Biology as Poetry: Bioenergetics

Bacteriophage Ecology Group

Chemiosmosis

Generation of ATP using the energy associated with proton motive force.

Where osmosis is the movement of water down its concentration gradient, chemiosmosis is the movement of a chemical other than water. Specifically this is ions moving down their concentration gradient across a semipermeable membrane. In the case of ATP generation, this movement powers an enzyme, ATP synthase, which phosphorylates ADP to produce ATP. The proton motive force, in turn, is generated via proton pumping by electron transport chains.

Chemiosmosis is key to the generation of ATP by mitochondria, chloroplasts, and in fact all prokaryotes that employ electron transport chains. Indeed, chemiosmosis, via the proton motive force, couples together all other aspects of cellular respiration with the ATP generation of the ATP synthase step.

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