide chains?

The process that occurs at ribosomes and specifies the sequence of amino acids in polypeptide chains is translation. During translation, messenger RNA (mRNA) is decoded by ribosomes to synthesize proteins. The ribosome reads the sequence of nucleotides in the mRNA in sets of three, known as codons, each of which specifies a particular amino acid. As tRNA molecules bring the appropriate amino acids to the ribosome, they bind to the mRNA according to the codon-anticodon pairing rules, thus forming a polypeptide chain. This process is crucial because it translates the genetic information encoded in the mRNA into functional proteins, which play vital roles in the cell and the organism as a whole.

In contrast, transcription refers to the synthesis of RNA from a DNA template and occurs in the nucleus, while replication involves copying DNA to ensure that each new cell has the same genetic information. Translocation typically refers to the movement of chromosomes during cell division, not the synthesis of proteins. Therefore, translation is the correct answer, emphasizing the ribosome's role in assembling amino acids into a specific sequence based on the mRNA template.