The ribosomes in eukaryotic cells are larger than the ribosomes in prokaryotic cells. Furthermore, eukaryotic ribosomes are not affected by some chemicals that affect prokaryotic ribosomes, a fact that can be put to good use by microbiologists seeking new antimicrobial drugs. An example of this is the antibiotic erythromycin, which prevents protein synthesis by prokaryotic ribosomes but does not affect eukaryotic ribosomes at all. Thus, erythromycin kills bacteria but does not affect humans or other animals. Using this information, which of the following would be expected and would support the endosymbiont hypothesis?
A) Mitochondrial ribosomes will be smaller than prokaryotic ribosomes.
B) Mitochondria and chloroplasts will not have ribosomes.
C) Mitochondrial ribosomes will be larger than prokaryotic ribosomes.
D) The ribosomes in chloroplasts will be sensitive to erythromycin.

Question

Quizplus · Accepted Answer

The endosymbiont hypothesis suggests that mitochondria and chloroplasts originated from prokaryotic cells that were engulfed by an ancestral eukaryotic cell. Therefore, if chloroplast ribosomes are sensitive to erythromycin, similar to prokaryotic ribosomes, it supports the idea that chloroplasts have a prokaryotic origin.

The Ribosomes in Eukaryotic Cells Are Larger Than the Ribosomes