ribosomene

Ribosomene, commonly referred to as ribosomes, are complex molecular machines that synthesize proteins in cells. They consist of ribosomal RNA (rRNA) and ribosomal proteins assembled into two subunits. In bacteria and archaea, ribosomene are 70S particles composed of a small 30S subunit and a large 50S subunit. In eukaryotes, cytosolic ribosomene are 80S, formed by 40S and 60S subunits. Mitochondria and chloroplasts retain 70S-like ribosomene, reflecting their bacterial origin.

Ribosomene function by decoding messenger RNA (mRNA) to produce a polypeptide chain. The small subunit binds mRNA and ensures correct codon-anticodon pairing with transfer RNAs (tRNAs) in the large subunit, which forms the growing peptide chain through peptidyl transferase activity, primarily carried by rRNA. Translation proceeds in three phases: initiation, elongation, and termination. Initiation requires initiation factors and a start codon; elongation adds amino acids sequentially; termination occurs at stop codons with release factors.

Location varies: cytosolic ribosomene synthesize most cytosolic and nuclear proteins, while ribosomene bound to the rough endoplasmic reticulum synthesize proteins destined for secretion, insertion into membranes, or localization to certain organelles. Ribosome biogenesis occurs in the nucleolus in eukaryotes, where rRNA is transcribed, processed, and assembled with proteins before export to the cytosol.