The main function of tRNA (transfer RNA) in protein synthesis is to decode mRNA codons and deliver the corresponding amino acids to the ribosome, where they are added to the growing polypeptide chain.
Here's a more detailed breakdown:
tRNA's Role in Translation
During translation, which is the process of protein synthesis, tRNA molecules act as adaptors. They link the genetic code (mRNA) to the amino acid sequence of a protein. Here's how:
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Codon Recognition: Each tRNA molecule has a specific three-nucleotide sequence called an anticodon. This anticodon is complementary to a specific three-nucleotide sequence on the mRNA molecule called a codon. The anticodon on the tRNA binds to the codon on the mRNA, ensuring the correct amino acid is added to the growing polypeptide chain.
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Amino Acid Delivery: Each tRNA molecule is also attached to a specific amino acid that corresponds to its anticodon. When the tRNA anticodon binds to the mRNA codon in the ribosome, it delivers its amino acid. The ribosome then catalyzes the formation of a peptide bond between this amino acid and the previous amino acid in the chain, elongating the protein.
The tRNA Structure
The tRNA molecule has a characteristic cloverleaf shape due to internal base pairing. Key structural features include:
- Anticodon Loop: Contains the anticodon sequence for recognizing mRNA codons.
- Amino Acid Acceptor Stem: The site where the specific amino acid is attached.
Summary
In essence, tRNA acts as a crucial intermediary, bridging the gap between the genetic information encoded in mRNA and the amino acid building blocks that form proteins. It ensures the correct amino acid sequence is assembled based on the mRNA's instructions.
