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94 Cards in this Set
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Bioenergetics |
Quantitative study of the energy transformations in the living cell and the nature and function of the chemical processes underlying these transformations |
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Metabolism |
An intricate network of multienzyme reactions/processes highly coordinated and regulated to meet the needs of the cell |
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Multi-step reaction pathway, Enzyme-catalyzed steps, Central reaction pathways/metabolites, Few types of reactions, Pathways are interrelated, Regulatory mechanisms |
General features of metabolism (6) |
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Catabolism |
The breakdown of larger molecules into smaller ones; oxidative; releases energy |
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Anabolism |
Synthesis of larger molecules from smaller ones; reductive; requires energy |
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Catabolism |
Exergonic, converging |
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Anabolism |
Energonic, diverging |
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Not enzymatically identical, Both pathways occur in 3 major stages, Both pathways are subject to regulation |
3 features of catabolism and anabolism pathways |
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1. Interconversion of polymers and complex lipids with monomeric intermediates 2. Interconversion of monomeric sugars, amino acids, and lipids with still simpler organic compounds 3. Ultimate degradation to or synthesis from inorganic compounds, including CO2, H2O, and NH3 |
Three stages of catabolism and anabolism |
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To provide ATP for energy-dependent activities of the cell, To provide reducing power (NADH, NADPH, etc.), To provide building blocks |
Strategy of metabolism (3) |
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First law of thermodynamics |
Energy can neither be created nor destroyed but can only be transformed from one form to another |
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🔺H = Q - W (Enthalpy = heat absorbed - work done) |
Equation for first law of thermodynamics |
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Second law of thermodynamics |
States that all processes, whether chemical or biological, tend to progress toward a situation of maximum entropy |
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Entropy (S) |
Measure or indicator of the degree of disorder or randomness in a system |
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Equilibrium |
Results when the randomness or disorder is at a maximum |
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Q = T🔺S (Heat = temp x entropy) |
Equation for second law of thermodynamics |
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Gibbs Free Energy |
Unifies the 1st and 2nd law of thermodynamics |
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🔺G |
Value of 🔺G when process is exergonic, favorable/spontaneous |
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🔺G > 0 |
Value of 🔺G when endergonic, not favorable |
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🔺G = 0 |
Value of 🔺G when at equilibrium |
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Kcal, joules |
Unit of energy |
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Concentration of reactants and products |
🔺G is dependent on this factor |
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Standard Free Energy Change, 🔺G^o |
🔺G under standard conditions, that is, when reactants and products are kept at 1M concentrations |
Nitrogenous base + sugar + phosphate group |
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Nucleotide |
Type of molecule of ATP |
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-7300 cal/mol |
🔺G^o of hydrolysis of ATP for each of the 2 terminal PO4 groups |
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Adenosine triphosphate |
High-energy phosphate compounds |
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PEP, 1,3-biphosphoglycerate, Phosphocreatine |
Examples of very high energy phosphate compounds |
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Very high energy phosphate compounds |
Have 🔺G^o of hydrolysis > -10,000 cal/mol |
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Low energy phosphate compounds |
Have a 🔺G^o of hydrolysis |
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Glucose 6-P, Glycerol 3-P, AMP |
Examples of low energy phosphate compounds |
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Electron transport chain |
ETC |
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Respiratory chain |
Other name of ETC |
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Inner mitochondrial membrane |
Location of ETC |
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Electron transport chain |
Final common pathway by which electrons derived from different fuels of the body flow to oxygen |
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5 separate enzyme complexes |
Organization of ETC |
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Complexes I-IV |
Contain part of ETC |
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Complex V |
Catalyzes ATP synthesis |
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Coenzyme Q, Cytochrome C |
Relatively mobile electron carriers (examples) |
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1. Formation of NADH 2. NADH dehydrogenase 3. Coenzyme Q 4. Cytochromes 5. Cytochrome a + a3 6. Inhibitors |
Reactions of the ETC (6) |
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Formation of NADH |
NAD+ is reduced to NADH by dehydrogenases (removes 2 H atoms from their substrate) Both e- but only 1 H+ are transferred to the NAD+ forming NADH + H+ |
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NADH Dehydrogenase |
H+ + H- carried by NADH are next transferred to NADH dehydrogenase |
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NADH Dehydrogenase |
Enzyme complex embedded in inner mitochondrial membrane |
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FMN, Several iron atoms paired with sulfur atoms |
Contents of NADH dehydrogenase |
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FMN |
Accepts 2H atoms, becoming FMNH2 |
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Several iron atoms paired with sulfur atoms |
Necessary for transfer of H atoms to coenzyme Q (ubiquinone) |
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Coenzyme Q |
Can accept H atoms both from FMNH2 (NADH dehydrogenase) and FADH2 (succinate dehydrogenase and acyl CoA dehydrogenase) |
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Cytochromes |
e- are passed down the chain from coenzyme Q to cyt b, c, and a+a3 |
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Cytochromes |
Contains a heme group made of a porphyrin ring containing an atom of iron |
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Cytochrome iron |
Reversibly converted from its ferric to its ferrous form |
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Cyt a+a3 |
Cytochrome oxidase Contains bound copper atoms required for complex reaction |
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Cyt a+a3 |
At this site, the transported e-, molecular oxygen and free protons are brought together to produce water |
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Inhibitors of electron transport |
Prevent the passage of e- by binding to a component of the chain |
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Amytal and rotenone, Antimycin, CN- and CO- |
Examples of inhibitors of electron transport |
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Amytal and rotenone |
Inhibits NADH dehydrogenase |
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Antimycin |
Inhibits cyt b-c complex |
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CN- and CO- |
Inhibits cyt oxidase |
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Cyanide Poisoning |
CN- acts as final e- acceptor; mitochondrial respiration and energy production cease; cell death occurs rapidly |
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Hypoxic injury |
Happens when a tissue is deprived of its oxygen supply as a result of e- transport inhibition; dec ATP; inc anaerobic glycolysis; inc lactic acid; dec pH; damage lysosomal membranes; digestion of cellular components |
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Complex I, NADHQ reductaze |
Other names of NADH dehydrogenase |
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FMN, Fe-S |
Prosthetic groups of NADH dehydrogenase |
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NADH |
E- donor of NADH dehydrogenase |
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CoQ |
E- acceptor of NADH dehydrogenase |
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Rotenone, Riboflavin deficiency |
Inactivated NADH dehydrogenase |
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Coenzyme Q, Ubiquinone |
Other names of CoQ |
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CoQ |
Prosthetic groups of CoQ |
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NADH dehydrogenase |
Electron donor of CoQ |
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b-c1 complex |
E- acceptor of CoQ |
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Generation of free radicals, Doxorubicin |
Inactivates CoQ |
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Complex III, Ubiquinone-cytochrome c oxidoreductase |
Other names of cytochrome b-c1 complex |
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Fe-S, Heme b562, Heme b566, Heme c1 |
Prosthetic groups of cytochrome b-c1 complex |
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CoQ |
E- donor of cytochrome b-c1 complex |
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Cytochrome c |
E- acceptor of cytochrome b-c1 complex |
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Antimycin, Demerol, Fe deficiency |
Inactivates cytochrome b-c1 complex |
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Heme c |
Prosthetic group of cytochrome c |
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Heme c |
Prosthetic group of cytochrome c |
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Cytochrome oxidase |
E- acceptor of cytochrome c |
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Fe deficiency |
Inactivates cytochrome c |
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Complex IV, Cytochrome aa3 |
Other names of cytochrome oxidase |
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Heme a, Heme a3, CuA, CuB |
Prosthetic groups of cytochrome oxidase |
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Cytochrome c |
E- donor of cytochrome oxidase |
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O2 |
E- acceptor of cytochrome oxidase |
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Cyanide, Carbon monoxide, Ischemia, Fe and Cu deficiency |
Inactivates cytochrome oxidase |
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Complex II |
Other name for succinate dehydrogenase |
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FAD, Fe-S |
Prosthetic groups of succinate dehydrogenase |
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Succinate |
E- donor of succinate dehydrogenase |
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CoQ |
E- acceptor of succinate dehydrogenase |
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Malonate |
Inactivate succinate dehydrogenase |
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Standard Reduction Potential, Eo |
Characterized tendency of a redox pair to lose e- |
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Mitchell Hypothesis |
Also known as chemiosmotic hypothesis (oxidative phosphorylation) |
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Mitchell Hypothesis |
Explains how the free energy generated by the transport of e- via ETC is used to produce ATP from ADP and Pi |
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Electron transport |
Accdg to chemiosmotic hypothesis, this is coupled to transport of protons across the inner mitochondrial membrane from the matrix to the intermembrane space |
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Chemiosmotic hypothesis |
Creates an electrical gradient and pH gradient which produces energy sufficient to drive ATP synthesis |
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ATP synthetase (complex V) |
Synthesizes ATP using the energy of the proton gradient generated by ETC; converts ADP and Pi to ATP and H2O |
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Chemiosmotic hypothesis |
Proposes that after protons have been transferred to the cytosolic side of the inner mitochondrial membrane, they can reenter the matrix by passing through a channel in the ATP synthetase molecule resulting in the synthesis of ATP from ADP and Pi and at the same time, dissipating the pH and electrical gradients |
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