(b) The antibiotic streptomycin inhibits protein synthesis in bacteria. If this antibiotic is added to a culture of animal cells
, protein synthesis in the cytosol continues normally. However, over time, the population of mitochondria in the cell becomes depleted. Specifically, it is observed that the protein-synthesis machinery inside the mitochondria is inhibited. Explain this observation based on what you know about the origins of the modern eukaryote.
Mitochondrial ribosomes are similar to the prokaryotic ribosomes since mitochondria evolved by endosymbiosis. So, antibiotics can affect protein synthesis in mitochondria.
Explanation:
Streptomycin is an antibiotic that controls bacterial growth by binding to the small ribosomal subunit (the 30S) of bacteria. Thereby, this antibiotic interferes with protein synthesis and causes misreading of mRNA. Mitochondria were evolved when an anaerobic prokaryote engulfed an aerobic prokaryote which in turn became symbiotic later and lost the ability to live freely.
The ribosomes of mitochondria are similar to the bacterial ribosomes and are inhibited by the presence of streptomycin. Therefore, streptomycin was directly able to inhibit the protein synthesis in mitochondria while not affecting the same process in the cytosol of the cell.
