Final answer:
A codon is comprised of three bases, and it dictates which specific amino acid will be included in the forming protein's polypeptide chain. There are 64 possible mRNA codons, with 61 coding for amino acids and three as stop signals, and AUG additionally serving as the start codon for protein synthesis.
Step-by-step explanation:
A codon consists of three bases and specifies which amino acid will be inserted into the polypeptide chain. The genetic code is a set of rules by which information encoded in genetic material (DNA or mRNA sequences) is translated into proteins by living cells. Specifically, the genetic code is based on mRNA codons-sequentially grouped sets of three nucleotides within the mRNA molecule. Each of these triplets, or codons, corresponds to a specific amino acid or a termination signal during protein synthesis.
For instance, the mRNA codon CUA pairs with an anticodon of a tRNA molecule and corresponds to the amino acid leucine. While 64 codons exist due to the various permutations of the four nucleotide bases (A, U, G, and C), only 61 codons code for amino acids as the remaining three are stop codons signaling the end of polypeptide synthesis.
The AUG codon serves a dual function. It's a start signal for translation and also encodes for the amino acid methionine. All of these interactions ensure proteins are synthesized correctly, following the precise sequence of amino acids as dictated by the genetic code present in the mRNA.