Question

Describe three properties of mitochondria and chloroplasts that support the endosymbiotic theory. Be sure to explain your answer.

Answer 1

endosymbiotic theory: mitochondria and chloroplasts result from prokaryotic pre-forms being absorbed by eukaryotic cells and used as factories to maintain the energy generation.

1.: they have a double membrane. this might look trivial, but if you "eat" a prokaryotic organism, you will enwrap it into your own membrane, resulting in a double membrane.

2.: both of them got their own genetic material, which gets replicated independent from the cell cycle (part of the cell cycle: mit/chl are distributed into the daughter cells). some mit/chl genes are encoded directly there, and some others in the nucleus.

3.: they got their own ribosomes. this is strong evidence that they are former prokaryotic cells, since the ribosomes are 70S grand (svedberg - in a centrifugation, they will appear above eukaryotic ribosomes, that are 80S big). since prokaryotic cells usually got 70S ribosomes and eukaryotic cells got 80S ribosomes, this suggests an endosymbiotic history.

Answer 2

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