The Electron Transport Chain

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ETC in: Eukaryotes collection of molecules embedded in the inner membrane of mitochondria Cristae- infoldings of the inner membrane Prokaryotes found in the plasma membrane. Most components are proteins in nature. Multiprotein complexes(1 to 4) Contain prosthetic groups

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During electron transport  electron carriers alternate between reduced and oxidised. Entry of electron in an EC from “uphill” EC reduced Exit of electron from an EC to “downhill” EC oxidised. “Downhill”EC more electronegative than their “uphill” EC.

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NADH from glycolysis and kreb’s cycle transfer electrons to Complex 1. Complex 1 flavoprotein, named after its prosthetic group, flavin mononucleotide(FMN) Flavoprotein oxidises when passing electrons to an iron-sulfur protein (Fe-s in complex 1)

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FADH2 reduced product of Citric acid cycle Transfers electrons to complex 2 Complex 2 lower energy level than complex 1

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Not a protein Small and hydrophobic in nature Individually mobile within the membrane Fe-S group of complex 1 and 2 transfer their electrons to ubiquinone. The latter is reduced while the 2 complexes return back to their oxidized state

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Remaining carriers between ubiquinone and water. Protein in nature Prosthetic group heme ETC has different kinds of cytochromes, different proteins with slightly different heme groups also. cyta3 last cytochrome, gives electrons to final acceptor  Oxygen A pair of hydrogen ions is also picked up for each oxygen atom forming water.

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ATP synthase enzyme that makes ATP from ADP and pi In eukaryotes found embedded in the inner membrane of mitochondria In prokaryotes in plasma membrane ATP synthase makes use of existing ion gradient to fund synthesis of ATP Ion gradient H+ gradient across inner membrane of mitochondrion Chemiosmosis carrying out cellular work using energy stored in the form of H+ ion gradient across a membrane.

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ATP synthase multisubunit complex with four main parts Each part multiple polypeptides H+ ions move one by one into binding sites on one of the parts, resulting in spinning of the rotor in a way to catalyse ATP production

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ETC energy converter

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Makes use of exergonic flow of electrons to pump H+ into intermembrane space. Protons tendency to flow back towards the matrix( down its concentration gradient) The membrane then, offers only one route or exit ATP synthase

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Proton motive force the H+ gradient generated when H+ is pumped into the intermembrane space. Chemiosmosis an energy coupling mechanism that uses energy stored in the form of H+ gradient across a membrane to drive cellular work.