Question

In which region of the t-RNA molecule is the amino-acid binding site located ?

• A. 5' end
• B. anticodon loop
• C. 3' end
• D. None of the above

Answer 1

The Correct Option is C

Transfer RNA (tRNA) molecules play a crucial role in protein synthesis by acting as adaptors between messenger RNA (mRNA) codons and amino acids. 

A tRNA molecule has a characteristic structure, often represented in 2D as a cloverleaf and in 3D as an L-shape. Key features include:

• Anticodon Loop: Contains a sequence of three nucleotides (the anticodon) that is complementary to a specific mRNA codon. This loop recognizes and binds to the codon on the mRNA molecule during translation.
• Acceptor Stem: This is a region at one end of the molecule formed by base pairing between the 5' and 3' end strands. It terminates with a specific sequence at the 3' end.
• 5' end: Typically ends with a guanine residue.
• 3' end: This end extends slightly beyond the double-helical acceptor stem and always terminates with the nucleotide sequence CCA (Cytosine-Cytosine-Adenine).

The amino acid binding site is located at the 3' end of the tRNA molecule. Specifically, the amino acid corresponding to the tRNA's anticodon is covalently attached to the terminal Adenosine residue of the CCA sequence.

Therefore, the amino-acid binding site is located at the 3' end.

Answer 2

In a tRNA molecule, the amino acid attaches to the 3' end. This end of the tRNA has a conserved CCA sequence, which is essential for the attachment of the amino acid by aminoacyl-tRNA synthetases.

The correct answer is (C) : 3' end.