Complexes of ETC, their composition and flow of electrons through the complexes

Complexes of ETC, their composition and flow of electrons through the complexes
Flow of Electrons through the Complexes
Proton Pumping
ATP Synthesis Complexes of the
Electron Transport Chain (ETC)Biochemistry Biology Electron Transport Chain And their Structures

1. Biochem-51 2 BIOENERGETICS Laiba (2022-uam-5027)

2. Complexes of ETC, their composition and flow of electrons through the complexes

3. T he ETC is a complex system that relies on the coordinated effort of multiple protein complexes, electron carriers, and enzymes to generate energy for the cell. Objective:

4. Transport Chain (ETC) is a series of protein complexes located in the mitochondrial inner membrane. It plays a crucial role in cellular respiration, generating most of the energy that cells need to function. The ETC consists of four main complexes, each with a unique composition and function. Complexes of the Electron Transport Chain ( ETC) Complex I (NADH Dehydrogenase ) Complex II (Succinate Dehydrogenase ) Complex III (Cytochrome b-c1 Complex ) Complex IV (Cytochrome Oxidase)

5. Complex I (NADH Dehydrogenase): Composed of 45 subunits, Complex I is the largest complex in the ETC. It receives electrons from NADH and passes them to Coenzyme Q ( CoQ ). Composition : 45 subunits, including FMN and iron-sulfur clusters. Function: Receives electrons from NADH and passes them to Coenzyme Q ( CoQ ). Electron transfer: NADH → FMN → Iron-sulfur clusters → CoQ . 2. Complex II (Succinate Dehydrogenase): Composed of 4 subunits, Complex II is also known as Succinate Dehydrogenase. It receives electrons from succinate and passes them to CoQ Composition : 4 subunits, including FAD and iron-sulfur clusters. Function: Receives electrons from succinate and passes them to CoQ . Electron transfer: Succinate → FAD → Iron-sulfur clusters → CoQ .

6. 4. Complex IV (Cytochrome Oxidase): Composed of 13 subunits, Complex IV receives electrons from Cytochrome c and passes them to oxygen, resulting in the formation of water. 3. Complex III (Cytochrome b-c1 Complex): Composed of 11 subunits, Complex III receives electrons from CoQ and passes them to Cytochrome c. Composition: 11 subunits, including hemes and iron-sulfur clusters. Function : Receives electrons from CoQ and passes them to Cytochrome c. Electron transfer: CoQ → Cytochrome b → Cytochrome c1 → Cytochrome c. Composition: 13 subunits, including hemes and copper centers. Function : Receives electrons from Cytochrome c and passes them to oxygen, resulting in the formation of water. Electron transfer: Cytochrome c → Cytochrome a → Oxygen → Water.

7. Electrons from NADH: Electrons from NADH are passed to Complex I, which then passes them to CoQ . Electrons from Succinate : Electrons from succinate are passed to Complex II, which then passes them to CoQ . Electrons from CoQ : Electrons from CoQ are passed to Complex III, which then passes them to Cytochrome c. Electrons from Cytochrome c: Electrons from Cytochrome c are passed to Complex IV, which then passes them to oxygen, resulting in the formation of water. Flow of Electrons through the Complexes :

8. Coenzyme Q ( CoQ ): An electron carrier that plays a central role in the ETC. Cytochrome c : An electron carrier that transfers electrons from Complex III to Complex IV. ATP synthase: An enzyme that generates ATP from the proton gradient established by the ETC. Other Components During the flow of electrons through the complexes, protons (H+ ions) are pumped across the mitochondrial inner membrane, creating a proton gradient. This gradient is used to drive the production of ATP through the process of chemiosmosis. Proton Pumping: ATP Synthesis : The energy generated from the proton gradient is used to drive the production of ATP through the process of chemiosmosis. This process involves the movement of protons back across the mitochondrial inner membrane, driving the production of ATP through the enzyme ATP synthase.

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