Amino acids are brought to the cellular site of translation, which occurs at the ribosome, by molecules called transfer RNA (tRNA). Each tRNA molecule carries a specific amino acid and has a region called the anticodon that is complementary to the codon on the mRNA (messenger RNA).
Process of Amino Acid Transport to the Ribosome:
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Aminoacyl-tRNA Synthetase: Each amino acid is attached to its corresponding tRNA by an enzyme called aminoacyl-tRNA synthetase. This enzyme catalyzes the reaction that covalently links the amino acid to the appropriate tRNA molecule.
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Transport to the Ribosome: Once the tRNA is charged with its amino acid (a process called "aminoacylation"), the tRNA travels to the ribosome, where translation takes place.
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Translation: At the ribosome, the mRNA is read in sets of three nucleotides called codons. Each codon specifies a particular amino acid. The tRNA has an anticodon region that is a complementary sequence to the codon on the mRNA. This allows for the correct pairing between the tRNA and the mRNA, ensuring that the appropriate amino acid is added to the growing polypeptide chain.
Anticodon:
The anticodon is a sequence of three nucleotides found on the tRNA that pairs with the corresponding codon on the mRNA during translation. For example, if the mRNA codon is AUG (which codes for methionine), the tRNA will have the anticodon UAC. This base-pairing ensures that the correct amino acid is inserted into the polypeptide according to the sequence of the mRNA. Each tRNA molecule has a unique anticodon that corresponds to a specific codon on the mRNA, allowing for the proper translation of the genetic code into proteins.