According to the theory of endosymbiosis, describe how mitochondria came to exist within our modern-day eukaryotic cells.

The endosymbiotic theory explains that mitochondria and chloroplasts descended from the same type of bacteria. Symbiosis is an interaction between two organisms of different species, and endosymbiosis is a type of symbiosis in which one organism lives inside the other one. According to the endosymbiotic theory, a host cell ingested symbiotic bacteria, which specialized into mitochondria or chloroplasts. The evidence for this theory is that mitochondria and chloroplasts, like bacteria, have their own circular DNA. They also have their own transcriptional and translational machinery.

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.