Q.(a) Explain the reactions taking place in mitochondrial inner membrane. OR

Cytochromes are the electron-carrier proteins of the mitochondrial electron transport system (ETS).

During aerobic respiration, NADH and FADH2 generated in glycolysis, the link reaction, and the Krebs cycle are oxidised in the inner mitochondrial membrane by the electron transport system. This system is made up of a series of electron carriers, chiefly the cytochromes (haem-containing proteins such as cytochrome b, c1, c, a, a3) along with other complexes, which pass electrons from one to the next in a stepwise, energy-releasing manner, ultimately reducing molecular oxygen to water while pumping protons that drive ATP synthesis (oxidative phosphorylation, chemiosmosis).

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ETS is short for Electron Transport System, the chain of carrier complexes on the inner mitochondrial membrane responsible for oxidative phosphorylation.

During aerobic respiration, the reduced coenzymes NADH and FADH2 generated in glycolysis and the Krebs cycle carry high-energy electrons to a series of membrane-embedded protein complexes located on the cristae of the mitochondrion. These complexes — Complex I through Complex IV, along with mobile carriers like ubiquinone and cytochrome c — together constitute the Electron Transport System (ETS). As electrons pass along this chain, protons are pumped acro …

Oxygen is the terminal electron acceptor of the mitochondrial electron transport chain in aerobic respiration.

During aerobic respiration, electrons released from NADH and FADH2 (generated in glycolysis, the link reaction, and the Krebs cycle) are passed sequentially through a series of electron carriers/complexes (including cytochromes) embedded in the inner mitochondrial membrane — this is the electron transport chain (ETC). As electrons move through the chain, protons are pumped across the membrane, creating a gradient used by ATP synthase to make ATP (oxidative phosphorylation). At the very end of the chain, the electrons (along with H+ ions) are accepted by molecular oxygen (O2), which is reduced to form water (H2O). Because oxygen is the la …

Oxygen (O2) is the final electron acceptor of the electron transport chain in aerobic respiration.

During aerobic respiration, NADH and FADH2 (generated in glycolysis, the link reaction, and the Krebs cycle) donate electrons to a series of carriers (Complexes I-IV) in the electron transport chain (ETC) located on the inner mitochondrial membrane. As electrons pass down this chain, energy is released and used to pump protons, ultimately driving ATP synthesis by chemiosmosis (oxidative phosphorylation). At the very end of the chain, the electrons (together with protons) are accepted by …

Cytochrome c is the mobile electron carrier of the electron transport chain, since unlike the other cytochromes it is not fixed within a membrane complex.

The electron transport chain (ETC), located on the inner mitochondrial membrane, consists of a series of large, membrane-embedded protein complexes: NADH dehydrogenase (Complex I), succinate dehydrogenase (Complex II), the cytochrome bc1 complex containing cytochromes b and c1 (Complex III), and cytochrome c oxidase containing cytochromes a and a3 (Complex IV).

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The electron transport chain (Complexes I-IV and ATP synthase) is located in the inner mitochondrial membrane.

The mitochondrion has two membranes: a smooth outer membrane and a highly folded inner membrane (folds called cristae). The inner membrane houses the protein complexes of the electron transport system (Complex I: NADH dehydrogenase, Complex II: succinate dehydrogenase, Complex III: cytochrome bc1, Complex IV: cytochrome c oxidase) along with ATP synthase (Complex V). Electrons from NADH and FADH2 (produced in glycolysis, pyruvate oxidation, and the Krebs cycle occurring in the mitochondrial matrix) are passed along these complexes in the inner membrane, pumping protons into the intermembrane space and creating a proton gradient that drives ATP synthesis via chemiosmosis (oxi …