If tRNA has an anticodon 3’ UCG 5’, which of the following is the complementary mRNA codon?

• A. 5’ AGC 3’
• B. 5’ CGA 3’
• C. 3’ AGC 5’
• D. 3’ CGA 5’

Answer: (A)

Verified step by step guidance

1. Understand the role of tRNA and mRNA in protein synthesis. tRNA carries amino acids to the ribosome and matches them to the mRNA codon using its anticodon.
2. Identify the directionality of the anticodon given: 3’ UCG 5’. This means the anticodon reads from the 3' end to the 5' end.
3. Determine the complementary base pairing rules: Adenine (A) pairs with Uracil (U), and Cytosine (C) pairs with Guanine (G).
4. Apply the base pairing rules to find the complementary mRNA codon. The anticodon 3’ UCG 5’ will pair with the mRNA codon 5’ AGC 3’.
5. Verify the directionality of the mRNA codon. The mRNA is synthesized in the 5' to 3' direction, so the complementary sequence should be 5’ AGC 3’.