pH intermembrane space pH matrix final destination under aerobic conditions multi subunit complex of proteins Series of electron carriers in membranes o Occurs in cytoplasmic membrane in Prokaryotes and inner mitochondrial membrane in Eukaryotes o Cristae folds increase SA to allow for increased number of unique ETC to produce the max amount of ATP Complex I o Receives 2 e from NADH and releases NAD and H into the matrix NADH becomes oxidized and is recycled in the cell o Harnesses energy from the 2 e to pump protons from the matrix into the intermembrane space o Ubiquinone mobile carrier takes 2 e from final member of Complex I U becomes reduced floats through fluid lipid bilayer where it drops off the 2 e to the first member of Complex III U becomes oxidized Complex III o Harnesses energy from the 2 e to pump protons from the matrix into the intermembrane space o Cytochrome C mobile carrier takes 2 e from final member of Complex III Cyt C becomes reduced floats through fluid lipid bilayer where it drops off the 2 e to the first member of Complex IV Cyt C becomes oxidized Complex IV o Harnesses energy from the 2 e to pump protons from the matrix into the intermembrane space o The final electron acceptor is oxygen o Oxygen accepts 2 e from Complex IV and combines with 2 H that are found in the matrix forming water Oxygen which is then free to cross the membrane it is small and nonpolar is found in the matrix 2 H from the matrix combined with 2 e from Complex IV form 2 H atoms of O2 2H H2O Complex II o Receives 2 e from FADH2 and releases FAD and H FADH2 becomes oxidized and recycled in the cell o o o Does NOT harness energy from the 2 e to pump protons from the matrix into the intermembrane space Ubiquinone mobile carrier takes 2 e from Complex II U becomes reduced floats through fluid lipid bilayer where it drops off the 2 e to the first member of Complex III U becomes oxidized Receives 2 e from FADH2 and releases 2 H into the matrix Path of electrons from NADH Complex I Complex III Complex IV O 2 Path of electrons from FADH2 Complex II Complex III Complex IV O 2 there is less of an electrochemical gradient formed from FADH 2 compared to NADH because it bypasses Complex I Electrons carried by Ubiquinone from either Complex I or II to Complex III and electrons are carried by Cytochrome C from Complex III to Complex IV Energy from e is NOT sufficient to phosphorylate an ADP into an ATP but it will create and electrochemical gradient by the pumping of protons from the matrix into the intermembrane space creating an electrochemical gradient Each e carrier is at a lower energy level as the one before it The final product is water a very low energy molecule 10x inc in H compared to matrix 10x inc in H compared to matrix 10x increase in H from intermembrane space compared to matrix The protons from the intermembrane space can freely transport into the cytoplasm via porins o This relationship keeps the pH of the intermembrane space and the cytoplasm the same ATP Synthase ETC carries e ATP Synthase carries H ATP Synthase is NOT part of the ETC it is a separate entity that generates ATP Net yield of ATP from o NADH 3 ATP o FADH2 2 ATP Substrate level phosphorylation the energy comes from a coupled exergonic reaction o This can occur in the cytoplasm glycolysis or the mitochondrial matrix Krebs cycle Oxidative phosphorylation chemiosmosis the energy comes from the flow of H through an ATP Synthase channel o This occurs in the inner mitochondrial membrane this concept can be compared to a dam where the water is comparable to the H ions ATP Synthase is a small channel that allows H from the intermembrane space back into the matrix o This transforms the kinetic energy into mechanical energy turning a rotor that will expose the enzyme s active site favoring this reaction ADP Pi ATP Overall Only 2 ATP from each NADH because it costs 1 ATP to transport each NADH into the mitochondria All types of food sources can be incorporated into this pathway
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