Bioenergetics, molecular-level process

Figure 1. Simplified overview of major, molecular-level processes involved in bioenergetics. Reaction centers store light energy by reducing cofactors and bacteriorhodopsin converts light to a proton gmdient. Eventiially, concentration gradients and ATP provide biochemically useful energy.

The study of bioenergetics involves the study of (1) the processes by which reduced nicotinamide and flavin nucleotides, generated primarily from the oxidation of carbohydrates (Chap. 11) and lipids (Chap. 13), are oxidized ultimately by molecular oxygen via the mitochondrial electron-transport chain, and (2) the mechanism by which this oxidation is coupled to ATP synthesis. The synthesis of ATP in this way is referred to as oxidative phosphorylation, in contrast to phosphorylation of ADP via soluble enzymes. The latter involves intermediate phosphate derivatives of the substrate and is known as substrate-level phosphorylation (Chap. 11). 

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