Translatie

Translatie is, commonly referred to as translation, the process by which ribosomes synthesize proteins by decoding messenger RNA (mRNA) sequences into polypeptide chains. It is a central step in gene expression and occurs in all living cells, following transcription.

The process proceeds through initiation, elongation, and termination. Initiation involves assembly of the ribosome with the mRNA and an initiator tRNA carrying the first amino acid. In bacteria, a ribosomal binding site on the mRNA helps align the start codon with the ribosome; in eukaryotes, initiation typically begins at the 5' cap and proceeds by scanning to the first AUG. During elongation, aminoacyl-tRNA molecules deliver specific amino acids to the ribosome, matching codons on the mRNA with anticodons on tRNA. The ribosome catalyzes peptide bond formation, and the ribosome translocates along the mRNA, aided by elongation factors and hydrolysis of GTP. Termination occurs when a stop codon is encountered; release factors promote release of the finished polypeptide and ribosome recycling.

Key components are the ribosome, messenger RNA, and transfer RNAs, along with various initiation, elongation, and release factors. The genetic code is nearly universal, with codon triples specifying amino acids; translation fidelity is maintained by base-pairing rules and proofreading activity within the ribosome, which serves as a ribozyme in its catalytic center.

Beyond synthesis, the polypeptide may fold with the help of chaperones and undergo folding and post-translational modifications to become a functional protein. Translation regulation integrates cellular signals and can be targeted by antibiotics that disrupt bacterial ribosomes.