Translation is the process by which ribosomes synthesize a polypeptide from a messenger RNA template, using transfer RNAs to deliver amino acids in the order specified by codons.
Explanation
Translation is a fundamental step of gene expression linking nucleic acid information to proteins. In bacteria it begins when the small ribosomal subunit binds to a ribosome‑binding site in the mRNA and an initiator tRNA carrying N‑formylmethionine pairs with the AUG start codon. In eukaryotes initiation factors recruit the small ribosomal subunit to the 5′ cap and it scans to the first suitable AUG within a Kozak consensus sequence. Once the start codon is recognized, the large subunit joins to form a complete ribosome. During elongation, aminoacyl‑tRNAs enter the A site, the peptidyl transferase activity of the ribosome catalyses peptide bond formation, and the ribosome translocates along the mRNA; this cycle repeats until a stop codon is encountered. Termination occurs when release factors bind a stop codon, prompting hydrolysis of the peptidyl‑tRNA and disassembly of the ribosomal complex. Translation requires significant energy in the form of GTP and is tightly regulated by initiation and elongation factors. Differences between bacterial and eukaryotic translation make it a target for antibiotics such as tetracycline and chloramphenicol.
Examples of translation in action
Haemoglobin synthesis in developing erythroblasts involves rapid translation of globin mRNAs to match heme availability. Many viruses subvert the host machinery by using internal ribosome entry sites to initiate translation without a 5′ cap; hepatitis C virus is a well‑known example. Some genes employ programmed ribosomal frameshifting or readthrough to produce multiple proteins from a single mRNA, such as the gag‑pol polyprotein of retroviruses. Laboratory antibiotics such as cycloheximide selectively inhibit eukaryotic translation, while puromycin causes premature chain termination. These examples highlight both the versatility of translation and its vulnerability to interference.
Translation is the final step of the central dogma where nucleic acid sequence is converted into functional proteins. Coordinated initiation, elongation and termination ensure fidelity and efficiency, and differences between organisms provide useful targets for therapeutics.
Related Terms: Transcription, mRNA, Ribosome, tRNA, Genetic code