The theory of endosymbiosis

Endo means within and symbiosis is where two or more organisms live together to help support their life functions. This theory suggests that some kind of larger cell would have engulfed smaller cells by endocytosis and then not digested or later let them go. We know of many cells whose functions is to engulf material, an example is the white blood cells in our immune system. They also reproduce in a binary fission manner similar to prokaryotes and have different genetic material to the nuclear DNA of the cells they are found in.

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