| S.N. | Characteristics | 70S Ribosomes | 80S Ribosomes |
| 1. | Occurrence | They occur in prokaryotic cells and in the mitochondria and plastids of eukaryotic cells. | They occur only in the cytoplasm of eukaryotic cells. |
| 2. | Size | They are smaller in size, measuring 200-300 A0 x 170-210 A0 | They are larger in size, measuring 300-350 A0 x 200-240 A0 |
| 3. | Weight | Lighter (2.7-3.0 million Daltons) | Heavier (4.0-4.5 million Daltons) |
| 4. | Location in the cell | They exist freely in cytoplasmic matrix, mitochondrial matrix and plastid stroma. | They exist freely in cytoplasmic matrix and are also attached to endoplasmic reticulum and outer surface of nuclear envelope. |
| 5. | Synthesis | They are synthesized in the cytoplasm. | They are synthesized in the nucleolus. |
| 6. | Subunits | Two subunits present: Larger 50S and smaller 30S. | Two subunits: Larger 60S and smaller 40S. |
| 7. | Sedimentation coefficient or Svedberg coefficient | 70 | 80 |
| 8. | Number of rRNA molecules | Larger (50S) subunit has two rRNAs (23S and 5S rRNAs) whereas smaller (30S) subunit has only one rRNA (16s rRNA). | Larger (60S) subunit has three rRNAs ( 28S, 5.8S and 5S rRNAs) whereas smaller (40S) subunit has only one rRNA (18S rRNA). |
| 9. | Number of proteins | 55 different basic protein molecules (34 in larger subunit and 21 in smaller subunit) | 78 different basic protein molecules (45 in larger subunit and 33 in smaller subunit). |
| 10. | RNA : Protein ratio | 3:2 or 2:1 (more RNA) | 1:1 (Equal amount of RNA and protein) |
| 11. | Number of amino acids | Around 8,000 | Around 16,000 |
| 12. | Effect of antibiotics on protein synthesis | Protein synthesis is inhibited by antibiotics. | Protein synthesis is not inhibited by antibiotics. |