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24 Cards in this Set
- Front
- Back
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What does Beta oxidation of FA do?
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Catabolism of FA to form Acetyl CoA-->TCA or ETC
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Where does beta oxidation of FA occur?
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In mitochondrial matrix
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What are the steps of Beta Oxidation?
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1. Activation
2. Carnitine cycle 3. Dehydrogenation 4. Hydration 5. Dehydrogenation 6. Cleavage Repeat |
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Sources of free FA
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1. Dietary fat
2. Stored fat (TAG)-released by lipase 3. Phospholipids |
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Activation of free FA occurs where?
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-Occurs in the outer mitochondrial membrane
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Activation
Fatty acid + ATP-->Fatty acid-CoA |
Fatty acyl-CoA Synthetase
cleavage of PPi-->2Pi makes rxn irreversible |
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Carnitine acyl transferase I (CAT I, regulated)
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-Found on outer mitochondrial membrane
-Fatty-acyl CoA + carnitine --> CoA + fatty acid-carnitine |
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Carnitine acyl transferase II (Cat II, unregulated)
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-Found on inner mitochondiral membrane
-Fatty acid-carnitine + CoA --> carnitine + fatty acyl CoA |
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1. Acyl-CoA --> Enoyl-CoA
alkane --> alkene |
Acyl-CoA dehydrogenase
FADH2 Dehydrogenation (oxidation) |
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2. Enoyl-CoA + H2O -->B-hydoxyacyl CoA
Double bond --> Alcohol |
Enoyl CoA hydratase
Hydration |
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3. B-hydroxyacyl-CoA --> B-ketoacyl-CoA
Alcohol --> ketone |
B-hydroxyacyl-CoA dehydrogenase
NADH |
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4. B-ketoacyle CoA --> acetyl CoA
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B-keto thiolase
Cleavage |
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Enoly CoA isomerase
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-Unsaturation in wrong place and/or wrong configuration
-for odd number |
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Reductase and enoyl CoA isomease
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-Removes an additional double bond and transfers another to the right place
-even numbered |
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Odd number of carbons in acyl chain
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6 acetyl CoA + 1 propionyl CoA (3C)
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Regulation of B-oxidation when starvation
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free FA levels increases bc of lipases which are stimulated by epinephrine and glucagon
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Regulation of B-oxidation when well fed
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FA decrease due to inhibition of adipose cell lipase by insulin
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Regulation of CAT I
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Inhibited by high concentrations of malonyl CoA
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Inhibition of B-hydroxyacyl CoA dehydrogenase by?
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NADH (its product)
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Inhibition of B-ketothiolase by?
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Acetyl CoA (its product)
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Carnitine deficiencies
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Decreased ability of tissues to utilize long-chain fatty acids
Accumulation of toxic amounts of FA |
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Medium-chain fatty acyl CoA dehydrogenase (MCAD) deficiency
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-4 specific fatty acyl CoA dehydrogenases
-Common inborn error of metabolism -Decrease FA oxidation-->hypoglycemia -Treatment: carbohydrate-rich diet |
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Excess oxidation
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When fat is the main energy source (starvation, diabetic)
Produce ketone bodies |
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Cis vs. trans FA
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-Cis double bonds increase membrane fluidity and trans double bonds pack well and decrease fluidity.
Accumulate in the membrane |
