A three-base sequence (loop) in tRNA that is complementary to a three-base sequence in mRNA is

The three-base sequence in tRNA that is complementary to a three-base sequence in mRNA is known as an "anticodon." In the process of protein synthesis, transfer RNA (tRNA) molecules play a crucial role in translating the genetic code carried by messenger RNA (mRNA). The mRNA sequence is read in sets of three nucleotides known as codons, each of which specifies a particular amino acid.

1. Anticodon Definition: The anticodon consists of three nucleotides located at one end of the tRNA molecule.

2. Complementarity: Each anticodon base pairs with the corresponding codon on the mRNA strand according to the rules of complementary base pairing. This means that adenine (A) pairs with uracil (U) in RNA (instead of thymine in DNA), and cytosine (C) pairs with guanine (G).

3. Function: This interaction ensures that the correct amino acid is brought to the growing polypeptide chain, as each tRNA molecule carries a specific amino acid that corresponds to its anticodon.

In summary, the complementary relationship between codons in mRNA and anticodons in tRNA is essential for accurately translating the genetic information encoded in DNA into functional proteins.