Electron Transport Chain in Urdu| Biochemistry| ETC| Hira Teaches
Electron Transport Chain in Urdu| Biochemistry| ETC| Hira Teaches Oxidation is defined as the loss of electrons and reduction as the gain in electrons. When a substance exists both in the reduced state and in the oxidized state, the pair is called a redox couple. Biological oxidation: The transfer of electrons from the reduced coenzymes through the respiratory chain to oxygen is known as biological oxidation. The electron transport chain is functioning inside the mitochondria. The mitochondrion is a subcellular organelle having the outer and inner membranes enclosing the matrix. The inner membrane is highly selective in its permeability, containing specific transport proteins. The inner membrane contains the respiratory chain and translocating systems. In the electron transport chain, or respiratory chain, the electrons are transferred from NADH to a chain of electron carriers. The electrons flow from the more electronegative components to the more electropositive components. ii. All the components of electron transport chain (ETC) are located in the inner membrane of mitochondria. iii. There are four distinct multi-protein complexes; these are named as complex-I, II, III and IV. These are connected by two mobile carriers, co-enzyme Q and cytochrome C. Complex V is a protein complex that contains a domain (Fo) that spans the inner mitochondrial membrane, and a domain (F1) that appears as a sphere that protrudes into the mitochondrial matrix. Complex V catalyzes ATP synthesis and so is referred to as ATP synthase. ETC-Complex 1 i. It is also called NADH-CoQ reductase or NADH dehydrogenase complex. It is tightly bound to the inner membrane of mitochondria. ii. It contains a flavoprotein (Fp), consisting of FMN as prosthetic group and an iron-sulphur protein (Fe-S). NADH is the donor of electrons, FMN accepts them and gets reduced to FMNH2. Two electrons and one hydrogen ion are transferred from NADH to the flavin prosthetic group of the enzyme. NADH + H+ + FMN → FMNH2 + NAD+ The electrons from FMNH2 are then transferred to Fe-S. The electrons are then transferred to coenzyme Q (ubiquinone) (CoQ). iv. Overall function of this complex is to collect the pair of electrons from NADH and pass them to CoQ. ETC chain complex II (Succinate-Q-Reductase) CoQ is a mobile carrier and can accept hydrogen atoms both from FMNH2, produced on NADH dehydrogenase (Complex I), and from FADH2, produced on succinate dehydrogenase (Complex II), glycerophosphate This is a cluster of iron-sulphur proteins, cytochrome b and cytochrome c1, both contain heme prosthetic group. The proton pumps (complexes I, III and IV) expel H+ from inside to outside of the inner membrane. So, there is high H+ concentration outside the inner membrane. This causes H+ to enter into mitochondria through the channels (Fo). ATP synthase or complex V: The enzyme complex ATP synthase (Complex V) synthesizes ATP using the energy of the proton gradient generated by the electron transport chain. During this process of transfer of electron, the iron in heme group shuttles between Fe3+ and Fe2+ forms. Complex IV or Cytochrome Oxidase It contains different proteins, including cytochrome a and cytochrome a3. The Complex IV is tightly bound to the mitochondrial membrane. At this site, the transported electrons, O2, and free protons are brought together, and O2 is reduced to water dehydrogenase and acyl CoA dehydrogenase. CoQ transfers electrons to Complex III. CoQ, then, links the flavoproteins to the cytochromes.
Electron Transport Chain in Urdu| Biochemistry| ETC| Hira Teaches Oxidation is defined as the loss of electrons and reduction as the gain in electrons. When a substance exists both in the reduced state and in the oxidized state, the pair is called a redox couple. Biological oxidation: The transfer of electrons from the reduced coenzymes through the respiratory chain to oxygen is known as biological oxidation. The electron transport chain is functioning inside the mitochondria. The mitochondrion is a subcellular organelle having the outer and inner membranes enclosing the matrix. The inner membrane is highly selective in its permeability, containing specific transport proteins. The inner membrane contains the respiratory chain and translocating systems. In the electron transport chain, or respiratory chain, the electrons are transferred from NADH to a chain of electron carriers. The electrons flow from the more electronegative components to the more electropositive components. ii. All the components of electron transport chain (ETC) are located in the inner membrane of mitochondria. iii. There are four distinct multi-protein complexes; these are named as complex-I, II, III and IV. These are connected by two mobile carriers, co-enzyme Q and cytochrome C. Complex V is a protein complex that contains a domain (Fo) that spans the inner mitochondrial membrane, and a domain (F1) that appears as a sphere that protrudes into the mitochondrial matrix. Complex V catalyzes ATP synthesis and so is referred to as ATP synthase. ETC-Complex 1 i. It is also called NADH-CoQ reductase or NADH dehydrogenase complex. It is tightly bound to the inner membrane of mitochondria. ii. It contains a flavoprotein (Fp), consisting of FMN as prosthetic group and an iron-sulphur protein (Fe-S). NADH is the donor of electrons, FMN accepts them and gets reduced to FMNH2. Two electrons and one hydrogen ion are transferred from NADH to the flavin prosthetic group of the enzyme. NADH + H+ + FMN → FMNH2 + NAD+ The electrons from FMNH2 are then transferred to Fe-S. The electrons are then transferred to coenzyme Q (ubiquinone) (CoQ). iv. Overall function of this complex is to collect the pair of electrons from NADH and pass them to CoQ. ETC chain complex II (Succinate-Q-Reductase) CoQ is a mobile carrier and can accept hydrogen atoms both from FMNH2, produced on NADH dehydrogenase (Complex I), and from FADH2, produced on succinate dehydrogenase (Complex II), glycerophosphate This is a cluster of iron-sulphur proteins, cytochrome b and cytochrome c1, both contain heme prosthetic group. The proton pumps (complexes I, III and IV) expel H+ from inside to outside of the inner membrane. So, there is high H+ concentration outside the inner membrane. This causes H+ to enter into mitochondria through the channels (Fo). ATP synthase or complex V: The enzyme complex ATP synthase (Complex V) synthesizes ATP using the energy of the proton gradient generated by the electron transport chain. During this process of transfer of electron, the iron in heme group shuttles between Fe3+ and Fe2+ forms. Complex IV or Cytochrome Oxidase It contains different proteins, including cytochrome a and cytochrome a3. The Complex IV is tightly bound to the mitochondrial membrane. At this site, the transported electrons, O2, and free protons are brought together, and O2 is reduced to water dehydrogenase and acyl CoA dehydrogenase. CoQ transfers electrons to Complex III. CoQ, then, links the flavoproteins to the cytochromes.