What defines an anticodon in relation to mRNA?

An anticodon is defined as a sequence of three bases on transfer RNA (tRNA) that is complementary to a corresponding sequence of three bases on messenger RNA (mRNA). During protein synthesis, specifically during the translation phase, the anticodon on the tRNA pairs with the codon on the mRNA strand. This pairing ensures that the correct amino acid is brought to the growing polypeptide chain, allowing for the proper synthesis of proteins according to the genetic instructions encoded in the mRNA. The specificity of this base pairing is crucial for accurately translating the genetic code into functional proteins.

The other choices do not accurately describe the function or structure of an anticodon. A sequence of four bases on mRNA does not pertain to anticodons, as anticodons consist of only three bases. A section of DNA coding for a gene refers to the DNA sequence that is transcribed into mRNA but does not represent an anticodon. Lastly, a representation of amino acids in a protein describes the overall structure of proteins rather than the specific role of anticodons in translation.