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Multiple Choice
Chloroplasts and mitochondria are thought to be of prokaryotic origin. One piece of evidence that supports this hypothesis is that these organelles contain prokaryotic-like ribosomes. These ribosomes are probably most similar to ribosomes found __________.
A
free in the cytoplasm of eukaryotes
B
on the rough ER
C
free in the cytoplasm of eukaryotes and on the rough ER
D
free in the cytoplasm of eukaryotes, on the rough ER, and in bacterial cells
E
in bacterial cells
Verified step by step guidance
1
Understand the endosymbiotic theory, which suggests that chloroplasts and mitochondria originated from prokaryotic cells that were engulfed by ancestral eukaryotic cells.
Recognize that one piece of evidence supporting this theory is the presence of prokaryotic-like ribosomes within chloroplasts and mitochondria.
Recall that prokaryotic ribosomes are smaller (70S) compared to eukaryotic ribosomes (80S), and are similar to those found in bacteria.
Identify that the ribosomes in chloroplasts and mitochondria are most similar to those found in bacterial cells, not those found in the cytoplasm or on the rough ER of eukaryotic cells.
Conclude that the similarity of ribosomes in chloroplasts and mitochondria to bacterial ribosomes supports the hypothesis of their prokaryotic origin.