Translation Overview

The genetic code specifies unique three base sequences (called codons) for each of the 20 amino acid residues. Transfer RNA molecules (tRNAs), which are composed of a nucleic acid and a specific amino acid, provide the link between the nucleic acid sequence of messenger RNA (mRNA) and the amino acid sequence it codes for.

Each tRNA molecule for a particular amino acid contains a three nucleotide sequence, called an anticodon, which is complementary to the codon for that amino acid.

A specific enzyme called an aminoacyl-tRNA synthetase, catalyzes the attachment between each tRNA and its corresponding amino acid.

The information to be translated is carried from the cell nucleus to the cytosol by messenger RNA (mRNA). The base sequence in mRNA, in turn, is a complementary copy of the cell's DNA base sequence. For a discussion of transcription, see here.

Translation, therefore, is the conversion of the information in the nucleic acid sequence to polypeptides of a specific amino acid sequence. The process of translation requires a system to bring the mRNA together with the translating molecules (tRNAs). The system must also catalyze the polymerization of the amino acids into a polypeptide sequence.

The message in mRNAs is the sequence of nucleotide bases and is always read in the 5' to 3' direction. The polypeptide chain is made starting with the amino end of the chain first and carboxyl end of the chain last. Thus, the 5' end of the coding region of the mRNA contains the code for the amino end of the polypeptide chain.

See also: Structure of Prokaryotic mRNAs, Structure of tRNAs, Ribosomes, Initiation of Translation, Elongation of Translation, Termination of Translation

INTERNET LINKS:

> 1. Transcription/Tranlsation Summary

> 2. tRNA Synthetase Image