Question

Which amino acid will be charged on the tRNA with anticodon 5Õ-GUU-3Õ?

• A. Asparagine (codon AAC)
• B. Valine (codon GUU)
• C. Leucine (codon UUG)
• D. Glutamine (codon CAA)

Hint:

Always write out the $5'$ and $3'$ ends explicitly when pairing codon and anticodon.
$5'\text{-GUU-}3'$ (anticodon) pairs with $3'\text{-CAA-}5'$ (codon), which is read as $5'\text{-AAC-}3'$ (Asparagine) from left to right.

Answer 1

The Correct Option is A

Step 1 : Understanding the Question:
The question asks us to identify which amino acid is attached to a tRNA molecule that possesses the anticodon sequence $5'\text{-GUU-}3'$.

Step 2 : Key Formulas and Approach:
The approach is based on the rules of complementary, antiparallel base pairing between the mRNA codon and the tRNA anticodon during translation.
Nucleic acid strands always align antiparallel to each other ($5'\rightarrow 3'$ pairs with $3'\rightarrow 5'$).

Step 3 : Detailed Explanation:

• tRNA Anticodon: The given sequence is $5'\text{-G-U-U-}3'$.

• Complementary base-pairing rules:
• G pairs with C

• U pairs with A

• U pairs with A

• Determining mRNA Codon: Writing the complementary partners in the antiparallel direction gives:
$3'\text{-C-A-A-}5'$

• Standard Direction: We write the mRNA codon in the standard $5'\rightarrow 3'$ direction:
$5'\text{-A-A-C-}3'$ (or simply AAC)

• Amino Acid Assignment: The genetic code table is based on mRNA codons.
The codon $5'\text{-AAC-}3'$ specifically codes for the amino acid Asparagine.

Step 4 : Final Answer:
Therefore, the tRNA with the anticodon $5'\text{-GUU-}3'$ will carry the amino acid Asparagine, corresponding to Option (A).