Quiz 1-1/25/18 0 points) The antibiotic streptomycin inhibits protein synthesis
ID: 194988 • Letter: Q
Question
Quiz 1-1/25/18 0 points) 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. A. Explain this observation based on what you know about the origins of the modern eukaryote. What do you expect to observe if, in a new experiment, animal cells are treated with diphtheria toxin, a compound that is known to block cytosolic protein synthesis but does not have any impact on bacterial growth'? B. nd faExplanation / Answer
According to the endosymbiotic theory, eukaryotes have evolved by the symbiosis of prokaryotic cells which ultimately lost their autonomy and turned into cell organelles such as mitochondria and chloroplasts.
Pieces of evidence that support the endosymbiotic theory:
a. Both chloroplasts and mitochondria have their own circular genomes
b. They have 70S ribosomes.
Streptomycin is an inhibitor of translation by 70S ribosomes. Since mitochondria also contain 70S ribosomes, they also get adversely affected by Streptomycin. Since some of the mitochondrial proteins are not produced due to protein inhibition in the mitochondria, the number of mitochondria in these cells gets depleted.
Diphtheria toxin is an ADP-ribosyltransferase that inhibits eukaryotic translation process (protein synthesis). So, it will not show any effect on mitochondrial protein translation and survival (ignoring the dependence on cytosolic proteins).
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