Support for the endosymbiotic hypothesis is provided by all of the following except
A) double membranes around mitochondria and chloroplasts.
B) mitochondria and chloroplasts have their own genomes.
C) mitochondria and chloroplasts can synthesize proteins.
D) mitochondria and chloroplast ribosomes are encoded by genes that are very similar to bacterial ribosome genes.
E) mitochondria and chloroplasts contribute to different metabolic processes in the eukaryotic cell.

Question

Quizplus · Accepted Answer

If certain bacteria were engulfed by primitive and eukaryotic cells and not digested, then they would acquire an extra membrane outside the original bacterial plasma membrane; this would explain the double membrane structure of mitochondria and chloroplasts. Since bacteria have their own genetic material, mitochondria and chloroplasts would be expected, as descendants of free-living bacteria, to have their own DNA and ribosomes. Thus, mitochondria and chloroplasts can carry out their own protein synthesis. The fact that mitochondria and chloroplasts contribute to different metabolic processes (aerobic respiration and photosynthesis) in the cell does not provide direct support for the endosymbiotic hypothesis. However, it does make sense in light of the likely origins of these two organelles: The mitochondria are descendants of aerobic bacteria and the chloroplasts are descendants of cyanobacteria.

Support for the Endosymbiotic Hypothesis Is Provided by All of the Following