A central tenet in mitochondrial bioenergetics is that exergonic electron transfer drives the creation of an electrical potential () across the inner mitochondrial membrane (IMM). This is entirely true. Another tenet of mitochondrial bioenergetics, that you will read everywhere, is that this electrical potential is created by three proton pumps, Complexes I, III and IV. This is less true. A proton pump is this: It’s a protein that binds a proton from one side of a membrane, translocates that very proton across the membrane, through the protein, and ejects it into solution on the other side of the membrane. Complex I is a proton pump, but we did not discuss complex I. Complex III is NOT a proton pump, yet it creates electrical potential across the IMM. It is an electron/proton charge separation device. Complex IV is both types of these devices. Fifty percent of the electrical potential that complex IV creates is as a proton pump. But, 50% of the electrical potential that complex IV creates is as an electron/proton charge separation device. Using a generalized terminology (i.e. neither CIII nor CIV specific), explain how a electron/proton charge separation device, ala CIII and CIV, generate
Electron Transport Chain
The electron transport chain, also known as the electron transport system, is a group of proteins that transfer electrons through a membrane within mitochondria to create a gradient of protons that drives adenosine triphosphate (ATP)synthesis. The cell uses ATP as an energy source for metabolic processes and cellular functions. ETC involves series of reactions that convert redox energy from NADH (nicotinamide adenine dinucleotide (NAD) + hydrogen (H)) and FADH2(flavin adenine dinucleotide (FAD)) oxidation into proton-motive force(PMF), which is then used to synthesize ATP through conformational changes in the ATP synthase complex, a process known as oxidative phosphorylation.
Metabolism
Picture a campfire. It keeps the body warm on a cold night and provides light. To ensure that the fire keeps burning, fuel needs to be added(pieces of wood in this case). When a small piece is added, the fire burns bright for a bit and then dies down unless more wood is added. But, if too many pieces are placed at a time, the fire escalates and burns for a longer time, without actually burning away all the pieces that have been added. Many of them, especially the larger chunks or damp pieces, remain unburnt.
Cellular Respiration
Cellular respiration is the cellular process involved in the generation of adenosine triphosphate (ATP) molecules from the organic nutritional source obtained from the diet. It is a universal process observed in all types of life forms. The glucose (chemical formula C6H12O6) molecules are the preferred raw material for cell respiration as it possesses a simple structure and is highly efficient in nature.
A central tenet in mitochondrial bioenergetics is that exergonic electron transfer drives the creation of an electrical potential () across the inner mitochondrial membrane (IMM). This is entirely true. Another tenet of mitochondrial bioenergetics, that you will read everywhere, is that this electrical potential is created by three proton pumps, Complexes I, III and IV. This is less true. A proton pump is this: It’s a protein that binds a proton from one side of a membrane, translocates that very proton across the membrane, through the protein, and ejects it into solution on the other side of the membrane. Complex I is a proton pump, but we did not discuss complex I. Complex III is NOT a proton pump, yet it creates electrical potential across the IMM. It is an electron/proton charge separation device. Complex IV is both types of these devices. Fifty percent of the electrical potential that complex IV creates is as a proton pump. But, 50% of the electrical potential that complex IV creates is as an electron/proton charge separation device. Using a generalized terminology (i.e. neither CIII nor CIV specific), explain how a electron/proton charge separation device, ala CIII and CIV, generate
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