Oxidative Phosphorylation and Glucose Metabolism Flashcards
What are the purposes of catabolic pathways
Breakdown of larger molecules into smaller building units. Release and (temporary) storage of energy in high-energy molecules through ATPS/NTPs and Reduced cofactors (NADH/FADH2)
How are catabolic pathways oxidative
Metabolites are oxidized as cofactors are reduced. Re-oxidization of cofactors is used to generate ATP.
What is the overview of Oxidative Phosphorylation
Reduced cofactors (NADH, FADH2) from glycolysis and CAC (oxidative catabolism). Which leads to electron transport chain (reoxidation of NADH/FADH2) (reduction of O2 to H2O). Which leads to proton gradient (inner mitochondrial membrane). Which leads to ATP synthesis.
Where does Oxidative Phosphorylation occur
Inner mitochondria membrane
What are the components of the electron transport chain
Complexes 1-4
Coenzyme Q
Cytochrome C
What are the cofactors in oxidative phosphorylation
Flavin mononucleotide (Prosthetic groups), Iron-sulfur clusters (Prosthetic groups), Copper (Cu2+) (Prosthetic groups), Cytochrome heme groups (Prosthetic groups), Coenzyme Q (Lipid-soluble cofactor). Each cofactor has a characteristic reduction potential or affinity for electrons. Electrons move from cofactors will lower reduction potential to those with higher reduction potentials.
What are cytochromes
Cytochromes are hemoproteins that carry out electron transport.
What is Coenzyme Q
Lipid-soluble molecule. It transports electrons to Complex 3 from Complexes 1 and 2 in the inner mitochondrial membrane (Cosubstrate for all three complexes).
What is the Electron Transport Chain
Redox reactions have a free energy change related to reduction potential. Reduction potential is “affinity for electrons.” Higher reduction potential leads to a more negative free energy. Electrons move from compounds with lower reduction potentials to those with higher reduction potentials. Free energy changes from redox reactions can be used to transport protons across the membrane (primary active transport)
What is the number of protons reoxidized by every NADH
Every NADH reoxidized results in 10 protons being move out of the matrix
What is the number of protons reoxidized by every FADH2
Every FADH2 reoxidized results in 6 protons being moved out of the matrix
What is the overall potential energy converted to
Overall, the potential energy of the H+ gradient is converted to the chemical energy in the phosphoanhydride bonds of ATP.
What is FO of ATP Synthase
FO: Oligomycin. Transmembrane portion, Protons pass through and Triggers conformational change in F1.
What is F1 of ATP Synthase
Catalytic portion and Synthesis of ATP from ADP and Pi.
What is the adenine nucleotide translocase and the Pi H+ support
Newly synthesized ATP is export from the mitochondrial matrix into the cytosol where it can be used to “drive” the many energy-requiring processes in the cell. The ADP and Pi produced in the cytosol are then transported back into the mitochondrial matrix.
What is the P:O Ratio
P:O Ratio is the amount of ATP made (P) per oxygen atom reduced to water (O): 1 water made for each NADH or FADH2 reoxidized (each 2 electrons)
Non-stoichiometric: P:O ratio is ~2.5 ATP/NADH reoxidized, P:O ration is ~1.5 ATP/FADH2 reoxidized
P:O ratio may vary with uncoupling.
What is the rate of oxidative phosphorylation determined by
O2 consumption (via electron transport) is connected to ATP production at the ATP Synthase. Oxygen consumption increases when ADP concentration rises. ADP concentration reflects the energy-consumption of the cell.
What is the coupling of ATP synthesis to electron transport
Oxygen consumption increases in isolated mitochondria when ATP synthesis is stimulated (addition of ADP)
What does oxygen consumption increase
The presence of an uncoupler. This refers to situations when electron transport occurs without ATP synthesis (and thus, also, when catabolism of fuel molecules occurs without ATP synthesis). The proton gradient is then dissipated faster, and the rate of electron transport increases (O2 consumption goes up). The rate of re-oxidation of reduced electron carriers increases, and the rate of reactions in the citric acid cycle increases.
What is the uncoupling of ATP synthesis to electron transport
Oxygen consumption with uncouplers, even in the absence of ATP synthesis.
What is Complex 2
Succinate Dehydrogenase (part of the citric acid cycle). An integral membrane protein, Complex II contains FAD as a prosthetic group. Catalyzes oxidation of succinate to fumarate as part of the citric acid cycle. Electrons from succinate are ultimately transferred to coenzyme Q in the membrane. No protons are moved across the membrane at Complex II
What do uncoupled systems allow
Uncoupled systems allow protons to enter the matrix without ATP synthesis. Protons may enter matrix through a separate process, generating heat instead of ATP
How does oxygen consumption increase in the presence of an uncoupler.
This refers to situations when electron transport
occurs without ATP synthesis (and thus, also, when
catabolism of fuel molecules occurs without ATP
synthesis). The proton gradient is then dissipated faster, and the rate of electron transport increases (O2 consumption goes up). The rate of re-oxidation of reduced electron carriers increases, and the rate of reactions in the citric acid cycle increases.
How does affect uncoupling of ATP synthesis to electron
Oxygen consumption with uncouplers, even in the absence of ATP synthesis
