TCA Cycle
Terms
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- What are the two oxidative decarboxylation reactions
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pyruvate --> acetyl CoA
α-ketogluterate -->Succinyl CoA - What are the 5 coenzymes required for oxidative decarboxylation in the TCA cyclle
- TPP (thiamine pyrophosphate), Lipoic acid, CoA, FAD, NAD+
- dihydrolipoyl transacetylase
- E2 in the oxidative decarboxylation reactions. Lysine of the enzyme forms an amide bond with the carboxyl group of lipoic acid
- 2 functions of Coenzyme A
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1. universal carrier of acyl groups
2. forms activated thioesters - Pantothenic Acid
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A B-vitamin that is part of coenzyme A
Cannot be synthesized by humans
No known deficiency - Structural components of Coenzyme A
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3'P-ADP
Pantothenic Acid
β-mercaptoethylamine (contains reactive SH) - Niacin deficiency
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Pellagra
Symptoms: dermatitis, diarrhea, and dimentia - Thiamine Deficiencies
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Beriberi: dry and wet
Wernicke-Korsakoff: defective transketolase with less affinity for TPP - Riboflavin
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Vitamin B2
component of FAD and FMN
contains isoalloxanine rind and C5 ribitol
no major deficiencies associated - Intracellular location of the electron transport chain
- inner mitochondrial membrane
- What are the inhibitors of the ETC and where specifically do they act
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Rotenone: FP1 --> CoQ
Sodium Amytal: FP1 --> CoQ
Antimycin A: Cytb --> CytC1
Cyanide: Cyt (a+a3) ---> oxygen
Sodium Azide: Cyt (a+a3) ---> oxygen
Carbon Monoxide: Cyt(a+a3) ---> oxygen - What are the distinguishing features of CoenzymeQ
- It's a lipid, not a protein and is not permanetly bound to the membrane. It's a mobile carrier of electrons between complexes I, II, and III
- What are 4 uncouplers of oxidative phosphorylation
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1. 2,4-dinitrophenol
2. dicumarol
3. fatty acids in brown adipose tissue
4. uncoupling proteins - What are the components of the 4 complexex in the ETC
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I: FMN, and FeS (aka FP1)
II: FAD and FeS (aka SDH)
III: Cytb, Cytc1, FeS
IV: Cyt (a+a3), Cu2+ (aka cytochrome oxidase) - How does ADP regulate oxidative phosphorylation
- Exerts respiratory control; electrons are transfered to oxygen only if ADP is phosphorylated to ATP. The entry of ADP into the mitochondria requires the exit of ATP via facilitated exchange diffusion, which can be inhibited by atractyloside
- Atractyloside
- An inhibitor of the carrier protein that transports ADP into the mitochondria. Stops oxidative phosphorylation due to a lack of ADP
- Chiemiosmotic Hypothesis
- Movement of e- down the ETC liberates energy that is used to pump H+ out of the cell. This gradient is then used to drive ATP Sythase and make ATP.
- Oligomycin
- Inhibits ATP Synthase