Final answer:
In eukaryotes, the ribosome uses the AUG codon it encounters in an mRNA as a signal to start translation.
Step-by-step explanation:
In eukaryotes, the ribosome recognizes the 7-methylguanosine cap at the 5' end of the mRNA and tracks along the mRNA until it finds the start codon AUG. The AUG codon is commonly used as the start signal for translation, and it codes for the amino acid methionine. However, the efficiency of translation can be influenced by the sequence of nucleotides around the AUG codon.
Kozak's rules state that a consensus sequence, 5'-gccRccAUGG-3', should appear around the AUG for optimal translation efficiency. The R represents a purine base, either A or G. The process begins with the recognition of the 7-methylguanosine cap at the 5' end of mRNA by cap-binding proteins and the initiative complex then scans for the start codon in a 5' to 3' direction.