Do Eukaryotes or Prokaryotes have 80S ribosomes?

Do Eukaryotes or Prokaryotes have 80S ribosomes?

• A. Eukaryotes
• B. Prokaryotes
• C. Both
• D. Neither

Answer: (A)

Ribosome size in terms of sedimentation rate distinguishes the two groups. The cytoplasmic ribosomes in eukaryotic cells are 80S, built from a 60S large subunit and a 40S small subunit. Prokaryotic cells use 70S ribosomes, composed of a 50S large subunit and a 30S small subunit. The 80S versus 70S difference reflects distinct RNA and protein compositions, which is why many antibiotics target bacterial (70S) ribosomes without affecting eukaryotic (80S) cytoplasmic ribosomes. Note that in eukaryotic organelles like mitochondria and chloroplasts, ribosomes are 70S, reflecting their bacterial origin, but the cytoplasmic translation machinery remains 80S. Thus, eukaryotes have 80S ribosomes.

Ribosome size in terms of sedimentation rate distinguishes the two groups. The cytoplasmic ribosomes in eukaryotic cells are 80S, built from a 60S large subunit and a 40S small subunit. Prokaryotic cells use 70S ribosomes, composed of a 50S large subunit and a 30S small subunit. The 80S versus 70S difference reflects distinct RNA and protein compositions, which is why many antibiotics target bacterial (70S) ribosomes without affecting eukaryotic (80S) cytoplasmic ribosomes. Note that in eukaryotic organelles like mitochondria and chloroplasts, ribosomes are 70S, reflecting their bacterial origin, but the cytoplasmic translation machinery remains 80S. Thus, eukaryotes have 80S ribosomes.