Kreb's Cycle Flashcards

1
Q

What are the other two names for the Kreb’s cycle?

A

TCA cycle
Citric acid cycle

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2
Q

What can enter the Kreb’s cycle?

A

Fatty acids, glucose as pyruvate, amino acids

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3
Q

What is the purpose of the Kreb’s cycle?

A

Biosynthesis and energy production

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4
Q

What are the products of the energy production in Kreb’s cycle?

A

3 NADH, FADH2, 2 CO2, GTP

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5
Q

What are the products of the biosynthesis in Kreb’s cycle?

A

Glucose, fatty acids, non-essential amino acids, succinyl CoA precursor for porphyrins

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6
Q

What stimulates fatty acid production?

A

High carb diet with no exercise

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7
Q

What two amino acids are the easiest to make?

A

Aspartate and glutamate

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8
Q

What intermediate is required to make heme?

A

Succinyl CoA

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9
Q

What needs heme?

A

Hemoglobin, cytochromes

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10
Q

What must the Kreb’s cycle be paired with to make energy?

A

Electron transport chain

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11
Q

What is the starting molecule of Kreb’s cycle?

A

Acetyl CoA

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12
Q

What is the first equation of the Kreb’s cycle?

A

Oxaloacetate + acetyle CoA -> citrate

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13
Q

What two things can leave the Kreb’s cycle?

A

Citrate and malate

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14
Q

How do carbs enter the Kreb’s cycle?

A

Glycolysis

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15
Q

What do carbs enter the Kreb’s cycle as?

A

Pyruvate

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16
Q

What is the pre-Kreb’s step for pyruvate?

A

Pyruvate to acetyl CoA

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17
Q

What coenzymes are needed for pyruvate to acetyl CoA?

A

B1, B2, B3, B5/CoA, lipoic acid

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18
Q

How do fatty acids enter the Kreb’s cycle?

A

Beta oxidation into acetyl CoA

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19
Q

What is the purpose of the aconitase enzyme in step two?

A

No glucose production of fat

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20
Q

What two minerals support the function of the aconitase enzyme?

A

Iron and sulfur

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21
Q

What foods are rich in iron?

A

Spinach, red meat, raisins

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22
Q

What foods are rich in sulfur?

A

Cruciferous vegetables, eggs, asparagus, onions

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23
Q

What is the allosteric enzyme in the TCA cycle?

A

Isocitrate dehydrogenase

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24
Q

What two compounds, if they build up, inhibit isocitrate dehydrogenase?

A

NADH and ATP

25
Q

What is the name of the enzyme that uses all the same co-enzymes as pyruvate dehydrogenase?

A

Alpha ketoglutarate dehydrogenase

26
Q

Name a compound that can be made from succinyl coA

A

Heme

27
Q

Name the enzyme that converts pyruvate to OAA

A

Pyruvate carboxylase

28
Q

Name the high energy compound made in the step succinyl CoA -> succinate

A

GTP

29
Q

What complex in the cytochrome chain contains the enzyme succinate dehydrogenase?

A

Complex II

30
Q

What is the significance of succinate dehydrogenase?

A

Succinate dehydrogenase anchors Kreb’s to the inner mitochondrial matrix

31
Q

What does succinate dehydrogenase allow for?

A

Kreb’s to couple to the electron transport chain

32
Q

What is the location in the mitochondria of most Kreb’s cycle enzymes?

A

Mitochondrial matrix

33
Q

What is the coenzyme for the enzyme fumarase?

A

Water

34
Q

What is the name of the enzyme that converts malate to OAA?

A

Malate dehydrogenase

35
Q

What coenzyme is needed for malate dehydrogenase to convert malate to OAA?

A

NAD+

36
Q

What do ketogenic compounds enter Kreb’s cycle as?

A

Acetyl CoA

37
Q

Name the ketogenic only compounds

A

Fatty acids, lysine, leucine

38
Q

Name the amino acids that are both ketogenic and gluconeogenic

A

Phenylalanine, isoleucine, tyrosine, tryptophan

39
Q

Where do gluconeogenic amino acids enter the Kreb’s cycle?

A

Other intermediates

40
Q

What amino acids enter as pyruvate?

A

Alanine, glycine, cysteine, serine, threonine, tryptophan

41
Q

What amino acids enter as alpha ketoglutarate?

A

Histidine, arginine, proline, glutamate, glutamine

42
Q

What enzyme is used for the amino acids entering as alpha ketoglutarate?

A

SGPT

43
Q

What amino acids enter as succinyl CoA?

A

Valine, isoleucine, methionine

44
Q

What amino acids enter as fumarate?

A

Phenylalanine, aspartate, tyrosine

45
Q

What amino acids enter as oxaloacetate?

A

Aspartate, asparagine

46
Q

What enzyme is used for amino acids entering as oxaloacetate?

A

SGOT/aspartate transaminase

47
Q

What is the energy yield for 1 acetyl CoA when Kreb’s and ETC are combined without accounting for heat?

A

12

48
Q

What is the energy yield for 1 acetyl CoA when Kreb’s and ETC are combined with accounting for heat?

A

10

49
Q

What is the total energy yield for aerobic glycolysis (depending on shuttle) without accounting for heat?

A

36 or 38

50
Q

What is the total energy yield for aerobic glycolysis (depending on shuttle) with accounting for heat?

A

30 or 32

51
Q

What three substances decrease the action of pyruvate dehydrogenase by end product inhibition?

A

NADH, acetyl CoA, ATP

52
Q

What type of diet increases the concentration of OAA?

A

High carbohydrates

53
Q

What is the impact of high carbohydrates in the diet on the rate of the TCA cycle?

A

Increases the rate

54
Q

Why does a high alcohol diet slow the rate of the Kreb’s cycle?

A

Lots of NADH with alcohol dehydrogenase

55
Q

What is the impact of high levels of citric acid on glycolysis?

A

Shuts off phosphofructokinase

56
Q

What pathway is turned on by high levels of citrate in the cytoplasm

A

Fat synthesis

57
Q

What is the impact of lack of exercise on the Kreb’s cycle?

A

Increases ATP which turns off the cycle

58
Q

What cycle in the liver is connected with the Kreb’s cycle?

A

Urea cycle