Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MSK Week 1 > TCA Cycle > Flashcards

TCA Cycle Flashcards

1
Q

What is so special about the TCA cycle?

A

Major energy producing pathway in the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where does the TCA cycle occur?

A

Mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In what form does food product reach the TCA cycle?

A

Acetyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the general idea of the CA cycle?

A

Take Acetyl CoA and oxidize it to make carbon dioxide and water in order to make energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where are all of the enzymes we need for the TCA cycle?

A

All the enzymes of the TCA cycle are in the mitochondrial matrix except succinate dehydrogenase, which is in the inner mitochondrial matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Acetyl CoA and ozaloacetate condense to form what?

A

Citrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What enzyme condenses acetyl-CoA and oxaloacetate to make citrate?

A

Citrate synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Citrate is isomerized to what?

A

Isocitrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What enzyme turns citrate to isocitrate?

A

Aconitase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Isocitrate is oxidized to what?

A

Alpha ketoglutarate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What two step process is involved in turning isocitrate to alpha ketoglutarate?

A

Oxidation
Decarboxylation

(CO2 is produced and the electrons are passed to NAD+ to form NADH and H+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What enzyme turns isocitrate to alpha ketoglutarate?

A

Isocitrate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What activates isocitrate dehydrogenase? Inhibits it?

A

This key regulatory enzyme of the TCA cycle is allosterically activated by ADP and inhibited by NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to alpha ketoglutarate once it is made?

A

converted to succinyl-CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Alpha ketoglutarate to Succinyl-CoA is an example of what kind of reaction?

A

oxidative decarboxylation reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What enzyme turns alpha-ketoglutarate to succinyl CoA?

A

α-ketoglutarate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What cofactors are required for α-ketoglutarate dehydrogenase?

A

This enzyme requires five cofactors: thiamine pyrophosphate, lipoic acid, CoASH, FAD, and NAD+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens to succinyl CoA?

A

cleaved to succinate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do we get energy from the succinyl CoA to succinate reaction?

A

Cleavage of the high-energy thioester bond of succinyl-CoA provides energy for the substrate-level phosphorylation of GDP to GTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What enzyme cleaves succinyl CoA to succinate?

A

succinate thiokinase aka succinyl-CoA synthetase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens to succinate?

A

oxidized to fumarate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What electron carrier is involved at the step where sucinate becomes fumarate?

A

succinate transfers two hydrogens together with their electrons to FAD, which forms FADH2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What enzyme oxidizes succinate to fumarate?

A

succinate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where does the succinate to fumarate rxn occur?

A

Inner mitochondrial membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens to fumarate?

A

Converted to malate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What enzyme turns fumarate to malate?

A

Fumarase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How does fumarase turn fumarate to malate?

A

Adds water across the double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What happens to malate?

A

Oxidized to regenerate oxaloacetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What oxidizes malate to oxaloacetate?

A

Malate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What enzyme carrier is involved with the malate dehydrogenase rxn?

A

two hydrogens along with their electrons are passed to NAD+, producing NADH and H+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How much ATP per NADH?

A

2.5 ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How much ATP per FADH2

A

1.5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How much ATP per turn of the TCA cycle?

A

1 mole of acetyl CoA gives us 10 moles of ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What happens during fasting?

A

Intermediates of the TCA cycle are utilized in the fasting state in the liver for the production of glucose and in the fed state for the synthesis of fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are anaplerotic reactions?

A

Anaplerotic reactions replenish intermediates of the TCA cycle as they are removed for the synthesis of glucose, fatty acids, amino acids, or other compounds

36
Q

One of the most important anaplerotic reactions?

A

Carboxylation of pyruvate to oxaloacetate

37
Q

What enzyme carboxylates pyruvate to oxaloacetate?

A

pyruvate carboxylase

38
Q

What cofactor does pyruvate carboxylase need?

39
Q

What activates the enzyme pyruvate carboxylase besides its cofactor biotin?

A

Acetyl-CoA

40
Q

Where is pyruvate carboxylase found?

A

Liver
Brain
Adipose Tissue

41
Q

What reactions do amino acids do to produce TCA intermediates?

A

Anaplerotic reactions

42
Q

What amino acids form glutamate?

A

Glutamine, proline, arginine and histidine

43
Q

What amino acid forms aspartate?

A

Asparagine

44
Q

What becomes oxaloacetate?

45
Q

Name of the reaction type that turns aspartate to oxaloacetate

A

Transamination

46
Q

How is Succinyl CoA formed?

A

Propionyl-CoA gets converted to methylmalonyl-CoA and subsequently to Succinyl-CoA

47
Q

Formation of propionyl CoA

A

You need Valine, isoleucine, methionine and threonine

48
Q

What amino acids make fumarate?

A

Phenylalanine, tyrosine, and aspartate

49
Q

What pathway slows down the TCA cycle?

A

Gluconeogenesis, which uses intermediates of the TCAcycle

50
Q

What happens to the TCA cycle as glucose is synthesized?

A

malate or oxaloacetate is removed from the TCA cycle and replenished by anaplerotic reactions

51
Q

Pyruvate is formed by what compounds?

A

Lactate or alanine

52
Q

What product of the TCA cycle is important for fatty acid synthesis?

53
Q

What catalyzes the anaplerotic reactions that replenish the TCA cycle intermediates?

A

Pyruvate Carboxylase

54
Q

How can we get amino acids from glucose via the oxaloacetate pathway?

A

Glucose is converted to pyruvate, which forms oxaloacetate, which by transamination forms aspartate and, subsequently, asparagine

55
Q

How can we get amino acids from glucose via the oxaloacetate and acetyl CoA pathway?

A

Glucose is converted to pyruvate, which forms both oxaloacetate and acetyl-CoA, which condense, forming citrate. Citrate forms isocitrate and then α-ketoglutarate, from which glutamate, glutamine, proline, and arginine are produced

56
Q

What accelerates the ETC?

A

When ADP levels are high relative to ATP the reactions of the electron transport chain are accelerated.

57
Q

What speeds up the TCA cycle?

A

NADH is rapidly oxidized by the ETC; consequently, the TCA cycle speeds up

58
Q

What slows down the ETC?

A

When the concentration of ATP is high the electron transport chain slows down

59
Q

What slows down the TCA cycle?

A

When the concentration of ATP is high the electron transport chain slows down, NADH builds up, and consequently the TCA cycle is inhibited

60
Q

How, specifically, does the TCA cycle slow down (this is very involved, but think about the process)

A

NADH allosterically inhibits isocitrate dehydrogenase. Isocitrate accumulates, and because the aconitase equilibrium favors citrate, the concentration of citrate rises. Citrate inhibits citrate synthase, the first enzyme of the cycle.

61
Q

What happens to oxaloacetate when NADH is high?

A

Oxaloacetate is converted to malate when NADH is high and, therefore, less substrate (OAA) is available for the citrate synthase reaction

62
Q

What reactions are NAD used in?

A

isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and malate dehydrogenase reactions

63
Q

What is niacin important for?

A

Niacin is used for the synthesis of the nicotinamide portion of NAD

64
Q

What is important for the production of FAD?

A

Riboflavin

65
Q

What is thiamine important for?

A

the synthesis of thiamine pyrophosphate

66
Q

Importance of Pantothenate?

A

synthesis of CoASH

67
Q

Effects of low Vitamin A

A

Night blindness and xerophthalmia

68
Q

Effects of low Vitamin D

A

Inadequate bone mineralization, rickets in children

69
Q

Effects of low Vitamin E

A

Reproductive failure, muscular dystrophy, neurologic abnormalities

70
Q

Effects of low Vitamin K

A

Defective blood coagulation

71
Q

Effects of low Vitamin C

72
Q

Effects of low thiamine?

73
Q

Effects of low riboflavin?

A

Oral-buccal cavity lesions

74
Q

Effects of low niacin?

A

Pellagra (diarrhea, dermatitis, dementia, death)

75
Q

Effects of low Vitamin B6

A

Convulsions, dermatitis, anemia

76
Q

Effects of low Folate

A

Megaloblastic Anemia

77
Q

Effects of low Vitamin B12?

A

Megaloblastic Anemia and neurological symptoms

78
Q

Effects of low biotin

A

Anorexia, nausea, vomitis, glossitis, alopecia

79
Q

Effects of low pantothenic acid

A

Listlessness, fatigue, burning feet syndrome

80
Q

How do Carbons from glucose enter the TCA cycle?

A

In order for carbons from glucose to enter the TCA cycle, glucose is first converted to pyruvate by glycolysis, then pyruvate forms acetyl-CoA

81
Q

How is acetyl CoA formed?

A

Pyruvate dehydrogenase catalyzes the oxidative decarboxylation of pyruvate, forming acetyl-CoA

82
Q

Where is pyruvate dehydrogenase?

A

Pyruvate dehydrogenase, a multienzyme complex located exclusively in the mitochondrial matrix

83
Q

What is similar between pyruvate dehydrogenase and alpha ketoglutarate?

A

They need the same 5 components

84
Q

What is different between pyruvate dehydrogenase and alpha ketoglutarate?

A

In contrast to α-ketoglutarate dehydrogenase, a pyruvate dehydrogenase exists in a phosphorylated (inactive) form and a dephosphorylated (active) form

85
Q

How is pyruvate decarboxylase deactivated?

A

CoASH and NAD+. Can also be inactivated by ADP

86
Q

What activates the pyruvate decarboxylase?

A

The products of the pyruvate dehydrogenase reactions, acetyl-CoA and NADH. It is activated specifically by a phosphatase

87
Q

How is pyruvate decarboxylase controlled, generally?

A

When the concentration of substrates is high, the dehydrogenase is active, and pyruvate is converted to acetyl-CoA. When the concentration of products is high, the dehydrogenase is relatively inactive

MSK Week 1 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions