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31 Cards in this Set
- Front
- Back
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In muscles and liver, G1P is used differently. Explain.
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Liver: G1P for maintaining blood sugar.
Muscle: G1P for energy |
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GLUT1-5 are used in which parts of the body and what are their Km's?
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GLUT1 and GLUT3 has Km 1mM and used by neuronal and RBCs.
GLUT2 has Km 15-20mM and used by liver and pancreatic B-Cells GLUT4 has Km 5mM and transports glucose into skeletal muscle and fats. GLUT5 is used by small intestine, mostly for fructose uptake. |
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Where is the only reducing end of a glycogen molecule?
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At the Glycogenin.
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Draw how G6P is imported/exported from liver ER and how glucose is exported to plasma. (p80)
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Draw how G6P is imported/exported from liver ER and how glucose is exported to plasma. (p80)
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p80-1: Note how phosphoylase clips off glucose-1p molecules from glycogen and how it can do it only so far (to last 4su) - debranching enzyme must come in and move 3su to end of longer chain and alpha1-6glucosiade releases that last su as free glucose.
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Note how phosphoylase clips off glucose-1p molecules from glycogen and how it can do it only so far (to last 4su) - debranching enzyme must come in and move 3su to end of longer chain and alpha1-6glucosiade releases that last su as free glucose.
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How/why is UTP used in glycogen synthesis? (p81)
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BC it activates G-1-P. By adding UDP to it, it leaves behind a pyrolphosphate that is instantly degraded to 2P. This drives rxn to right.
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Glycolysis produces ? molecules of ATP and a net gain of ? ATP per glucose catabolized. In addition, each 3-C intermediate is oxidized to form ? NADH, a net gain of ? NADH per glucose metabolized.
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Glycolysis produces 4 molecules of ATP and a net gain of 2 ATP per glucose catabolized. In addition, each 3-C intermediate is oxidized to form 1 NADH, a net gain of 2 NADH per glucose metabolized.
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What are the three irreversible steps/enzymes in glycolysis?
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Hexokinase (some disagree), PFK-1, and Pyruvate Kinase.
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In CHO metabolism, isomerases interconvert what>?
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Aldoses and ketoses.
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What is the most important allosteric activator of PFK-1?
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F-2,6-BP
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Review pg 95: SHowing that F2,6BP increases activity and of PFK-1. Even if ATP is around, if F2,6BP is around, PFK-1 is active. If F2,6BP is not around and ATP is, PFK-1 is quickly inactivated.
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Review pg 95: SHowing that F2,6BP increases activity and of PFK-1. Even if ATP is around, if F2,6BP is around, PFK-1 is active. If F2,6BP is not around and ATP is, PFK-1 is quickly inactivated.
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Can you guess - is liver Pyruvate kinase activate or deactivated by cAMP dependent kinase phosphorylation? Why?
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Deactivated. When cAMP levels are high, glucose is low, so you want to prevent glycolysis so that the liver can send it out to circulation. Thus you want to turn off Pyruvate kinase.
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Why is NAD important for glycolysis?
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It cannot continue without it.
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Make sure you understand what's going on on pg 103. Ie, in liver, what happens happens with high insulin vs glucagon?
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Insulin = stimulation of glycolysis (i.e. you want to get rid of high glucose)
Glucagon = inhibits glycolysis (ie you want glucose to enter cells). |
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p105-6: review how Pyruvate is converted back to PEP for the purposes of gluconeogenesis. This can be accomplished in two ways: via malate or aspartate
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p105-6: review how Pyruvate is converted back to PEP for the purposes of gluconeogenesis. This can be accomplished in two ways: via malate or aspartate
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For the purposes of gluconeogensis, what is the enzyme that is opposite to PFK-1?
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Fructose-1,6-Bisphosphatase.
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What is the NADPH/NADP ratio?
What is the NADH/NAD+ ratio? What does this indicate? |
70:1 vs 1:700 respectively. It indicates the the cell has a lot of reducing potential whereas NADH ratio indicates that the cells do not store much energy as NADH.
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How does the cell combat oxidative stress? What role does NADPH play?
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Combats it with GSH. When GSH attacks an oxygen radical, it is oxidized to GSSG. To reduce it back, NADPH is used.
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Transketolase transfers how many C's and requires what co-factor. Transaldolase transfers how many C's?
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Transketolase transfers 2-C and requires Thiamine Diphosphate.
Transaldolase transfers 3-Cs. |
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Glucose-6-phosphate dehydrogenase deficiency is the most common enzyme abnormality in the world. What does this cause? It usually goes undiagnosed until what happens? Examples include?
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Hemolytic anemia - bc it results in a deficiency in NADPH and thus an increase in oxidative stress. It's X-linked so it mainly affects males. Goes undiagnosed until pt undergoes significant oxidative stress as in administration of oxidant drugs (AAA = antibiotics, antimalarials, and Antipyretics.)
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General rxn by which CH4 is converted to CO2 to release energy? See pg 123
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General rxn by which CH4 is converted to CO2 to release energy? See pg 123
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What is the enzyme that links glycolysis to TCA cycle? (p127)
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Pyruvate dehydrogenase complex.
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The PDH complex requires a vitamin - what is it? What part of the complex is it involved with? Why is it important?
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Thiamine. It is E1 of the complex. If not available, there's no way to connect glycolysis to the TCA cycle. Causes bBeriberi.
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Where does the TCA cycle take place? All of the enzymes are free floating except?
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Mitochrondrion. Succinate dehydrogenase is the only one bound to the mitochondrial matrix.
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What are the principle regulatory signals for the TCA cycle?
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ATP, ADP, NAD+ and NADH. Succinyl-CoA also serves as a regulator.
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What is thought to be the key regulated step in TCA cycle? What is it activated and inhibited by?
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Isocitrate dehydrogenase. Inhibited by ATP and NADH; activated by ADP and AMP.
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What is one of the rxns used to replenish the TCA cycle intermediates? (the major one he talked about?)
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Pyruvate carboxylase. It essentially is on all the time to make Oxaloacetate. If it makes it unecessarily, it is converted to Malate or Aspartate, shunted out of the matrix, and converted to fat.
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Mitochondria in State 3 are:
Mitochondria in State 4 are: |
3: Working
4: Resting |
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Cyanide, Carbon monoxide and Nitric oxide block what complex(es) in ETC? What does NO block at high concentrations?
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They all block Complex 4 and at high NO concentrations, it blocks I and II.
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How many electrons do Pyridines carry? Flavins? Fe centers and cytochromes?
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Pyridines = 2
Flavins = 1 or 2 Fe Centers/Cytochromes = 1 |
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Remember this: Acetaldehyde is higher on the table than NADH is so it's favorable rxn. Ethanol is lower on the table than NADH so the rxn is not favorable. Pos = favorable. Neg = unfavorable.
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Remember this: Acetaldehyde is higher on the table than NADH is so it's favorable rxn. Ethanol is lower on the table than NADH so the rxn is not favorable. Pos = favorable. Neg = unfavorable.
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