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Biochem > Biochem Exam 1: Set 3 (TCA Cycle, Electron Transport) > Flashcards

Biochem Exam 1: Set 3 (TCA Cycle, Electron Transport) Flashcards

1
Q

If there is a positive change in free energy, what direction will the reaction move?

A

reverse direction

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2
Q

What are ways to drive an energetically unfavorable reaction (positive delta G)?

A

add substrate or remove product

couple the reaction with an energetically favorable one

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3
Q

How many high-energy electrons result from one turn of the citric acid cycle?

A

8

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4
Q

What are sources of Acetyl-CoA?

A

fatty acids, ketone bodies, pyruvate (from glucose and amino acids), ethanol

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5
Q

What are the outputs of one turn of the TCA cycle?

A

2 CO2
1 GTP
3 NADH
1 FADH2

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6
Q

What is the final electron acceptor in the electron transport chain?

A

oxygen

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7
Q

What enzyme catalyzes the conversion from pyruvate to acetyl CoA?

A

Pyruvate Dehydrogenase Complex

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8
Q

What is the net reaction catalyzed by pyruvate dehydrogenase complex?

A

pyruvate + CoA + NAD+ –> acety CoA + CO2 + NADH

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9
Q

What are the cofactors for the reaction catalyzed by pyruvate dehydrogenase complex?

A

thiamine pyrophosphate

lipoic acid, FAD

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10
Q

How many subunits do alpha-keto acid dehydrogenase complexes have?

A

3 (E1, E2, E3)

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11
Q

Arsenate/Arsenite effect what subunit of PDC and alpha-ketoglutarate dehydrogenase complex?

A

E2

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12
Q

Vitamin B1 is a component for what subunit of alpha-keto acid dehydrogenase complexes?

A

E1 (TPP)

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13
Q

What are the regulators of PDC?

A 
\+phosphatase
\+Ca2+
\+pyruvate
\+NAD+
-ADP
-acetyl CoA
-NADH
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14
Q

What are the components of TCA cycle…

A

citrate–>isocitrate–>alpha-ketoglutarate–>succinyl CoA–>succinate–>fumarate–>malate–>oxaloacetate

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15
Q

What are the enzymes of TCA cycle…

A

citrate synthase, aconitase, isocitrate dehydrogenase, a-ketoglutarate dehydrogenase, succinate thiokinase, succinate dehydrogenase, fumarase, malate dehydrogenase

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16
Q

Which steps in the TCA cycle produce NADH?

A

isocitrate dehydrogenase, a-ketoglutarate dehydrogenase, malate dehydrogenase

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17
Q

Where is FADH produced in the TCA cycle?

A

succinate dehydrogenase

18
Q

Where is GTP produced in the TCA cycle?

A

succinate thiokinase

19
Q

Where is CO2 produced in the TCA cycle?

A

isocitrate dehydrogenase, a-ketoglutarate dehydrogenase

20
Q

What are the regulators of the TCA cycle?

A

+ADP
+Ca2+
-NADH
-citrate

21
Q

What are the key regulatory steps of the TCA cycle?

A

citrate synthase, isocitrate dehydrogenase (biggest regulatory step), a-ketoglutarate dehydrogenase, malate dehydrogenase

22
Q

What intermediates in the TCA cycle can be replenished?

A

oxaloacetate (by pyruvate), a-ketoglutarate (by glutamate), succinyl CoA (by propionyl CoA from odd-chain fatty acid oxidation)

23
Q

What are the two ways to make ATP?

A

substrate level phosphorylation, oxidative phosphorylation (electron-transport chain)

24
Q

How is NAD+ reduced to NADH?

A

accepts 2 electrons and 1 H+ (a hydride ion)

25
Q

How is FAD reduced to FADH?

A

accepts 1 electron and 1 H+

26
Q

What vitamin is necessary to make NAD/NADH, and what are symptoms from a deficiency in this vitamin?

A

Niacin (B3)

B3 deficiency = pellagra: dermatitis, dementia, diarrhea

27
Q

What are the five complexes of the electron transport chain?

A
  1. NADH Dehydrogenase
  2. Succinate-Q reductase
  3. Cytochrome bc1 complex
  4. Cytochrome C oxidase
  5. ATP Synthase
28
Q

What are the two mobile electron carriers in the inner-mitochondrial membrane?

A

Coenzyme Q

Cytochrome C

29
Q

What metals are required in the electron transport chain?

A

Copper and Iron

30
Q

What portion of the mitochondria has the highest concentration of protons?

A

intermembrane space

31
Q

How many protons are pumped across the membrane by each complex in the ETC?

A 
1 = 4 H+
2 = 0 H+
3 = 4 H+
4 = 2 H+
32
Q

Which reducing agents are used by complexes 1 and 2 in the ETC?

A

Complex 1 = NADH

Complex 2 = FADH

33
Q

How many protons are required to synthesize one ATP

A

4 H+

3 to turn ATP synthase and 1 to pump ATP out of mitochondria

34
Q

How does ADP get into the mitochondrial matrix?

A

ATP-ADP translocase

35
Q

How do cyanide and CO disrupt ETC?

A

bind to heme iron in Complex 4 and stop final transfer of electrons to oxygen

36
Q

If complex 1 is inhibited what happens to ATP production through oxidative phosphorylation?

A

ATP production is decreased but not halted entirely. Electrons can enter the ETC through complex 2, but the 4 protons transferred by complex 1 do not occur.

37
Q

How do uncoupling agents effect ATP synthesis?

A

movement of proton not linked to ATP synthesis, energy is lost to heat (brown fat)

38
Q

Why does hypoxia lead to acidosis?

A

NAD+ is regenerated from NADH anaerobically and lactic acid is produced

39
Q

What are the dangers of aspirin overdose?

A

Aspirin degradation produces salicylate which is lipid soluble and has a dissociable proton and can act as an uncoupling agent by ferrying protons across the inner mito. membrane

40
Q

How many ATP are synthesized per oxygen consumed

A

2.5

41
Q

How many ATP are produced per glucose molecule?

A

30-32 (depending on method of NADH transport)

42
Q

Why are mitochondrial genetic disorders due to mutations in mitochondrial encoded genes?

A

DNA repair mechanisms aren’t as good in the mitochondria as in the nucleus, and inheritance from mother prevents homozygous recessive disorders from being silent in offspring as a heterozygous genotype

Biochem (6 decks)

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