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health advisory Hospital Doctor Yu 2007-11-8 19:09:36

I am working on A&P 202 and can't find this specific answer.

Answers:

Allowed a cellular organism to produce more energy. More energy was needed for multi-cellular life.

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The Krebs cycle refers to the electron transfer that occurs during photosynthesis. Without this cycle, plants would be unable to capture energy from the sun, storing it as food that can be used by organisms further up the food change.

All living things rely on the sun to provide energy. The Krebs cycle is the mechanism by which that energy becomes available for living things that cannot photosynthesize.

In other words, if there were no Krebs cycle, there would be no life.

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The Krebs Cycle (notice no apostrophe), named after Sir Hans Krebs, outlines the production of NADH from the conversion of pyruvate to carbon dioxide. It is important that the metabolism is localized in the mitochondria. The mitochondria are self-replicating organelles within the cell. (They carry their own DNA.) This means that each cell can use this organelle to produce energy and not require that the cell membrane be involved in the metabolism of energy molecules and the membranes can be more specialized. More specialized membranes means more specialized cells, thus, leading to different tissues. It is the differentiation of tissues that leads to more complex multicellular organisms. (evolution).

It is, also, important that the metabolism is in a cycle that does not consume its intermediate substrates. At the end of the cycle (no end), the system is not exhausted. (as opposed to a fire that just oxidizes and is exhausted) It is a controlled cycle that only consumes substrate and produces energy at a controlled pace.

Aside: I went to Doctor Krebs last lecture two weeks before he died. He was a guest lecture at the University of Miami, School of Medicine in 1981. He was seriously demented by then, but he was a regular doctor before he became a Biochemist. I hope someday to be as great, even if I do become demented.

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Basically, it produces some ATP and NADH. This is critical because these are forms of stored energy which cells need in order to complete synthesis of macromolecules and power protiens.

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