The start codon functions by binding to the initiator tRNA (transfer RNA) that carries methionine. This interaction occurs within the ribosome, a complex molecular machine composed of rRNA and proteins. The ribosome reads the mRNA in sets of three nucleotides, known as codons, and the start codon is the first in this sequence. Once the initiator tRNA is bound, the ribosome can begin elongating the polypeptide chain by adding subsequent amino acids as dictated by the mRNA sequence.
