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The last steps of this process occur in mitochondria. The reduced molecules NADH and FADH 2 are generated by the Krebs cycle, glycolysis, and pyruvate processing. These molecules pass electrons to an electron transport chain, which releases the energy of oxygen to create a proton gradient across the inner mitochondrial membrane.
It is an active pump that generates a proton concentration gradient across the inner mitochondrial membrane, because there are more protons outside the matrix than inside. The difference in pH and electric charge (ignoring differences in buffer capacity) creates an electrochemical potential difference that works similar to that of a battery or ...
According to the chemiosmotic coupling hypothesis, proposed by Nobel Prize in Chemistry winner Peter D. Mitchell, the electron transport chain and oxidative phosphorylation are coupled by a proton gradient across the inner mitochondrial membrane. The efflux of protons from the mitochondrial matrix creates an electrochemical gradient (proton ...
The energy transferred by electrons flowing through this electron transport chain is used to transport protons across the inner mitochondrial membrane, in a process called electron transport. This generates potential energy in the form of a pH gradient and the resulting electrical potential across this membrane.
In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement.
ATP synthase lies across a cellular membrane and forms an aperture that protons can cross from areas of high concentration to areas of low concentration, imparting energy for the synthesis of ATP. This electrochemical gradient is generated by the electron transport chain and allows cells to store energy in ATP for later use.
Complex III and IV are proton pumps, pumping H+ protons out of the mitochondrial matrix, and work in conjunction with complex I to create the proton gradient found at the inner membrane. Cytochrome c is and electron carrier protein that travels between complex III and IV, and triggers apoptosis if it leaves the cristae. Complex IV passes ...
This electrochemical gradient creates potential energy (see potential energy § chemical potential energy) across the inner mitochondrial membrane known as the proton-motive force. As a result, chemiosmosis occurs, and the enzyme ATP synthase produces ATP from ADP and a phosphate group.