Final answer:
The sequence of the start codon for translation of an mRNA is AUG, which codes for methionine and signals the beginning of protein synthesis. The ribosome scans the mRNA from 5' to 3' to find this start codon. Kozak's rules help identify the appropriate AUG codon for the initiation of translation in eukaryotes.
Step-by-step explanation:
The start codon for the translation of an mRNA is AUG. This codon not only signals the start of the translation process but also codes for the amino acid methionine. During translation, the ribosome binds to the mRNA and moves along it from the 5' to 3' direction, initiating protein synthesis at the AUG codon. Following the initiation, the mRNA is read in sets of three nucleotides at a time, and each codon specifies a particular amino acid to be added to the growing polypeptide chain. Translation continues until a stop codon (UAG, UGA, or UAA) is encountered, signaling the termination of the protein synthesis.
In eukaryotic organisms, the translation machinery, which includes initiation factors (IFs) and a cap-binding protein (CBP), locates the start codon by first binding to the 7-methylguanosine cap at the mRNA's 5' end and scanning for the first AUG codon. However, the consensus sequence around the AUG, as stated in Kozak's rules, also plays a role in determining the start site for a highly efficient translation.