| Criteria | Mitochondrial Ribosome (Mitoribosome) | Cytoplasmic Ribosome (Animal Cell) | Remarks |
| Location | Located within the mitochondrial matrix | Found in the cytoplasm and on rough endoplasmic reticulum (RER) | Compartmentalized based on functional roles in distinct organelles |
| Origin | Derived from bacterial ancestors (α-proteobacteria-like) | Eukaryotic origin, evolved from ancient ribosomes | Reflects endosymbiotic theory and distinct evolutionary paths |
| Size (Svedberg Units) | ~55S–60S (in mammals, e.g., 28S + 39S subunits) | 80S (composed of 40S small and 60S large subunits) | Mitoribosomes are smaller and more protein-rich than cytoplasmic ribosomes |
| rRNA to Protein Ratio | Lower rRNA content; higher protein content (~25:75) | Higher rRNA content; lower protein content (~60:40) | Inverse composition in terms of protein and RNA content |
| Function | Synthesizes mitochondrial-encoded proteins essential for oxidative phosphorylation | Synthesizes majority of cellular proteins encoded by nuclear DNA | Both ribosomes perform translation but on different transcript sources |
| Genetic Code Usage | Uses a slightly modified genetic code | Uses the universal genetic code | Variations include different codon interpretations (e.g., UGA codes for Trp in mitochondria) |
| Antibiotic Sensitivity | Sensitive to some prokaryotic antibiotics (e.g., chloramphenicol) | Sensitive to eukaryotic translation inhibitors (e.g., cycloheximide) | Reflects structural similarity of mitoribosomes to bacterial ribosomes |
