Definition of translation and gene expression

Summary

Translation is the biological process in which cells produce proteins using RNA as a template. In this process, messenger RNA (mRNA) is decoded by ribosomes outside the nucleus to build a polypeptide chain (a sequence of amino acids). The mRNA nucleotide sequence is read in three-nucleotide units (codons), and each codon specifies a particular amino acid according to the genetic code. Transfer RNAs (tRNAs) bring the correct amino acids to the ribosome by base-pairing their anticodons with mRNA codons, allowing amino acids to be linked into a growing chain. Gene expression is the overall process that includes translation as one of its major steps. After translation, the polypeptide folds into an active protein that performs cellular functions; folding can begin during synthesis. Translation proceeds through initiation, elongation, and termination, with ribosomes using specialized binding sites (A and P/E) and release factors at stop codons to complete protein synthesis. Thus, translation converts genetic information carried by RNA into functional proteins, and gene expression describes the full pathway from gene information to protein output.

Key Points

• 1

  Translation converts the nucleotide sequence of mRNA into an amino acid sequence (polypeptide) using ribosomes and tRNAs.

• 2

  The genetic code links each mRNA codon (three nucleotides) to a specific amino acid, enabling stepwise protein synthesis.

• 3

  Gene expression encompasses translation and results in a functional protein after the polypeptide is synthesized and folds.