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16 Cards in this Set
- Front
- Back
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Describe 1st step of B-oxidation of very long chain FA in Peroxisomes?
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1st step of of B-oxidation is catalized by an FAD containing oxidase. e- are transfered from FADH2 to O2 which is then reduced to H2O2
Takes place in peroxisome because H2O2 is produced |
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What are similarities & differences of mitochondrial vs peroxisomal B-oxidation?
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Both generate FADH2 & NADH but
Peroxisomal is less efficient because FADH can’t get through peroxisomal membrane (must be oxidized by O2) |
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Why do peroxysomal B-oxidation?
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very long chain FA cannot cross mit membrane, must be broken up by peroxysomes
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Describe oxydation of phytanic acid?
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a peroxysomal alpha hydroxylase oxidizes the alpha carbon so that B oxidation can occur.
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Refsum's disease
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alpha oxidase enzyme is defective so we cannot break down phytanic acid
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w-oxidation of FA
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converts FA to dicarboxylic acids. Results in DC urea. Which is diagnostic for problem w/ B oxidation
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4 steps of B-oxidation
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1)Oxidation (ACoA dehyd)
2)Hydration (enol CoA hyd) 3)Oxidation(B hydroxy CoA hyd) 4)Cleavage (B keto thiolase) |
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Metabolism of Monosaturated Fats
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2-3 enol-CoA isomerase - converts cis bond to trans
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Metabolism of Polyunsaturated Fats
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2-3 enol-CoA isomerase - converts cis bond to trans
2-4 dienol Co A reductase – reduces one of the double bonds |
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Propynyl Co A pathway
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Propionyl CoA to Succinyl CoA. 1st step involves Propionyl CoA carboxylase (ABC enzyme) conversionof Propionyl CoA to methmylmalonyl CoA. Last step involves methyl-Malonyl CoA mutase conversion of Methylmalonyl CoA to Succinyl CoA. This last enzyme requires B12 therefore build up of Methylmalonyl CoA is diagnostic for B12 deficiency.
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ABC enzymes
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ABC
Pyruvate carboxylase - Acetyl CoA carboxylase - Propionyl CoA carboxylase - |
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MCAD deficiency
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B oxidation in liver tissue in order for gluconeogenesis – if can’t do B-oxidation – hypoglycemic shock;
Feed child, replenished glycogen stores, in night using glycogen stores, next morning feed – child never in hard glucagon world. Never know about deficiency. Using liver glycogen always. When glycogen stores don’t get built up child needs to do gluconeogenis need to do B oxidation – usually dies in middle of night. |
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3 ketone bodies:
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1)Acetoacetate can covert to:
2)Acetone (volitile) 3)D-B Hydroxybutyrate (more stable) |
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Why are ketone bodies made in liver cells only?
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HMG Co A synthase –makes ketone bodies and found only in liver mitochondria
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Why are ketone bodies broken down in tissues other than the liver
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B-ketoacyl- CoA transferase is found in mitochondria outside liver -allows extrahepatic tissues to break ketone bodies down
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Fuel for Brain
1) 24 hours 2)day 2-7 3) After 1 week |
1)glycogen
2) protein (mostly glucose from gluconeogenesis but some ketone bodies) 3)Fat & small amount of protein-mostly ketone bodies but some glucose from gluconeogenesis |
