Question

A tRNA molecule has four active sites. Where are these sites and what does each do?

Answer 1

A tRNA (transfer RNA) molecule is often described as having four functional sites that allow it to act as a bridge between mRNA and proteins:

1. Amino Acid Attachment Site: Located at the 3' end (specifically the CCA sequence), this site chemically binds to a specific amino acid. Its job is to carry the “building block” to the ribosome.
2. Anticodon Site: Located at the opposite end of the anticodon loop, this site contains three bases that are complementary to an mRNA codon. Its job is to “read” the genetic message through base pairing.
3. Ribosome Recognition Site: This site helps the tRNA physically bind to the large subunit of the ribosome during translation.
4. Enzyme Recognition Site: This site is recognised by the specific enzyme aminoacyl-tRNA synthetase. Its job is to ensure the correct amino acid is loaded onto the correct tRNA molecule.