Question

The structure and function of mitochondria are often used as support for the endosymbiotic theory. Describe two of these properties and explain how they support the theory.

Answer 1

First of all the endosymbiotic theory is basically the theory that mitochondria used to be free living bacteria and were taken up by a host cell.

Evidence.......

Structure:
1. Porins (transport proteins) are found in the outer membrane of mitochondria. They are also found in bacterial cell membranes.
2. Cardiolipin is found in mitochondrial and bacterial cell membranes.
3. Mitochondria have circular DNA, which is different from nucleus DNA. However, bacteria also have this feature.
4. Mitochondrial ribosomes are similar to those found in bacteria

Function:
1. Mitochondria are formed only through binary fission, which is how bacterial cells are formed.
2.Mitochondria convert energy into usable forms for the cell through cellular respiration.Therefore, by taking up mitochondria, energy production for the cell would increase significantly.

Why do these add up to a beneficial relationship for both parties?
The host cell was probably anaerobic, which means it can't use oxygen. This also means it is much less efficient than a aerobic cell, meaning there would be partially digested food in it's cytoplasm. The ingested bacteria which would become a mitochondria was aerobic, so it could use oxygen. The aerobic bacterium was able to digest all the partially digested food molecules with oxygen. Through this process, the aerobic bacteria gained great amounts of energy, and ATP most likely leaked over to the host cell. This benefited the anaerobic cell because it was now able to breathe aerobically which means more potential for energy gain.

Hope I helped!