Large-scale example model of oxidative ATP synthesis

4 Large-scale example model of oxidative ATP synthesis 

The mitochondrion is the key cellular organelle responsible for transducing free energy from primary substrates into the ATP potential that drives the majority of energy-consuming processes in a cell. Thus the mitochondrion plays a central 

Matrix. This large internal space contains a highly concentrated mixture of hundreds of enzymes, including those required for the oxidation of pyruvate and fatty acids for the citric acid cycle. The matrix also contains several identical copies of the mitochondrial DNA genome, special mitochondrial ribosomes, tRNAs, and various enzymes required for expression of mitochondrial genes. 

Inner membrane. The inner membrane is folded into numerous cristae, greatly increasing its total surface area. It contains proteins with three types of functions (1) those that carry out the oxidation reactions of the electron transport chain, (2) the ATP synthase that makes ATP in the matrix, and (3) transport proteins that allow the passage of metabolites into and out of the matrix. An electrochemical gradient of H+, which drives the ATP synthase, is established across this membrane, so the membrane must be impermeable to ions and most small charged molecules. 

Outer membrane. Because it contains a large channel-forming protein (called porin), the outer membrane is permeable to all molecules 5000 daltons or less. Other proteins in this membrane include enzymes involved in mitochondrial lipid synthesis and enzymes that convert lipid substrates into forms that are subsequently metabolized in the matrix. 

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