Final answer:
The three-base code in mRNA that binds to a tRNA molecule is called an anticodon.
Step-by-step explanation:
The three-base code in mRNA that binds to a tRNA molecule is called an anticodon. The anticodon is complementary to a specific codon in the mRNA sequence. Each tRNA carries a specific anticodon that can base pair with the corresponding codon on the mRNA, allowing the correct amino acid to be added to the growing polypeptide chain during protein synthesis.