How do ribosomes make proteins?
Ribosomes convert information in messenger RNA into an amino acid sequence during translation. They are not made solely of protein: ribosomal RNA plays a central catalytic role.
Codons and transfer RNA
Messenger RNA is read in three-nucleotide codons. Transfer RNAs carrying amino acids pair with codons through their anticodons. Ribosomes catalyze peptide bond formation and move along the RNA. Initiation, elongation, and termination require additional factors. A stop codon recruits termination machinery rather than supplying another amino acid.
From synthesis to a functional protein
The new chain must fold and may require cleavage or chemical modification before functioning. Free and endoplasmic-reticulum-bound ribosomes help produce proteins for different destinations. Several ribosomes can translate one RNA simultaneously, forming a polysome. Protein abundance depends not merely on a gene's presence, but also on RNA production and degradation, translational regulation, and protein lifetime.