Q 5: CHO Metabolism: Glycolysis, the Citric Acid Cycle, and Oxidative Phosphorylation Flashcards

1
Q

What is the primary electron carrier?

A

NAD+

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2
Q

What is the electron acceptor in glycolysis?

A

NAD+

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3
Q

Is glycolysis anaerobic or aerobic?

A

anaerobic

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4
Q

What are the two stages of glycolysis?

A

preparatory - phosphorylation

payoff - oxidation reduction

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5
Q

What cell types in the body receive their primary source of energy through glycolysis?

A

erythrocytes (lack mitochondria)

cancer cells

anaerobic bacteria

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6
Q

What two pathways use ~80% of the same enzymes?

A

glycolysis and gluconeogenesis

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7
Q

What type of rxn does hexokinase initiate on glucose in glycolysis?

A

transfer rxn (moves phosphate from ATP to glucose)

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8
Q

What is the difference between di and bi phosphate?

A

Di-means there are two phosphates connected at one location

Bi-means there are two phosphates connected at different locations

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9
Q

Why is the first ATP of glycolysis important?

A

it keeps glucose in the cell

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10
Q

Where in the cell does glycolysis occur?

A

in the cytoplasm

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11
Q

What do you yield from the payoff phase in glycolysis?

A

2 pyruvate

2 ATP

2 NADH + H+

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12
Q

What inhibits glycolysis?

A

high amounts of citrate (pyruvate –> citrate)

high amounts of ATP

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13
Q

What is the rate limiting enzyme of glycolysis

A

phospho-fructokinase 1

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14
Q

What is the rate limiting step of the pentose phosphate pathway?

A

glucose 6-phosphate –> 6-phosphogluconate

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15
Q

What are the other names for the pentose phosphate pathway?

A

phosphogluconate pathway

hexose monophosphate shunt

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16
Q

What key cells are synthesized in the pentose phosphate pathway?

A

NADPH

Ribose sugars

  • nucleotides
  • ATP
  • FAD
  • Coenzyme A
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17
Q

What inhibits the pentose phosphate pathway?

A

NADPH (which is produced in the pathway)

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18
Q

Why is NADPH necessary/what is it used for?

A

creating FA’s (reductive biosynthesis)

free radical protection

it must be maintained within the cell

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19
Q

Why is fermentation important/why do we need it?

A

we need electron acceptors (it produces 2NAD+)

if you don’t have electron acceptors, glycolysis doesn’t happen

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20
Q

What is the substrate for liver gluconeogenesis?

A

lactate

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21
Q

What is the electron acceptor of the NADH produced in glycolysis?

A

lactate

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22
Q

What happens to lactate after its production?

A

It is shuttled into the blood, taken up by the liver and converted into glucose with ATP within the liver

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23
Q

What rxns occur in the mitochondria?

A

citric acid cycle (starting with pyruvate –> acetyl CoA –> citric acid cylce)

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24
Q

What organelle has a unique genome inherited through the mother?

A

mitochondria (which is found in the egg)

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25
Q

What organelle is involved in apoptosis?

A

mitochondria

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26
Q

What spills out of the mitochondria when it is undergoing apoptosis?

A

cytochrome C

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27
Q

What does cytochrome C from the mitochondria bind to, after spilling out of the mitochondria, in apoptosis?

A

ATP, which will induce Apaf-1 to form an apoptosome which eventually leads to cell death/resorption

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28
Q

What enzyme converts pyruvate to acetyl-CoA?

A

pyruvate dehydrogenase complex

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29
Q

What does the Citric Acid Cycle yield per turn?

A

3 NADH

2 CO2

1 GTP (ATP)

1 FADH2

30
Q

How many turns does one glucose provide in the Citric Acid Cycle?

A

two turns (one glucose is converted into 2 acetyl-CoA)

31
Q

NADH and FADH2 are electron sources for what pathway?

A

oxidative phosphorylation

32
Q

What are the enzymes of the Citric Acid Cycle?

A

citrate synthase

aconitase

aconitase

isocitrate dehydrogenase

a-ketoglutarate dehydrogenase complex

succinyl-CoA synthetase

succinate dehydrogenase

fumarase

malate dehydrogenase

33
Q

Which enzyme in the CAC (citric acid cycle) is also part of the ETC (electron transport chain)?

A

succinate dehydrogenase (electron transport chain complex II)

34
Q

What enzyme is going to reduce an NAD+?

A

dehydrogenase enzyme

35
Q

What steps/enzymes of the CAC produce NADH?

A

isocitrate–>a-ketoglutarate (isocitrate dehydrogenase)

a-ketoglutarate–>succinyl CoA (a-ketoglutarate dehydrogenase complex)

malate–>oxaloacetate (malate dehydrogenase)

36
Q

What step/enzyme of the CAC produces FADH2?

A

succinate–>fumarate (succinate dehydrogenase)

37
Q

Is the NAD+ you have in the mitochondria shared with the NAD+ in the cytoplasm?

A

no

38
Q

Fermentation in the cytoplasm allows for the production of NAD+ for glycolysis, does this occur in the mitochondria to replace depleted NAD+?

A

no

39
Q

What substrates/products of the CAC go back and allosterically inhibit/regulate the CAC?

A

ATP

acetyl-CoA

NADH

FA’s

succinyl-CoA

citrate

40
Q

What does the CAC help synthesize?

A

amino acids

nucleic acids

FA’s

gluconeogenesis

neurotransmitters

hemes

41
Q

What is stage 1 of cellular respiration?

A

acetyl-CoA production

42
Q

what is stage 2 of cellular respiration?

A

acetyl-CoA oxidation

43
Q

what is stage 3 of cellular respiration?

A

electron transfer and oxidative phosphorylation

44
Q

what is stage 3 of cellular respiration?

A

electron transfer and oxidative phosphorylation

45
Q

What is the major fx of the electrons in the electron transport chain?

A

to pump hydrogens from the matrix of the mt into the intermembrane space of the mt

46
Q

Where does the negative charge reside in the mt?

A

in the matrix

47
Q

where does the positive charge reside in the mt?

A

in the intermembrane space

48
Q

In what complex of the ETC is oxygen reduced?

A

complex 4

49
Q

What are the 3 ways that the ETC generates energy?

A

1) electrons are moved into the chain through complex 1 and complex 2
2) H+ ions are pumped from the matrix into the intermembrane space
3) due to the high concentration of H+ ions, they are pumped through ATP synthase back into the matrix

50
Q

What are three common electron carriers transfer electrons BETWEEN/WITHIN the chains and complexes?

A

ubiquinone (semiquinone, ubiquinol)

cytochromes (a, b, and c….C most prominent)

iron-sulfur proteins

51
Q

What molecules transfer electrons TO the chains/complexes?

A

NADH and flavoproteins (FAD, FADH+, FADH2)

52
Q

At what stage/complex are hydrogens pumped into the intermembrane space?

A

Complex 1

53
Q

At what stage/complex is ubiquinone first reduced to semiquinone?

A

complex 1

54
Q

At what stage is ubiquinone fully reduced to ubiquinol?

A

Complex 2

55
Q

At what stage is ubiquinone fully reduced to ubiquinol?

A

Complex 2

56
Q

Where does FA entry into the ETC occur?

A

complex 2

57
Q

What is the Q cycle and where does it occur?

A

occurs at complex 3

involved in the transfer of electrons from ubiquinol to cytochrome c

free electron eventually passed to oxygen to become superoxide

58
Q

What is complex 4 also know as?

A

cytochrome oxidase

59
Q

What happens at complex 4?

A

final step of ETC

oxygen binds with H+ to make water

4H+ pumped back into intermembrane space

oxygen is the final electron acceptor (this is why we breath, so we have enough oxygen to pump 4H+ back into the intermembrane space)

60
Q

What does phosphate translocase (symporter) do?

A

brings Hydrogen phosphate into the matrix (inorganic phosphate for your rxn)

61
Q

How does ADP get into the mt matrix?

A

through the adenine nucleotide translocase (antiporter)

62
Q

How does produced ATP leave the matrix?

A

pumped out via antiporter

63
Q

What is the purpose of the Malate-aspartate shuttle?

A

to get NADH into the matrix of the mt (NADH itself is too big to get into the matrix, so it is shuttled as malate)

64
Q

In which organs does the malate-aspartate shuttle occur?

A

liver, kidney, heart

65
Q

In which organs does the glycerol 3-phosphate shuttle occur?

A

brain and sk. muscle

66
Q

What is the purpose of the glycerol 3-phosphate shuttle?

A

to pass energy via electrons/hydrogens into complex 3

67
Q

What two conditions favor ROS formation?

A

mitochondria not making ATP
-lack of 02 in complex 4 and lack of ADP: leads to backup in ETC

excess NADH

68
Q

What pathway produces the NADPH required to reduce hydrogen peroxide to H2O?

A

pentose phosphate pathway

69
Q

What causes the difference of ATP produced in cellular respiration? (30-32 ATP)

A

The malate-aspartate shuttle produces 32 ATP per molecule of glucose in the liver, kidneys, and heart.

The brain and sk. muscle only generate 30 ATP per molecule of glucose due to the usage of the glycerol 3-phosphate shuttle instead of the malate-aspartate shuttle

70
Q

What does glucose 6-phosphate inhibit?

A

hexokinase (glucose –> glucose 6-phosphate

71
Q

If phoshpofructokinase-1 is inhibited, what happens to glucose 6-phosphate?

A

it goes to the pentose phosphate pathway (PPP) if it’s needed there

if not needed in PPP it is stored as glycogen