Practice question

Prokaryotic ribosome sediments at 70S, consisting of small 30S subunit with 16S rRNA and 21 proteins and large 50S subunit with 23S plus 5S rRNAs and 33 proteins. S values are not additive because shape influences hydrodynamic behavior. 70S ribosome decodes bacterial mRNAs containing Shine-Dalgarno sequences, sensitive to antibiotics like chloramphenicol and tetracycline targeting bacterial-specific features. Cytosolic eukaryotic ribosome is larger at 80S, while mammalian mitochondrial ribosome is 55S, illustrating evolutionary divergence from bacterial ancestor despite shared ancestry. This refined regulation supports accurate ribosomal assembly, quality control and translational fidelity under diverse physiological conditions and growth states.