Which of the following represents an mRNA codon?

The correct choice, which is UAU, represents an mRNA codon because it consists of a sequence of three nucleotides that corresponds to a specific amino acid during the process of translation. Codons are critical for the genetic code because they determine which amino acids are added to a growing polypeptide chain based on the mRNA template.

Each codon is composed of three nucleotides, and in this case, UAU codes for the amino acid tyrosine. The significance of this lies in how mRNA, transcribed from DNA, is read by ribosomes to synthesize proteins. Codons directly relate to how genetic information is translated into functional proteins.

The other sequences, while they are valid three-nucleotide sequences, do not fulfill the requirement of representing a specific codon for an amino acid in the context of the question. For example, AUG is known as a start codon, which initiates protein synthesis but is not classified in the same category as UAU as a functional amino acid codon during general reference. ACG is a codon that codes for threonine, while UAA is a stop codon, signaling the termination of protein synthesis. Each plays a different role in protein synthesis, but UAU