Term
| What is the primary energy source for the body and why? |
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Definition
Fatty acids
-more compact storage than glycogen
-stored in specialized cells
-unlimited capacity for storage |
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Term
| Where does fatty acid synthesis and degradation occur? |
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Definition
synthesis- cytoplasm
degradation- mitochondria |
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Term
| What is derived from fatty acid degradation to use as an alternative energy source for glucose? Why is this used? |
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Definition
| ketone bodies- used when glucose supplies are limiting |
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Term
| Why is fatty acid storage more compact than glycogen storage? |
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Definition
| hydrophobic effect in fatty acids |
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Term
| Fatty acids have both a polar head and a hydrophobic tail, what is this called? |
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Definition
| the molecules are amphipathic |
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Term
| How little and how long can the fatty acid tail be? |
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Definition
| As little as 3 carbons up to 24 carbons |
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Term
| What is the common name for C16:0? |
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Definition
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Term
| What is the common name for cis-∆9-C16:1? |
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Definition
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Term
| What is the common name for C18:0? |
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Definition
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Term
| What is the common name for cis∆9-C18:1? |
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Definition
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Term
| What is the common name for cis∆9,12-C18:2? |
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Definition
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Term
| What is the common name for cis∆9,12,15-C18:3? |
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Definition
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Term
| What is the common name for cis∆5,8,11,14-C20:4? |
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Definition
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Term
| What are three of the main biological functions of fatty acids? |
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Definition
1) energy storage in the form of triacylglycerol
2) membrane structure (as a component of phospholipids)
3) second messengers (prostaglandins, thromboxanes are derived from fatty acids) |
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Term
| What consists of a glycerol molecule to which is esterified three fatty acids? |
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Definition
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Term
| Are the fatty acids at the three positions in triacylglycerols the same? |
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Definition
| No, they don't have to be. |
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Term
| What is the first step in the activation of adipocytes? It leads to the production of glycerol and free fatty acids(FFA)? |
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Definition
| Activation of Hormone-sensitive lipase(HSL) |
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Term
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Definition
| PKA- phosphorylates it, thus another function of the cAMP |
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Term
| Does HSL remove all 3 FFA? |
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Definition
| No, it removes the first one and the other two are removed by non-regulated lipases |
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Term
| FFA released from the adipocyte travel to tissues bound to? |
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Definition
| serum albumin in the blood |
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Term
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Definition
| conversion to DHAP in the liver |
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Term
| ß-oxidation oxidizes how many carbons at a time? |
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Definition
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Term
| Can the brain do ß-oxidation? |
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Definition
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Term
| What other pathway utilizes ß oxidation? |
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Definition
| TCA cycle- generation of succinyl-CoA |
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Term
| Where is fatty acid activated and what makes it active? |
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Definition
| activated to acyl-CoA derivative in the cytoplasm (side not, its bound to a fatty acid binding protein to increase solubility) |
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Term
| What helps fatty get into the mitochondria? |
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Definition
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Term
| How many high energy bonds are required for fatty acid activation? |
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Definition
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Term
| What enzyme gets Acyl-CoA into the mitochondria? |
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Definition
| Carnitine Acyl-Transferase I (CAT-I) |
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Term
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Definition
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Term
| If a person has CPT-II deficiency, what would happen? |
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Definition
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Term
| What are the four main enzyms in fatty acid oxidation? |
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Definition
1) Acyl-CoA dehydrogenase- makes FADH2
2) Enyl-CoA hydrate
3) L-3-hydroxyacyl CoA dehydrogenase- makes NADH
4) ß-ketothilolase- makes Acetyl-CoA |
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Term
| There are many isoforms of which enzyme from ß-oxidation? |
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Definition
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Term
| What are the different isoforms of Acyl-CoA Dehydrogenase and what do they work on? |
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Definition
SCAD- 4-8
MCAD- 8-12
LCAD- 14-20
VLCAD- >20 |
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Term
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Definition
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Term
| What happens to the electrons from FADH2 in the peroxisome created by VLCAD? |
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Definition
| reduce O2 to H2O2 (catalase converts H2O2 to H2O and O2) |
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Term
| Why are very long chain fatty acids such a poor source of energy? |
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Definition
| They are digested in the peroxisome and some of the electrons bypass the ETC, instead used to create H2O2, and the fatty acid won't go to the mitochondria until it is about 8 carbons in length, so a lot of potential energy is lost. |
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Term
| What uses NADPH and reduces are fatty acid molecule? |
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Definition
| 2,4 Dienoyl-CoA Reductase(used for unsaturated fatty acid degradation) |
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Term
| What moves a double bond in unsaturated fatty acids? |
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Definition
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Term
| Unsaturated fatty acid, what is the effect of an odd numbered double bond? |
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Definition
-Only use the isomerase rxn
-lose step at which FADH2 is produced
- loss of 1.5 ATP compared to a saturated fatty acid of the same length |
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Term
| Unsaturated fatty acid, what is the effect of an even numbered double bond? |
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Definition
-Use up and NADPH; all other steps are the same
- loss of 2.5 ATP as compared to a saturated fatty acid of the same length |
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Term
| What is produced instead of acetyl-CoA at the end of an odd-chain fatty acid oxidation? |
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Definition
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Term
| What is produced instead of acetyl-CoA at the end of an odd-chain fatty acid oxidation? |
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Definition
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Term
| What will propinoyl-CoA enter the TCA cycle after undergoing processing? What cofactors are required in this processing? |
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Definition
It will enter as succinyl-CoA
Requires biotin and B12 |
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Term
| What three enzymes are required to process Propinoyl-CoA into succinyl-CoA? |
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Definition
1) Propinoyl-CoA Carboxylase (uses ATP; requires biotin)
2) Racemase
3) Methyl-malonyl-CoA Mutase (requires B12) |
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Term
| How much ATP is produced from propinoyl-CoA? |
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Definition
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Term
| What will accumulate in the blood in an individual with MCAD deficiency? |
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Definition
| 6-10 carbon dicarboxylic acids |
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Term
| Tell me more about alpha-oxidation? |
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Definition
1) oxidize alpha carbon of branched cain fatty acids
2) create a-keto acid, which then undergoes oxidative decarboxylation |
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Term
| Tell me more about mega-oxidation? |
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Definition
-omega-carbon oxidized to alcohol, then to aldehyde, then to carboxylic acid
-used to get energy from fatty acids, when ß-oxidation not occuring, primarily due to disease |
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Term
| How does fatty acid derived FADH2 deliver e- to the ETC? |
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Definition
-Uses ETF(electron transfer flavoprotein)-contains a bound FAD
-ETF will then directly transfer the e- to CoQ via ETC-CoQ oxidoreductase enzyme |
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Term
| What is produced in the liver when Acetyl-CoA levels are elevated? |
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Definition
| ketone bodies- when glucose supplies are limiting |
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Term
| What are some of the ketone bodies? |
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Definition
1) acetoacetic acid
2) ß-hydroxy butyric acid
3) acetone (we can't deal with it directly so its exhaled) |
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Term
| What is an intermediate in cholesterol synthesis that is made in ketone biosynthesis? |
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Definition
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Term
| When is ß-hydroxy butyrate made? |
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Definition
| Only when the NADH/NAD+ ratio is high within the mitochondria; it is reconverted to acetoacetate for metabolism |
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Term
| Acetoacetate is metabolized everywhere except the______, and it is metabolized by which enzyme? |
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Definition
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Term
| What happens to glucose levels when ketone body levels rise? |
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Definition
| glucose levels drop to about 70% of normal |
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Term
| Defects in Fatty Acid Oxidation: What happend when lacking ETF(Electron Transfer Flavoprotein) or ETF:CoQ Oxidoreductase? |
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Definition
| Both are usually fatal- not enough energy generation fro fatty acid oxidation |
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Term
| Defects in Fatty Acid Oxidation: What happens with a Carnitine deficiency? |
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Definition
-Inability to transport activated fatty acids into the mitochondria: weakness, cramping
-Treat by adding carnitine to the diet |
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Term
| Defects in Fatty Acid Oxidation: What happens with a MCAD deficiency? |
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Definition
-Affects 1/15,000 live births (similar to PKU)
-Glu to Lys mutation due to a single base change; charge difference, unstable prtoein
-Hypoglycemia results when glycogen stores are low
--Cannot obtain full energy from fatty acid oxidation (hexanoylglycine also accumulates: hexanoyl-CoA + glycine, a catalyzed reaction)
--Insufficient energy to allow gluconeogenesis to continue
--ketone bodies not formed due to a lack of acetyl-CoA |
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Term
| What are the two substrates for fatty acid biosynthesis? |
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Definition
| acetyl-CoA and Malonyl-CoA |
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Term
| What enzyme forms Malonyl-CoA from acetyl-CoA in one step? |
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Definition
| Acetyl-CoA Carboxylase (uses ATP and requires Biotin)- this is a regulated step- |
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Term
| When does a build-up of acetyl-CoA occur? |
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Definition
| when malate is leaving for gluconeogenesis |
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Term
| What does unripe Ackee(jamaican fruit) do to you? |
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Definition
| It blocks ß-oxidation and makes you sick and can lead to death of children |
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Term
| All carboxylase reactions require what cofactor? |
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Definition
| Biotin; except for in blood clotting which requires Vit K |
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Term
| What does Fatty acid biosynthesis require for the reduction reactions? |
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Definition
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Term
| Where does fatty acid elongation occur? |
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Definition
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Term
Desaturation of fatty acids...
1) where are the enzymes located
2) requires what?
3)what is oxidized in this rxn?
4) what is reduced in this rxn? |
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Definition
1) located in the ER
2) requires cytochrome b5
3) NADH and fatty acid are oxidized
4) O2 is reduced to water |
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Term
| Where can insert double bonds? |
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Definition
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Term
| What are the essential fatty acids? |
|
Definition
Linoleic acid- cis∆9,12 C18:2
Linolenic acid- cis ∆9,12,15 C18:3 |
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Term
What enzyme does this rxn and where does it occur?
Acetyl-CoA + OAA--> citrate |
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Definition
| Citrate synthase in the mitochondria |
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Term
What enzyme does this rxn and where does it occur?
Citrate + ATP-->OAA + acetyl-CoA +ADP +Pi |
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Definition
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Term
What enzyme does this rxn and where does it occur?
OAA +NADH--> malate + NAD+ |
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Definition
| Malate dehydrogenase- in cytosol for transport of acetyl-CoA, but this rxn in mitochondria for TCA cycle |
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Term
What enzyme does this rxn and where does it occur?
Malate + NADP+ --> Pyruvate + CO2 + NADPH |
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Definition
| Malic enzyme- in the cystosol |
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Term
What enzyme does this rxn and where does it occur?
Pyruvate +ATP +CO2 --> OAA + ADP +Pi |
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Definition
| Pyruvate Carboxylase- in the mitochondria |
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Term
| What enzymes of fatty acid metabolism are subject to long-term adaptation? |
|
Definition
1) Fatty acid synthase
2) Acetyl-CoA carboxylase
3) Citrate Lyase
4) Malic enzyme
5) Glucose-6-phosphate dehydrogenase |
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Term
| How long does it take for long-term adaptation to occur in fatty acid metabolism? What causes this adaptation? |
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Definition
| It takes 2-3 weeks, in result to a higher/lower calorie diet |
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Term
| HSL (hormone sensitive lipase) is hormonally regulated by? |
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Definition
| PKA-phosphorylated and activated-leads to fat oxidation;ie we need energy |
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Term
| Acetyl-CoA Carboxylase is hormonally regulated by? |
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Definition
| AMP activated protein kinase- it is inactivated; ie energy is low, we don't need fat synthesis (muscle does the same thing) |
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Term
| Insulin promotes the dephosphorylation of? |
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Definition
1) HSL
2) acetyl-CoA carboxylase
ie-too much glucose, make some fat |
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Term
| HSL has allosteric regulation from? |
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Definition
| ketone bodies-inhibits slightly |
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Term
| Acetyl-CoA has allosteric regulation from? |
|
Definition
| citrate-activator (don't forget citrate inhibits PFK-I) |
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Term
|
Definition
| malonyl-CoA (to prevent futile cycles) |
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|
Term
| malonyl-CoA decraboxylase is activated in the muscle by? |
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Definition
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Term
| From what we have learned so far...what happens when glucagon is released? |
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Definition
1) Adenylate cyclase activated, cAMP levels rise
2) PKA activated
3) HSL phosphorylated and activated, fatty acids are released for travel to the tissues(bound to serum albumin)-sidenote epinephrine more effective at working on adipocytes
4) Glycogen phosphorylase is activated (glycogen synthase inactivated) to generate glucose from glycogen
5) PFK-2, PK phosphorylated-inactivated in liver so glycolysis inhibited( gluconeogenesis favored)
6) Acetyl-CoA carboxylase inactivated by phosphorylation by AMP dependent kinase; fatty acid oxidation favored, also provides energy for gluconeogenesis |
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