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28 Cards in this Set
- Front
- Back
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What are the 4 fates of pyruvate?
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1) alanine
2) oxaloacetate 3) acetyl coA 4) Lactate |
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What is the net reaction of the TCA cycle?
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3NAD+ + FAD + GDP + Pi + Acetyl CoA --> 3NADH + FADH2 + GTP + CoA + 2Co2
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How much energy comes from Glycolysis, Pyruvate Dehydrogenase & TCA Cycle?
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-Glycolysis: 2NADH, 2ATP
-Pyruvate Dehydrogenase: NADH (x2) -TCA Cycle: 3NADH, FADH, GTP (x2) |
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Oxidative phsotphorylation takes place in the _______ while the TCA cycle takes place in the _______
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-mitochondrial inner membrane
-mitochondrial matrix |
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Glucose gets converted to _____ which crosses the mitochondrial membrane & ends up in the matrix where the TCA cycle starts
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pyruvate
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What are the three enzymes of the pyruvate dehydrogenase complex?
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-E1: pyruvate dehydrogenase
-E2: Dihydrolipoyl acetyltransferase -E3: Dihydrolipoyl dehydrogenase |
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What are the 5 coenzymes of the pyruvate dehydrogenase complex?
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1) Thiamine Pyrophosphate (derived from Vitamin B1)
2)CoA 3) Lipoate 4) FAD (derived from Vitamin B2) 5)NAD |
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beri-beri disease
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-Deficiency of thiamine (Vitamin B1)
-causes problems with the pyruvate dehydrogenase complex |
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Wernicke-Korsakoff (Wernicke's Encepalopathy)
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-Deficiency of thiamine (Vitamin B1)
-causes problems with the pyruvate dehydrogenase complex |
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How is pyruvate dehydrogenase regulated by phosphorylation? What compounds regulate the kinase & the phosphatase?
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-phosphorylated: INACTIVE, kinase inhibited by substrates, ADP, ATP, activated by products
-dephosphorylated: ACTIVE, phosphatase activated by calcium & insulin |
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What does a high lactate/pyruvate ration indicate a problem in?
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-not being able to do oxidative phosphorylation
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Leigh's disease
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-caused by deficiencies in pyruvate dehydrogenase
-neurological disorder, lactic acidosis -try to treat with high fat diet b/c fat can be converted to acetyl-CoA without pyruvate dehydrogenase |
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What can Acetyl-CoA turn into besides going into TCA (3 things)?
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1) Fatty Acids
2) Cholesterol/steroids 3) Ketone bodies |
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What are the substrates of the TCA cycle?
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-Citrate, Isocitrate, Alpha Ketoglutarate, SuccinylCoA, Succinate, Fumarate, Malate, Oxaloacetate
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What 3 enzymes does arsenate target?
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1) G3P dehydrogenase
2) Pyruvate Dehydrogenase 3) Alpha Ketoglutarate Dehydrogenase |
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What substrate of the TCA can be exported out of the mitochondria & converted back into AcetylCoA to make fatty acids?
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Citrate
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How does the TCA teach us about stereospecificity? (Aconitase or Isocitrate dehydrogenase)
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-molecule going in is not optically active but you end up with optically active product, therefore enzyme creates the stereospecificity
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______, in the TCA cycle, can be converted to Phosphoenolpyruvate
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Oxaloacetate
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______, in the TCA cycle, can be interconverted to glutamate
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Alpha ketoglutarate
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______, in the TCA cycle, is a precursor for heme biosynthesis
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Succinyl-CoA
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______, in the TCA cycle, is exported to the cytoplasm for glucose synthesis
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Maltate
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_______, in the TCA cycle, is formed int he breakdown of tyrosine & urea cycle
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Fumarate
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Oxaloacetate can be formed by __________ from pyruvate
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pyruvate carboxylase
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What are anaplerotic reactions?
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-other reactions which maintain levels of TCA cycle intermediates
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Which intermediate of the TCA cycle is the most important for regulating speed & concentration?
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Oxaloacetate
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What two steps regulate the TCA cycle?
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1) Isocitrate --> alpha ketoglutarate
2) alpha ketoglutarate --> succinyl CoA -both of these steps generate CO2 |
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What are some general inhibitors & activators of the TCA cycle?
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-inhibitors: NADH, ATP, products
-activators: ADP, Calcium, NAD+ |
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How does insulin regulate the TCA cycle?
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-Insulin slows down the cycle so that cycle can back up at Citrate which can leave mitochondria & be converted to Acetyl CoA & then into fat
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