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Biochemistry > TCA Cycle > Flashcards

TCA Cycle Flashcards

(88 cards)

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1
Q

What vitamin is succinate dehydrogenase derived from

A

Riboflavin

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2
Q

FAD and FMN are coenzymes for

A

Succinate dehydrogenase

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3
Q

What is a cofactor for pyruvate dehydrogenase

A

Thiamine pyrophosphate (B1)

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4
Q

What is the nicotinamide ring on NAD+?NADH derived from

A

Niacin B3

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5
Q

CoA is derived from

A

Pantothenic acid

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6
Q

Cofactor for pyruvate carboxylase

A

Biotin B7

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7
Q

What does pyruvate carboxylase do

A

Converts pyruvate to oxaloacetate when cycle is low on components

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8
Q

Pyruvate to acetyl CoA

A

Pyruvate dehydrogenase

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9
Q

Pyruvate to oxaloacetate

A

Pyruvate carboxylase

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10
Q

What enzyme is embedded in the mitochondrial membrane?

A

Succinate dehydrogenase

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11
Q

What complex is succinate dehydrogenase in

A

Complex II of ETC

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12
Q

What is the thioester bond in succinyl coA cleaved by

A

Succinate thiokinase

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13
Q

What is succinate thiokinase used for

A

Synthesis of high energy phosphate bond for GTP

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14
Q

What is in the a-keto acid dehydrogenase complex protein family

A

a-ketogluturate dehydrogenase complex
Pyruvate dehydrogenase complex
Branched chain amino acid dehydrogenase complex

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15
Q

Sources for acetyl coA

A

fatty acids (palmitate)
ketone body (acetoacetate)
Sugar (glucose)
Pyruvate
Alanine
Ethanol

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16
Q

E1

A

a-keto acid decarboxylase
Contains TPP
Cleaves off Co2

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17
Q

E2

A

Transacyclase containing lipoic acid
Transfers acyl of a-keto acid from thiamine–>CoASH–> produces acetyl coA

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18
Q

E3

A

Dihydrolipoyl dehydrogenase contains FAD—> reduces it to NAD+—> generates NADH

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19
Q

Succinate dehydrogenase is derived from

A

B2 Riboflavin

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20
Q

Pyruvate dehydrogenase and a-ketogluatare dehydrogenase contain

A

TPP B1

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21
Q

What happens to the lipoate on E2 in pyruvate dehydrogenase

A

It is reduced when it accepts the acyl group from E1

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22
Q

Which vitamins are necessary for decarboxylation of a-ketoglutarate

A

B1, 2, 3, 5

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23
Q

What is derived from coenzyme A

A

B5 pantothenic acid

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24
Q

Which enzyme involves TPP (B1)

A

a-ketoglutarate dehydrogenase

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25
Lipoate is attached to what
e-amino group of lysine of transacylase enzyme
26
What form is transylase enzyme
E2
27
What happens to the oxidized lipoate disulfide form
Reduced, accepts acyl group from TPP
28
Arsenic poisioning
Lipoic acid is a target of arsenite inhibition due to binding of -SH groups
29
Which enzymes produce NAD+/NAH
Malate dehydrogenase, a-ketoglutarate, isocitrate dehydrogenase
30
What is a-ketoglutarate dehydrogenase derived from
TPP
31
Which part of the TCA is positive delta G
Citrate to isocitrate Malate to OAA
32
What is citrate synthase controlled by
Concentration of AA, substrate, and citrate
33
What is citrate an inhibitor of
Product inhibitor, Its competitive with OAA
34
Isocitrate dehydrogenase is activated by ____ during muscular contraction
Ca++
35
Isocitrate dehydrogenase is allosterically activated by
ADP
36
Isocitrate dehydrogenase is inhibited by
NADH
37
What is a-ketoglutarate dehydrogenase inhibited by
NADH, succinyl CoA, GTP
38
What is a-ketoglutarate dehydrogenase activated by
Ca++
39
Two functions of TCA cycle
1. maintaining cellular ATP homeostases 2. Regulating concentration of TCA cycle intermediates
40
What happens when TCA intermediates are removed from cycle
Intermediates are depleted, less NADH and FADH2 for oxphos
41
Intermediate for amino acid synthesis
OAA, a-ketoglutarate dehydrogenase
42
Intermediate for Gluconeogenesis
Malate
43
Intermediate for FA synthesis
Citrate
44
Intermediate for Amino acid synthesis and neurotransmitter
a-ketoglutarate
45
Intermediate for heme synthesis
Succinyl coA
46
What happens if there is excess citrate
Gets split back into OAA and acetylCoA Acetyl coa becomes FA which bundles into TG TG gets stored for fat Acetylcoa becomes cholesterol
47
Major anaplerotic enzyme
Pyruvate carboxylase
48
Pyruvate carboxylase is activated by
Acetyl CoA
49
What reactions refill the cycle and produce TCA intermediates
Anaplerotic reactions
50
What provides key substrates for anaplerotic pathways
Amino acids and odd chain fatty acids
51
What are two major anaplerotic pathways
1. Amino acids --> pyruvate --> OAA (generates ATP) 2. Odd chain fatty acids --> valine, isoleucine --> propionyl CoA --> succinyl CoA
52
Pathway from
53
What does TCA produce
MOST of CO2 3 NADH 1 FADH 2H 1 OAA
54
What does glycolysis produce
2 pyruvates yields 2 acetyl coa via pyruvate dehydrogenase complex
55
What activates PDC active form
NAD+ Pyruvate
56
What inactivates PDC
NADH Acetyl CoA
57
An accumulation of ADP and pyruvate does what to PDC
Inhibits PDC kinase, activates PDC
58
An accumulation of NADH and acetyl coA does what to PDC
Activates PDC kinase, inactivates PDC
59
An accumulation of calcium does what to PDC
Activates posphatase, actives PDC
60
Which enzymes make NADH
Malate dehydrogenase, isocitrate dehydrogenase, a-ketoglutarate dehydrogenase
61
Which enzymes release CO2
a-ketoglutarate dehydrogenase, isocitrate dehydrogenase
62
Which enzymes make FADH
Succinate dehydrogenase
63
Which part of TCA makes GTP
Succinyl CoA to succinate
64
Pyruvate dehydrogenase complex
CO2 leaves from a-keto acid a-keto acid decarboxylase transfers the acyl from the keto acid to TPP
65
E1 cofactors
(pyruvate dehydrogenase) TPP
66
E2 cofactors
(Lipoate containing transacyclase) Lipoate CoA
67
E3 coafactors
(dihydrolipoyl dehydrogenase) CoA FAD
68
What is malate dehydrogenase inhibited by
NADH
69
What is isocitrate dehydrogenase and a-ketoglutarate are activated
Ca2+
70
What is isocitrate dehydrogenase and a-ketoglutarate are inhibited by
NADH
71
What is a-ketoglutarate dehydrogenase inhibited by
NADH
72
What is a-ketoglutarate dehydrogenase activated by
Ca2+
73
Which step of PDC participates in all a-ketoacid dehydrogenase complexes?
E3
74
Which step of PDC only participates in pyruvates?
E1 and E2
75
What happens when NADH is too high
It inhibits the cycle and slows it down
76
FA generates acetyl coA via
b-oxidation
77
Which two processes are NOT energetically favorable
Malate to OAA Citrate to isocitrate
78
Which processes are energetically favorable
OAA to citrate Isocitrate to a-ketoglutarate a-ketoglutarate to succinyl CoA Succinyl to succinate
79
Which processes is the MOST energetically favorable
a-ketoglutarate to succinyl CoA
80
What coenzymes does Pyruvate dehydrogenase complex require
NAD+, FAD, lipoic acid, TPP, COA (B1, B2, B3, B5, lipoic acid)
81
When are anaplerotic pathways used
During gluconeogenesis
82
Sources of acetyl CoA
Palmitate, acetoacetate, glucose, pyruvate, alanine, ethanol
83
PDC kinase is inhibited by
ADP Pyruvate
84
PDC kinase is activated by
Acetyl coa, NADH
85
PDC is activated by
pyruvate, NAD+
86
PDC is inactivated by
Acetyl coa, NADH
87
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Biochemistry (13 decks)

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