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53 Cards in this Set
- Front
- Back
where is most of the energy of glucose conatined?
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in pyruvate
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4 options of pyruvate
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1) Lactate
2) Acetyl- CoA 3) OAA 4) Alanine |
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where is alanine formed from pyruvate?
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cytosol
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where is lactate formed from pyruvate?
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cytosol
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where is OAA formed from pyurvate?
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mitochondrial matrix
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where is Acetyl-CoA formed from pyruvate?
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mitochondrial matrix
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Which two fates of pyruvate are irreversible?
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OAA and Acetyl-CoA
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what can pyruvate be oxidized to only in microbes?
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acetaldehyde- ethanol.....releases NADH
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Where does the potential engegy of glucose remain?
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in Pyruvate and in the two NADH's from Glyceraldehyde 3-P Dehydrogenase
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What is the factor determining the fate of pyruvate?
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Oxygen availablilty!!!!!!
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2 helpful things that occur when pyruvate-lactate
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1)regenerates NAD+
2) lactate is transported back into the liver to form glucose by gluconeogenesis |
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what converts pyruvate to alanine?
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L-glutatmate (amino group donar)
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What is the fate of pyruvate in gluconeogenesis?
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pyruvate- PEP
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pyruvate- PEP is NOT energetically favorable....two steps required to overcome energy barrier
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1)pyruvate- OAA
2) OAA-PEP |
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What happens to pyruvate when oxygen is plentiful?
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forms Acetyl CoA
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what is one of the most important IRREVERSIBLE steps in metabolism?
WHY? |
Pyruvate- Acetyl CoA
can no longer be used to make glucose |
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is the concentration of Pyruvate or Lactate higher in cell?
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Lactate concentration is MUCH higher
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overall reaction of Alanine Aminotransferase
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Pyruvate + NADH +NH3 = Alanine + NAD+
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what donates amino group to Pyruvate to form Alanin?
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Ll-Glutamate..... gets oxidized to alpha ketoglutarate
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Pyruvate oxidized/or reduced when forms Lactate?
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Reduced because you can see that NADH gets oxidized to NAD+
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what is the additional good thing that occurs due to formation of alanine from pyruvate?
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NH3 (toxic) gets converted into a derrivative that can be safely transported back to the liver
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Enzyme that catalyzes reaction of pyruvate to lactate
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Lactate Dehydrogenase
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Important Points from Lactate Dehydrogenase Reaction
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NAD+ is getting reduced
1) H goes as Hydride (H-) from NADH to C2 of Pyruvate (pyruvate gets reduced) 2) adds to carbonyl group and makes lactate 3)the reaction is STEREOSPECIFIC (which side o NADH ring loses H-) 4)ARGININE and HISTIDINE residues aid in catalysis |
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which aa residues help in catalysis of Lactate Dehydrogenase Rxn?
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ARGININE AND HISTIDINE
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Where is Pyruvate Dehydrogenase Complex located?
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In the mitochondria
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Three protiens that make up the enzyme Pyruvate Dehydrogenase Complex?
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1) Pyruvate Dehydrogenase
2) Dihydrolipoyl Transacetylase 3) Dihydrolipoyl Dehydrogenase |
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cofactor of Pyruvate Dehydrogenase (E1)
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TPP
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cofactor of Dihydrolipoyl Transketolase
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Lipoamide
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cofactor of Dihydrolipoyl Dehydrogenase
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FAD
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vitamin of FAD
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riboflavin
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What is the overall goal of Pyruvate Dehydrogenase Complex?
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To convert Pyruvate to Acetyl CoA
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Pyruvate---> Acetyl CoA + ?
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CO2 (has one less carbon than Pyruvate)
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what is the role of TPP in Pyruvate Dehydrogenase?
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transfers a 2C unit to Lipoamide
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what is released during TPP reaction?
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CO2
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What is the role of Lipoamide?
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Has a long swinging arm that brings the 2C piece to CoA, forming Acetyl CoA
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what hapens to Sulfurs in presence of Lipoamide?
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Disulfur (SH-SH) gets reduced to a dithiol
(S-S). |
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What happens in the Dihydrolipoyl Dehydrogenase reaction?
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Two electrons are taken out...flavin gets reduced....NAD+ gets reduced to NADH....(in order to oxidize dithiol back to disulfide)
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Two ways energy is captured by Pyruvate Dehydrogenase Complex
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!)Acetyl CoA
2) NADH |
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what are inhibitors of the Pyruvate Dehydrogenase Complex?
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Acetyl CoA, NADH AND ATP
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what inactivates the Pyruvate Dehydrogenase Complex? How?
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Pyruvate Dehydrogenase Kinase
Phosphorylation makes it INACTIVE |
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What are things that activate the Pyruvate Dehydrogenase Complex?
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Insulin in adipose tissue....wants to take up glucose and use Acetyl CoA to make fatty acids!!
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What is Beriberi?
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Deficiency in Thiamine
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how is Beriberi measured?
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transketolase
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what are found in very high levels of patients with Beriberi?
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pyruvate and alpha ketoglutarate
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what is sydrome in alcoholics due to thiamine insufficiency?
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Wernike- Korsakoff Syndrome
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what is always the substrate for TPP?
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ketone
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what does TPP transfer?
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activated aldehyde groups
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4 reactions requiring Thiamine
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1) Pyruvate Dehydrogenase Complex
2) Transketolase (PP Pathway) 3) alpha-Ketoglutarate Dehydrogenase (TCA cycle) 4) one more in catablism of aa's |
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What enzyme transforms Pyruvate to OAA?
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Pyruvate Carboxylase (Same as in gluconeogenesis)....ATP is split
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cofactor for Pyruvate Carboxylase?
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biotin
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what does biotin do?
where does it work? |
installs C02 on a molecule
pyruvate +C02 = OAA |
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Pyruvate Decarboxylase requres what cofactor?
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TPP
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How is usage of TPP in Pyruvate Decarboxylase different than usage in Pyruvate Dehydrogenase Complex?
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1) no oxidation/reduction
2) no NAD/NADH part to it 3) no Flavin part |