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MCB II Block 2 > TCA Cycle > Flashcards

TCA Cycle Flashcards

1
Q

TCA cycle produces

A

1 GTP
3NADH/1FADH2
2Co2

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2
Q

pyruvate - what corresponding a.a.

A

alanine

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3
Q

what is a.a. for oxaloacetate

A

aspartate

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4
Q

pyruvate is precurser to what a.a

A

alanine

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5
Q

αketoglutarate is precurser to what a.a

A

glutamate

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6
Q

what is start ot TCA

A

pyruvate

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7
Q

pyruvate only produced by

A

glucose

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8
Q

pyruvate dehydrogenase converts pyruvate to

A

acetyla CoA

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9
Q

for pyruvate to get into mitochondria needs what transporter

A

secondary active transport

uses the gradient of hydrogen to transport pyruvate against concentration grdient

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10
Q

pyruvate dehydrogenase complex of many genes coming together for form complex molecule with what three activities

A

pyruvate dehyrogenase
dihydrolipoyl transacetylase
dihydrolipoyl dehydrogenase

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11
Q

in TCA pyruvate acts as a

A

co-enzyme

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12
Q

write out the steps of pyruvate dehyrogenase complex

A

pg 6

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13
Q

what are products of pyruvate dehyrogenase complex

A

NADH + H+

CO2

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14
Q

PDC stands for

A

pyruvate dehydrogenase complex

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15
Q

PDH kinase inactivates

A

pyruvate dehydrogenase complex

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16
Q

pyruvate dehydrogenase complex inhibited by

A

acetyl CoA, NADH

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17
Q

pyruvate dehydrogenase complex activated by

A

CoA, NAD+

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18
Q

PDH phosphatase activates

A

pyruvate dehydrogenase complex

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19
Q

affect mitochondria in any way you have

A

lactic acidosis

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20
Q

PDH deficiency what are consequences

A

progressive psychomotor retardation often with damage to brainstem & basal ganglia.
Brain dependent on glycolysis for energy & sensitive to acidosis.

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21
Q

brain is sensitive to

A

acidosis and low glucose

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22
Q

common mutation for PDH defiicency is located where

A

X-linked

when girls haveit symptoms not as bad - boys have it more severly

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23
Q

PDH deficiency is a type of subacute necrotizing encephalomyelopathy called

A

Leigh Syndrome/disease

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24
Q

pyruate carboxylase, pyruate to

A

pyruvate to oxaloacetate

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25
Q

intermediates of TCA cycle called what kind of reaction

A

anapleoritc

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26
Q

any reactions that produce intermeciate of TCA cycle called

A

anapleoritc rxn

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27
Q

arsenate

A

acts on glycolysis by competing with Pi

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28
Q

acetyl-CoA unique bc it can come from

A

a.a
fatty acid
glucose

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29
Q

if you eat extra carbohydrates you will produce fat b/c of

A

acetyl-CoA

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30
Q

list sequence of events in the citric acid cycle

A

pg 14

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31
Q

coenzyme A

A

nucleotide with purine, ribose, phosphoester, etc. it is a nucleotide . coenzyme A is attached to acetyl to form acetyl-CoA

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32
Q

hyrolysis of thioesters is strongly

A

favorable

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33
Q

what is an important donor of acyl groups

A

acetyl co-a

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34
Q

what is formed by condensation of acetyl-CoA and oxaloacetate

A

C-C bond

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35
Q

why is acetyl CoA ready to go more than glucose

A

the thioester is ready to go - it is a high energy bond. it comes from fat, carbs, a.a

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36
Q

acetyl CoA + oxaloacetate + citrate synthase is reversible or irreversible

A

irreversible step

37
Q

draw out the allosteric regulation os isocitrate dehydrogenase

A

pg 20 - draw mech on right

38
Q

what inhibits isocitrate dehydrogenase

A

ATP

NADH

39
Q

if inihbit isocitrate dehydrogenase what accumulates

A

citrate

40
Q

how does NADH affect rate of isocitrate dehydrogenase

A

affects the allosteric activation

41
Q

α ketoglutarate is

A

ketoacid

42
Q

ketoacid is precurser for

A

a.a. → glutamate

43
Q

pyruvate is a

A

ketoacid

44
Q

pyruvate dehyrogenase uses same tools as

A

α ketoglutarate dehydrogenase complex

45
Q

how does arsenite poisioning affect α ketoglutarate dehydrogenase complex

A

disables lipoic acid

46
Q

α ketoglutarate dehydrogenase has same mechanism as

A

pyruvate dehyrogenase complex

oxidation of isoleucine(pg 22)

47
Q

write out steps of TCA

A

biochem book

make diagram & look through his slides and add important steps

48
Q

succinate dehydrogenase contains covalently bound

A

FAD

49
Q

succinate dehydrogenase is found where

A

inner mitochondrial membrane

50
Q

fumarate is hydrated to malate by

A

fumarase

51
Q

besides TCA where is fumarate produced

A

urea cycle
purine synthesis
catabolism of Phe, Tyr

52
Q

malate is one of the few molecules that can

A

go in and out of mitochondria

53
Q

malate to oxaloacetate -describe its favorability

A

unfavorable, it wants to stay as malate

54
Q

how does cell move malate to oxaloacetate

A

the concentration of oxaloacetate is very small to help pull rxn forward

55
Q

concentration of oxaloacetate in cell is

A

very low, it helps pull the reaction forward

56
Q

what are the inhibitors of citric acid cycle

A

NADH & ATP

57
Q

what are the activators of citric acid cycle

A

NAD+ and AMP

58
Q

fatty acids produce a lot of

A

acetyl-CoA

59
Q

if a lot of acetyl-Coa is produced (fatty acid) what happens to affinity of enzyme

A

it goes down, you don’t need pyruvate to be converted to acetyl-CoA when you already have a lot of acetyl-CoA coming from fatty acids

60
Q

acetyla CoA processing by TCA cycle produces how much ATP

A

10 mol

61
Q

NADH = how many ATP

A

2.5

62
Q

FADH2= how many ATP

A

1.5

63
Q

TCA intermediates are

A

amphibolic and exergonic

64
Q

TCA intermediates are amphibolic - intermediates from TCA can be used

A

for things besides energy, the intermediates can go off and do synthesis of something else

65
Q

if pulling a lot of intermediates out of TCA cycle what happens to speed/direction of TCA

A

it will slow down, need to replenish the intermediates

66
Q

anaplerotic reactions

A

substrate and produce intermediates of TCA cycle

67
Q

pyruvate carboxylase uses pyruvate, HCO3-, ATP to produce

A

oxalocetate + ADP + P

68
Q

PEP carboxykinase produces

A

oxalocetate

69
Q

how does arsenate act on glycolysis

A

competes with Pi

70
Q

how does arsenite act on TCA

A

disables PDC

71
Q

besides pyruvate, how is Acetyl CoA made

A

fatty acids

amino acids

72
Q

how does Acetyl-CoA donate acyl groups

A

feeding two-carbon units into metabolic pathways

synthesis of fatty acids

73
Q

in TCA cycle what is the only reaction with C-C bond formation

A

the first one - acetyl-Coa + oxaloacetate → citrate

74
Q

during the first rxn in TCA oxaloacetate acts as a

A

electrophile

75
Q

fluoroacetate inhibits

A

aconitase (step 2)

76
Q

draw out TCA cycle

A

yay

77
Q

where is the first oxidation of TCA

A

step# 3 with isocitrate dehydrogenase

78
Q

what activates isocitrate dehydrogenase

A

ADP

Ca2+

79
Q

what inhibits isocitrate dehydrogenase

A

ATP

NADH

80
Q

how do isocitrate, NAD+ and NADH bind to isocitrate dehyrogenase

A

active site

81
Q

how do ADP and Ca2+ bind to isocitrate dehydrogenase

A

bind separate allosteric sites

82
Q

what does ADP do to isocitrate dehydrogenase

A

ADP induces all subunits to be in their active conformation & reduces Km

83
Q

what does NADH do to isocitrate dehydrogenase

A

NADH (a product of the reaction) reduces the rate by affecting the allosteric activation

84
Q

what does ADP do to Km when it binds to isocitrate dehydrogenase

A

reduces Km aka it makes the enzyme work better by affecting the allosteric activation

85
Q

where is second oxidation in TCA

A

step#4

α-ketoglutarate →succinyl-CoA

86
Q

what are cofactors in step# 4 α-ketoglutarate →succinyl-CoA

A

thiamine pyrophosphate, lipoic acid, FAD, NAD+, CoA as co-factors

87
Q

what inhibits α-ketoglutarate dehydrogenase complex

A

NADH & succinyl CoA

88
Q

what activates α-ketoglutarate dehydrogenase complex

A

Ca2+

MCB II Block 2 (10 decks)

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