Final answer:
The sequence AUG is indeed the start codon, establishing the reading frame and coding for methionine in the translation process. The genetic code is universal and unambiguous, with tyrosine codons being the same in plants and humans.
Step-by-step explanation:
True, the RNA sequence AUG is considered a start codon. This start codon not only signals the beginning of translation but also codes for the amino acid methionine. The start codon establishes the reading frame, which is essential for the ribosomes to correctly read the mRNA and synthesize proteins. Once translation begins at the AUG codon, the following sets of three nucleotides (codons) are read in sequence until a stop codon is reached. These stop codons include UAG, UGA, and UAA, and they do not encode for any amino acids.
It is important to note that one codon does not encode for more than one amino acid, meaning the genetic code is unambiguous. However, the code is redundant, which means that some amino acids are coded by more than one codon. Additionally, the codons that specify for tyrosine, or any other amino acid, are universal across all living organisms, including plants and humans. Therefore, the codons for tyrosine in plants are the same as the ones in humans.