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biochem > Citric Acid Cycle > Flashcards

Citric Acid Cycle Flashcards

1
Q

What is the citric acid cycle?

A

It is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

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2
Q

What is the function of the citric acid cycle?

A

The function of the citric acid cycle is to harvest high-energy electrons from carbon fuels.

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3
Q

What is stage 1 of respiration?

A

carbon from metabolic fuels (CHO, fats and proteins) is incorporated into acetyl-CoA during aerobic respiration

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4
Q

What is stage 2 of respiration?

A

the Krebs cycle oxidizes acetyl-CoA to produce CO2, reduced electron carriers, and a small amount of ATP

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5
Q

What is stage 3 of respiration?

A

the reduced electron carriers (NADH, FADH2) are re-oxidized, providing energy for the synthesis of additional ATP

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6
Q

When we say electrons, we are talking about ________.

A

energy

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7
Q

How are electrons captured?

A

Usually by producing NADH and FADH2

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8
Q

NADH and FADH2 getting transported to the mitochondria is which stage?

A

stage 2

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9
Q

Where does the citric acid cycle take place?

A

mitochondrial matrix

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10
Q

The final electron acceptor of electrons is _______.

A

oxygen

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11
Q

Where does oxidative phosphorylation occur?

A

In the inner mitochondrial membrane

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12
Q

Do adults have brown adipose tissue?

A

no

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13
Q

The _______ is impermeable to ions and most other compounds.

A

inner mitochondrial membrane

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14
Q

The chemical energy used for most cellular process is carried by?

A

ATP

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15
Q

The Bonds between the phosphate groups in ATP are very [high/low] energy

A

high

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16
Q

When a phosphate group is [added/removed], energy is released.

A

removed

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17
Q

One way carbohydrate energy is used by organisms is through the process of __________.

A

cellular respiration

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18
Q

The more phosphate groups, the [less/more] energy.

A

more

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19
Q

Order these from lowest energy to highest energy: ADP, ATP, AMP.

A
  1. AMP
  2. ADP
  3. ATP
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20
Q

Where can we find substrate-level phosphorylation occurring?

A

during Glycolysis and the Kreb’s Cycle

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21
Q

__________ involves the physical addition of a free phosphate to ADP to form ATP.

A

substrate-level phosphorylation

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22
Q

Where can we find oxidative phosphorylation occurring?

A

electron transport chain

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23
Q

What happens in the electron transport chain?

A

ATP is synthesized indirectly from the creation of a proton gradient and the movement of these protons back across the membrane through the protein channel, ATP synthase

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24
Q

Pyruvate freely diffuses through the __________ through the channels formed by trans-membrane proteins called ______.

A

outer membrane of mitochondria; porins

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25
Q

What types of proteins are porins?

A

transmembrane proteins

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26
Q

What is pyruvate translocase?

A

protein embedded into the inner membrane

27
Q

Function of pyruvate translocase?

A

it transports pyruvate from the inter-membrane space into the matrix

28
Q

Where is pyruvate produced?

A

In the cytoplasm

29
Q

What happens to the pyruvate for it to enter the TCA cycle?

A

It has to be converted into Acetyl-CoA

30
Q

How can the pyruvate pass through the impermeable inner mitochondrial membrane?

A

By pyruvate translocase

31
Q

Where is pyruvate converted into Acetyl-CoA?

A

In the matrix

32
Q

Pyruvate oxidation to acetyl-CoA is catalyzed by?

A

pyruvate dehydrogenase complex (PDH complex)

33
Q

Pyruvate oxidation is an oxidative ______ process.

A

decarboxylation

34
Q

Pyruvate oxidation is a [irreversible/reversible] reaction.

A

irreversible

35
Q

Pyruvate oxidation involves how many coenzymes?

A

5 coenzymes

36
Q

Pyruvate oxidation involves how many enzymes?

A

3 enzymes

37
Q

Pyruvate dehydrogenase is located where in the cell?

A

In the matrix of the mitochondria

38
Q

Name the coenzymes involved in pyruvate oxidation

A 
Thiamine pyrophosphate (TPP)
FAD+
NAD+
Lipoamide
HS-CoA
39
Q

Name the vitamins involved in pyruvate oxidation

A 
B1 - thiamine
B2 - riboflavin
B3 - pantothenic acid
B5 - nicotinamide
Lipoic acid
40
Q

Which step will produce ATP?

A

The conversion of Succinyl CoA to Succinate using an enzyme Succinyl CoA synthase. (step 4)

41
Q

What is equivalent to ATP?

A

GTP

42
Q

Which step will produce FADH2?

A

The conversion of Succinate into Fumarate.

43
Q

Which steps would involve the generation of NADH in the TCA cycle?

A

3 steps:
Isocitrate dehydrogenase
α-Ketoglutarate dehydrogenase complex
Malate dehydrogenase

44
Q

How much energy do we get per NADH?

A

3 ATP

45
Q

How much energy do we get per FADH2?

A

2 ATP

46
Q

Citrate is formed from _________.

A

acetyl CoA and oxaloacetate

47
Q

What is the only cycle reaction with C-C bond formation?

A

citrate synthase

48
Q

Elimination of H2O from citrate to form C=C bond of ___________.

A

cis-aconitate

49
Q

Stereospecific addition of H2O to cis-aconitate forms?

A

isocitrate

50
Q

How many oxidation-reduction reactions take place in the citric acid cycle?

A

4

51
Q

Oxalosuccinate is decarboxylated to _________.

A

a-ketoglutarate

52
Q

Oxidative decarboxylation of isocitrate to ________.

A

a-ketoglutarate

53
Q

Succinyl-CoA Synthetase catalyzes what type of reaction?

A

Substrate level phosphorylation reaction

54
Q

What is the succinate dehydrogenase complex?

A

Complex of several polypeptides, an FAD prosthetic group and iron-sulfur clusters.

55
Q

Where is the succinate dehydrogenase complex embedded?

A

in the inner mitochondrial membrane

56
Q

Stereospecific trans addition of water to the double bond of ______ forms L-malate

A

fumarate

57
Q

Is the citric acid cycle anabolic or catabolic?

A

amphibolic (both catabolic and anabolic)

58
Q

The TCA cycle yields energy in the form of?

A

ATP

59
Q

The TCA cycle yields reducing power in the form of?

A

NADH and FADH2

60
Q

Is regulation of the TCA cycle considered a step of the TCA cycle?

A

no

61
Q

The TCA cycle is regulated by?

A

(1) Allosteric modulators (Alteration of the activity of an enzyme by means of a conformational change induced by a different molecule).
(2) Covalent modification of cycle enzymes (Regulation by phosphorylation/ dephosphorylation)
(3) Supply of acetyl CoA (pyruvate dehydrogenase complex)

62
Q

“Can I Keep Selling Substances For Money, Officer?”

stands for?

A 
Can = Citrate
I = Isocitrate
Keep = Ketoglutarate
Selling = Succinyl CoA
Substances = Succinate
For = Fumarate
Money = Malate
Officer = Oxaloacetate
63
Q

For every Acetyl CoA, how many ATP molecules are generated?

A

10

biochem (8 decks)

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