What is the group of three bases on a tRNA molecule that are complementary to an mRNA codon called?

• A. Anticodon
• B. Codons
• C. mRNA
• D. tRNA

Answer: (A)

During translation, the three-nucleotide region on a tRNA that recognizes a specific codon on mRNA is called the anticodon. This anticodon pairs with the corresponding codon on the mRNA through complementary base pairing (A pairs with U, G with C) in an antiparallel orientation, so the tRNA brings the correct amino acid for incorporation into the growing protein. This pairing is what translates the genetic code into a sequence of amino acids. The other terms refer to parts of the mRNA or the tRNA molecule itself, not the recognition site on tRNA: codons are on mRNA, mRNA is the template, and tRNA is the adaptor molecule that carries amino acids.