Practice question

Eukaryotic cytosolic ribosome has sedimentation value 80S, larger than prokaryotic 70S due to expansion segments and additional proteins. It dissociates into 40S small subunit containing 18S rRNA and approximately 33 proteins and 60S large subunit containing 28S, 5.8S and 5S rRNAs with about 49 proteins. Requires higher Mg2+ for subunit association, lower elongation rate, inhibited by cycloheximide rather than bacterial antibiotics. Mitochondrial and chloroplast ribosomes retain bacterial-like 55S and 70S features, respectively, reflecting endosymbiotic origin and specialized translation systems. This refined regulation supports accurate ribosomal assembly, quality control and translational fidelity under diverse physiological conditions and growth states.