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190 Cards in this Set
- Front
- Back
________ is the simplest unit to enter glycolysis?
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glucose
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_________ from phospho______ can also me metaolized.
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glycerol, phoshphoglycerides
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Galactose enters the glycolysis cycle at?
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Glucose 1 phoshpate (G1P)
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Mannose becomes __________ and enters glycolysis at?
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Mannnose-6-phosphate and enters at Fructose-6-phosphate
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Fructose can enter glycolysis at the _______ stage or can be processed in the liver and enter as glyceraldehyde into ______?
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F6P, Glyceraldehyde3phosphate
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How does glycogen become glucose 1-phosphate?
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the 1>4 glycosidic bond is broken y phosphorolysis. Pi attacks to create G 1-P
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How does Gluc 1-P become Gluc 6-P?
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catalyzed by phosphoglucomutase
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Dextrin + nH2O -----------> n D-Glc
Maltose + H20 -------------> 2 D-Glc Lactose + H2O -------------> D-Gal & D-Glc Sucrose + H2O --------------> D-Fru & D-Glc Trehalose + H20 --------------> 2 D-Glc |
dextrinase
maltase lactase sucrase trehalase |
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In muscles and kidney, fructose is phosphorylated to ___________ by ___________ .
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Fru 6-phosphate by hexokinase
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In the liver, fructose uses the above two step orcess for entry into glycolysis?
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Fructose -----fructokinase----> Fru-1-Phosphate -----fructose 1-phosphate adolase----> Dihydroxyacetone Phosphate -------triose phosphate isomerase----> Gleceraldehyde ----triose kinase----> G 3-P
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Galactose in the diet mainly comes from ________?
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lactose ---> glucose + galactose
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Define the epimerization of glactose to glucose?
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THERE'S MORE TO GROWTH ON GLUCOSE THAN JUST MAKING ATP.....
The net reaction for the oxidation of glucose to ethanol via glycolysis: |
glucose + 2Pi + 2ADP ------> 2ETOH + 2ATP + 2CO2 + 2H2O
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Draw the pentose phosphate pathway starting with glucose 6 phosphate?
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Important products of pentose phosphate pathway include:
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pentososes to make RNA, DNA, coenzymes
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What are the two phases of the pentose phosphate pathway?
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Oxidative phase, used to make pentose phosphates
Nonoxidative phase recycles 6 pentoses (Rn5-P) back to 6 hexoses (G 6-P) |
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oxidoreductases?
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transfer of electrons (hydride ions of H atoms)
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transferases?
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group transfer reactions
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hydrolases?
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hydrolysis reactions, transfer of functional groups to water
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Lyases?
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addition of groups to double bonds or formation of double bonds by reoval of groups
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isomerases?
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transfer of groups within molecule to yield isomeric forms
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ligases
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formation of c-c, c-s, c-s , c-n bonds by condensation reactions coupled to cleavage of ATP or other triphosphates
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Name 6 amino acids that can enter the CA cycle as pyruvate?
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alanine, cysteine, glycine, serine, threonine, tryptophan
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Name the five amino acids that can enter the CA cycle as alpha-ketoglutarate?
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arginine, glutamate, glutamine, histidine, proline
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Name the four aa that can enter the CA cycle as succiny-CoA?
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isoleucine, methionine, threonine, valine
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Name the two aa acids that can enter the CA cycle as fumarate?
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Phenylalanine, tyrosine
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Name the to aa that can enter the CA cycle as Oxaloacetate?
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Asparagine, aspartate
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Name the three irreversible reactions in glycolysis that need to be bypassed in gluconeogensis?
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hexokinase glucose-->Glc6Phos
phosphofructokinase Fru6phos---->Fru1,6Bisphos pyruvate kinase PEP-->pyruvate |
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Name the two enzymes necessary to convert pyruvate back to PEP?
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1. pyruvate caboxylase
2. PEP caboxykinase |
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What are the cofactors for pyruvate carboxlase and what is the product from pyruvate?
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ATP, and biotin
create oxaloacetate but needs a bicarbonate |
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What is the cofactor for PEP caboxykinase and what is the reactant and product?
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GTP is cofactor
reactant is oxaloacetate product is PEP |
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What is the bypass step 2 in gluconeogenesis?
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Fru1,6bisphos ---> Fru6Phos
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What is the enzyme that catalyzes the bypass for step 2 in gluconeogenesis? what is the cofactor?
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Fructose 1,6 bisphosphatase
this rxn requires Mg2+ |
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What is the bypass step 3 in gluconeogenesis?
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Glc6phos--->glucose
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What is the enzyme required in step 3 bypass in gluconeogenesis?
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glucose 6 phophatase
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homeostasis?
regulation? |
maintenance of stable conditions in a metabolically dynamic system
maintains homeostasis |
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Normal Blood glucose levels?
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5mM
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control?
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alters output over time
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futile cycle? aka substrate cycle?
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the uneconomical process of forward and reverse reaction occurring simultaneously at a high rate in the same cell
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Glucogenic?
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"carbon source" that enters into metabolism at a more reduced state than Acetyl-CoA and is capable of producing glucose
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Glucogenesis metabolic cost?
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Requires 6 high energy phosphate groups and 2 NADH to turn 2 pyruvates into 1 glucose
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GLUT2?
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glucose transporter in hepatocytes
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Low ATP =
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High AMP
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acetylCoA =
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citrate
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LIver cell name?
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hepatocyte
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Muscle cell name?
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myocyte
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Liver vs. Muscle
hexokinase Km? responds to? High glucose = ? Low glucose = ? |
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Glucagon _______ blood glucose levels while insulin ________ blood glucose levels.
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increases, decreases
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What is the Core Cycle?
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anaerobic exercise in muscles
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what happens in the liver during the Cori cycle?
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what happens in the muscle during the Cori cycle?
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Enzymes for glycogen breakdown?
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glycogen phosphorylase
glycogen--->Glc1Phos Phosphoglucomutase Glc1Phos--->Glc6Phos |
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What is glycogenin?
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an enzyme involved in converting glucose to glycogen. acting only as a primer connecting the first few glucose molecules until UDP-glucose takes over
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What is the enzyme for extending glycogen?
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UDP-glucose
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Allosteric modulators of PEP/pyruvate interconversions?
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Allosteric modulators of hexokinase?
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draw the pathway for Fru into Gycolysis?
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notice that it become Fru1phos and not Fru6phos
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Draw the pathway for galactose to enter into glycolysis?
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Alternate uses for G6P?
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glycogen, pentose phosphates--->nucleotides
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Alternate uses for F6P?
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amino sugars---->gycolipids and glycoproteins
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Alternate uses for DHAP or G3P?
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Lipids
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Alternate uses for 3PG
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produce serine
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Alternate uses for PEP?
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Aromatic aa
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Alternate uses for pyruvate?
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Aspartate---->pyrimidines or asparagine
alanine |
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Where does the CA cycle occur?
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in the mitochondrial matrix
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What is the product from the pyruvate caboxylase enzyme?
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oxaloacetate
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What cofactors are required by pyruvate carboxylase for conversion to oxaloaetate?
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ATP, bicarbonate, biotynyl enzyme
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Pyruvate and CO2 create ________?
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oxaloacetate
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In the pyruvate dehygrogenase complex what 2 molecules are required for creation of ATP?
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oxaoacetate and __________ form citrate?
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acetyl CoA
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Acetyl CoA and ________ form citrate?
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oxaloacetate
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Aconitase is what kind of enzyme?
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isomerase
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What is the mechanism for isocitrate dehydrogenase?
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Beta-hydroxy decarboxylation
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What mechanism is similar to alpha-ketoglutarate dehydrogenase?
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pryuvate dehydrogenase
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Which residue is responsible for the cleavage of the thioester bond in Succinyl-CoA synthetase?
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histidine
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What drives the malate dehydrogenase reaction?
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low oxaloacetate
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Using delta G "not prime" values _____% of the energy released from the oidation of glucose to CO2 is captured,
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34
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Using just delta G values ____% of the energy released from the oidation of glucose to CO2 is captured,
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65
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Where does the pyruvate carboxylase reaction happen?
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liver, kidney
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Where does the PEP carboxykinase reaction happen?
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heart, muscle
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What are some other roles for:
citrate? alpha-ketoglutarate? succinyl CoA? oxaloacetate? |
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In the Glyoxylate cycle, bypassing the CO2 producing steps allows bacteria and pats to grow on __________?
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acetate
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what 2 enzymes exist in the glyoxylate cycle that don't exist in the CA cycle? What molecule exists in the glyoxylate cycle that doesn't exist in the CA cycle?
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What are the three steps where the CA cycle is regulated?
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citrate synthase
isocitrate DH alpha-ketoglutarate DH |
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What are the positive and negative effectors for the three CA regulation points?
citrate synthase isocitrate DH alpha-ketoglutarate DH |
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___________ are the energetic fatty acid molecule.
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triacylglycerols
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Triacylglycerols are _______ to free _______?
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hydrolyzed, fatty acids and glycerol
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Triacylglycerols are hydrolyzed to free fatty acids and glycerol by _________ and _______?
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lipoprotein lipase, hormone-sensitive triacylglycerol lipase
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Where does glycerol that is released from triacylglycerols get transported to?
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liver or kidney
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What does a freed glycerol get converted to?
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DHAP
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Fatty acid transports into the inner mitochondrial matrix by?
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carnitine palmitoyl transferase
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Beta oxidation of fatty acids produce _______ and ________?
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1 NADH and 1 FADH2
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Beta oxidation of fatty acids information.
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Getting fructose into glycolysis
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The epimerization of galactose to glucose
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The net reaction for the oxidation of glucose to ethanol via glycolysis:
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Glucose + 2 Pi + 2 ADP --->
2 ethanol + 2 ATP + 2 CO2 + 2H20 |
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the pentose phosphate pathway
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What two aa are not gluceogenic aa?
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lysine, leucine
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What are glucogenic aa?
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A glucogenic amino acid is an amino acid that can be converted into glucose through gluconeogenesis.[1][2] This is in contrast to the ketogenic amino acids, which are converted into ketone bodies.
The production of glucose from glucogenic amino acids involves these amino acids' being converted to alpha keto acids and then to glucose, with both processes occurring in the liver. This mechanism predominates during catabolysis, rising as fasting and starvation increase in severity. |
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What are ketogenic aa?
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A ketogenic amino acid is an amino acid that can be degraded directly into Acetyl CoA through ketogenesis
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What are the 7 ketogenic aa?
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leucine
lysine In humans, five amino acids are both ketogenic and glucogenic: isoleucine phenylalanine tryptophan tyrosine threonine |
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Pyruvate carboxylase is a 2-step reaction:
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Bicarbonate is first activated by transient phosphorylation and transfer to biotin
Biotin is a carrier of activated HCO3- Pyruvate enolate attacks CO2 in second step |
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Pyruvate Carboxylase is a _____________: oxaloacetate is shuttled out of mitochondria as _________?
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mitochondrial enzyme, malate
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PEP carboxykinase mechanism?
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Glucose 6 phosphatase is found in ______ ?
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This enzyme is found in the lumen of the endoplasmic reticulum (ER)
Membrane associated, found only in liver/kidney Glucose generated in those tissues is sent to the blood stream to supply brain and muscle |
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Futile cycling with Hexokinase/Glucokinase is limited by multiple regulatory controls?
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Glucokinase has high KM for glucose
Glucokinase activity is inhibited by multiple allosteric regulators Glucokinase is sent to the nucleus during gluconeogenesis |
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Fates of Glucose 6-phosphate formed by glycogen breakdown?
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In muscle, glucose 6-P enters glycolysis
Support muscle contraction In liver, glucose 6-P -> glucose, then released to blood to “buffer” glucose levels |
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Elongation of an existing glycogen chain happens with (enzyme name)?
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glycogen synthase
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Sugar nucleotides are used for?
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Used for polymerizations
Modifications of sugars Nucleotidyl group serves as a handle for enzymes, an excellent leaving group, and a way to set aside sugars for biosynthesis |
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How to make a glycogen particle de nuovo…
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what molecules are needed to create and start glycogen?
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Regulation of glucose metabolism
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Metabolic regulation vs. metabolic control
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Regulation: processes that serve to maintain homeostasis
• Efforts to maintain something steady, even as other things change – Control: processes that lead to a change in the output of a metabolic pathway over time • The change in output is in response to an environmental change |
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Muscle (myotic) and liver (hepatic) during high blood glucose?
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High blood glucose
Muscles synthesize glycogen, increase glucose uptake Liver cells decrease glucose export, increase glycogen synth. & glycolysis |
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Muscle (myotic) and liver (hepatic) during low blood glucose?
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Low blood glucose
Muscles access glycogen, retool metabolism to access other energy sources Liver cells break down glycogen and increase gluconeogenesis to buffer [glucose] in blood |
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These are?
Epinephrine (fight or flight) Ca2+, AMP (rising levels indicate muscle contraction and ATP depletion, respectively) |
reasons to push the CA cycle
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Muscle glycogen phosphorylase is regulated by phosphorylation
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Glycogen phosphorylase of liver cells also serve as a direct sensor of [glucose]
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PP1 ________ which inactivates ___________ signalling the need for less glucose and not to breakdown glycogen.
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dephosphorylates, phosphorylase a making phosphorylase b
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Glycogen Synthase Regulation
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How GSK3 is regulated by Insulin
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General result of PP1 activity is to promote?
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glycogen synthesis
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• Epinepherine & Glucagon inhibit ______ activiity?
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PP!
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Hexokinase is inhibited by____ in myocytes?
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G6P
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Just check this out!!!!!
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Regulator of PFK 1
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ATP decreases, F2,6P is an importat positive activator
PEP and citrate and glucagon inhibit |
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Glucagon causes an _________ in blood glucose levels, while insulin causes a _________ in blood glucose levels,
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increase, decrease
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Regulation of pyruvate kinase
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[F26BP] is controlled by glucagon and insulin
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Differential regulation of carbohydrate metabolism in muscle and liver
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Pyruvate Dehydrogenase Complex enzymes needed?
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Three kinds of enzymes with catalytic cofactors
Thiamine pyrophosphate (TPP) Lipoamide FAD CoA and NAD+ are stoichiometric cofactors |
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Summary of reactions for pyruvate dehydrogenase complex
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Malate is oxidized to form oxaloacetate
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This reaction is driven to the right in the cell due to the low concentration of oxaloacetate (<10-6 M). OAA is rapidly removed by the exergonic rxn of citrate synthase.
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Biosynthetic roles of the citric acid cycle---
Amino acids are derived from citric acid cycle intermediates these are called anaplerotic reactions. oxaloacetate => asp, asn α-ketoglut => glu, gln, pro, arg Succ. CoA => porphyrins |
oxaloacetate => asp, asn
α-ketoglut => glu, gln, pro, arg Succ. CoA => porphyrins |
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Anaplerotic reactions are driven by hydrolysis of a high energy _______ compound or via energetically favorable ________ reactions.
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phosphoryl, redox
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What is an anaplerotic reaction?
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Anaplerotic reactions (from the Greek Ana= 'up' and Plerotikos= 'to fill') are those that form intermediates of a metabolic pathway. Examples of such are found in the Tricarboxylic acid (TCA) Cycle
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Making acetyl CoA from Acetate
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Catalyzed by acetyl CoA synthetase
Acetate + CoA + ATP => acetyl CoA + AMP + PPi PPi (pyrophosphate) is hydrolyzed to orthophosphate Two high-energy phosphoanhydride bonds are used to “activate” acetate |
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Name the molecule that regulates Isocitrate DH?
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Reversible phosphorylation of IDH inhibits enzyme activity (one Pi added per subunit)
Prevents isocitrate binding, no activity |
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Regulation of the Pyruvate Dehydrogenase Complex
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Regulation of Citrate Synthase
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What happens when there’s lots of ATP and Acetyl CoA?
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Use Acetyl CoA to make fatty acids
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_________and _______ are indicators of the energy charge of the cell.
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ATP and NADH
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Regulation of Isocitrate Dehydrogenase
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Regulation of α-ketoglutarate Dehydrogenase
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Regulated in response to energy charge of the cell and accumulation of products
ATP is an allosteric inhibitor High NADH and succinyl CoA levels inhibit |
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Citrate and acetyl CoA feed back to glycolysis
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Excess citrate, inhibit PFK-1 to slow glycolysis
Excess acetyl CoA, inhibit pyruvate kinase to slow pyruvate production |
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Phospholipids are degraded by pancreatic _______________?
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phospholipase A2
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Lipid digestion products are converted to triacylglyerols in the intestinal mucosa and are packaged as lipo-protein complexes (_________) and released into the bloodstream
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chlyomicrons
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Triacylglycerols in chylomicrons and VLDL are hydrolyzed to free fatty acids and glycerol in capillaries of adipose and muscle tissues by ____________?
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lipoprotein lipase
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Triacylglycerols stored in adipose are hydrolyzed to glycerol and free fatty acids by hormone-sensitive ______________?
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triacylglycerol lipase
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Free fatty acids in bloodstream bind to __________ , effectively increasing the ______ of fatty acids many times and preventing their acting as detergents
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serum albumin, solubility
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Glycerol released by hydrolysis of triacylglycerols is transported to liver or kidneys and converted to _______.
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DHAP
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the Activation of Fatty Acids for Oxidation is catalyzed by?
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Activation process is catalyzed by a family of acyl-CoA synthetases
Enzymes differ by their chain-length specificities. These enzymes are associated with either the ER or the outer mitochondrial membrane Catalyze the reaction: FA + CoA + ATP <=> acyl-CoA + AMP + PPi |
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Transport of long-chain fatty acyl-CoA across the mitochondrial inner membrane
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Fatty acids are dismembered through the β oxidation of fatty acyl-CoA, a four reaction process:
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Each round of β oxidation of fatty acids produces one _____, one ______ , and one ______________.
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NADH, FADH2, acetyl-CoA
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Fatty acid synthesis begins with _________ in the cytoplasm?
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malonyl CoA
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Oxidation of odd-chain fatty acids
Some plants and marine organisms make fatty acids with odd number of carbons |
Final round of β oxidation forms propionyl-CoA
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Enoyl coA enzymes do what?
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place the double bonds in the right position for Beta oxidation of fatty acids
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The presence of a double bond at an even numbered carbon atom results in the formation of 2,4-dienoyl-CoA, which is a poor substrate for enoyl-CoA hydratase
The solution is to reduce the double bond at C4, and isomerize (in mammals) to create the appropriate substrate for the hydratase |
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Acetyl-CoA can be made into “ketone bodies”
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Fatty acid synthesis uses ________ as an electron ________?
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NADPH, donor
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Fatty acid Beta Oxidation uses ______ and ______ as electron _________?
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FAD, NAD, electron acceptors
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What are the four major enzymes for FA biosynthesis?
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KS, KR, DH, ER
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Substrate sources for FA biosynthesis
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Their is nor storage of amino acids, they are used for sythesis of _________, and other _________. The rest are used as ________ fuel.
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proteins, biomolecules, metabolic fuel
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Amino Acid Catabolism
Aminotransferases move amino groups from the amino acids to __________. The α-ketoglutarate is converted to _______. The amino acid that donated the amino group is known as an ________? Glutamate is deaminated (oxidatively), then the ______ is excreted in various forms? In mammals, NH4+ is further metabolized to ______ via reactions of the “_____ cycle". |
alpha-ketoglutarate
glutamate α-keto acid NH4+ urea |
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How is this transamination accomplished?
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Mechanism of transamination reactions
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The transamination is only half done after the PLP reaction. Leaving PMP and Alpha-Keto acid.
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PLP catalyzes many reactions of amino acids
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Oxidative deamination of glutamate: catalyzed by glutamate dehydrogenase
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Regulation of glutamate dehydrogenase
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The sum of the reactions catalyzed by aminotransferases and glutamate dehydrogenase
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Glucogenic amino acids contribute carbon skeletons that can lead to formation of _______.
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glucose
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Ketogenic amino acids form “________” (acetone, acetoacetate or hydroxybutarate).
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ketone bodies
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Getting rid of ammonia...
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Transporting excess ammonia to the liver NH4+ is too dangerous to float through the bloodstream to the liver (hepatic cells) where it is formed into urea. In some tissues it ususally combines with _________ and gets transported.
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glutamate
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NH4+ can complex with _____ in urine in kidney during periods of acidosis
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acids
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NH4+ enters urea cycle in _________?
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liver
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________ is used to move “NH4+” from muscle to liver.
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Alanine
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Using glutamate, what two enzymes take alpha-ketoglutarate to glutamate to glutamine?
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Converting NH4+ to Urea: The Urea Cycle
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The reactions of the urea cycle take place in both the ____________________.
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cytoplasm and mitochondria
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Urea comes from ________. Hence, the cycle is designed to regenerate __________.
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arginine
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Making urea from arginine.
arginine amd urea make __________? |
ornithine
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ornithine + _________ ------> citrulline
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carbamoyl phosphate
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carbamoyl phosphate is where we rid ourselves of ________ that is generated by the oxidative deamination of _________, this process costs _____ ATP and occurs in the __________.
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NH4+, glutamate, 2, mitochondria
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The overall stoichiometry of urea synthesis
|
CO2 + NH4+ + 3 ATP + aspartate + 2 H2O ==>
urea + 2 ADP +2 Pi + AMP + PPi +fumarate Pyrophosphate is rapidly hydrolyzed, so 4 ~P are consumed Two are consumed in synthesis of carbamoyl phosphate Two are consumed in synthesis of arginosuccinate Fumarate (oxaloacetate) has several possible fates: transamination to aspartate (take part in urea cycle) conversion to glucose (via PEP and gluconeogenesis) cycling through the citric acid cycle conversion to pyruvate |
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Draw the PLP?
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Draw the PMP?
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