Final answer:
In vertebrates and vascular plants, the AUG chosen as the start codon specifies the amino acid methionine. It also establishes the reading frame for the translation, following the consensus sequence outlined by Kozak's rules for efficient initiation.
Step-by-step explanation:
For translation in vertebrates and vascular plants, the AUG chosen as the start codon will be methionine. In both eukaryotes and prokaryotes, AUG not only codes for this amino acid but also functions as the start codon, which establishes the reading frame for translation.
The ribosome identifies the AUG start codon after the eukaryotic initiation complex recognizes the 7-methylguanosine cap at the 5' end of the mRNA and moves to this location. According to Kozak's rules, for efficient translation initiation, a consensus sequence (5'-gccRccAUGG-3') must appear around the AUG codon, where the 'R' stands for a purine (A or G).