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N&E > Z 12. TCA cycle, ET chain and oxidative Phosphorylation > Flashcards

Z 12. TCA cycle, ET chain and oxidative Phosphorylation Flashcards

1
Q

what happens to pyruvate when there is sufficient oxygen?

A

converted to acetyl coenzyme A

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2
Q

what is the role of acetyl coenzyme A?

A

This molecule links glycolysis (cytoplasm) to Krebs/TCA cycle (matrix of mitochondria)

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3
Q

why can red blood cells only perform glycolysis?

A

lack mitochondria

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4
Q

TCA

A

tricarboxylic acid

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5
Q

what is each pyruvic acid converted into?

A

a 2-carbon acetyl group

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6
Q

what happens to the pyruvic acid molecules?

A

Remove one molecule of CO2as a waste product

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7
Q

what else does each pyruvate lose?

A

2 hydrogen atoms

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8
Q

what happens to NAD+?

A

reduced to NADH + H+

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9
Q

what attaches to coenzyme A?

A

Acetyl group attached to coenzyme A to form acetyl coA

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10
Q

what is the net gain from glycolysis and link reaction?

A

2 ATP molecules
4 NADH molecules
2 Acetyl coA molecules

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11
Q

true or false - pyruvate dehydrogenase deficiency is a sex linked disease?

A

true

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12
Q

what is a cause of pyruvate dehydrogenase deficiency?

A

build up of lactic acid in the body.

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13
Q

when do symptoms of pyruvate dehydrogenase deficiency appear?

A

shortly after birth.

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14
Q

what is the most common feature of pyruvate dehydrogenase deficiency?

A

a potentially life-threatening build up of lactic acid (lactic acidosis),

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15
Q

what can the build up of lactic acid cause?

A

nausea, vomiting, severe breathing problems, and an abnormal heartbeat

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16
Q

what are some implications of pyruvate dehydrogenase deficiency?

A

Usually have neurological problems

Most have delayed development of mental abilities and motor skills

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17
Q

why is there lactic acid build up?

A

When pyruvate cannot be converted to acetyl coA, NAD+ is regenerated from NADH by reduction ofpyruvatetolactate by the enzyme lactatedehydrogenase

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18
Q

why do you think neurological problems occur?

A

TCA cycle cannot proceed –> energy deficit remains especially in CNS which way cause brain malformation.

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19
Q

what happens after pyruvate has undergone decarboxylation?

A

it enters the Krebs cycle.

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20
Q

where does the Krebs cycle occur?

A

matrix of the mitochondria

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21
Q

what does the Krebs cycle consist of?

A

Consists of a series of redox and decarboxylation reactions

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22
Q

what do the redox reactions do?

A

transfer energy to NAD+ and FAD

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23
Q

how many ATP molecules are made in the Krebs cycle?

A

12 ATP molecules (24 per glucose)

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24
Q

what molecules are produced form the Krebs cycle?

A

3 NADH

1 FADH2

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25
Q

how is the energy from the glucose stored?

A

the molecules accept the electrons.

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26
Q

what happens with the entry of the acetyl group?

A

Generates the 6 carbon molecule citrate

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27
Q

what happens to the coenzyme A?

A

its recycled.

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28
Q

what is the product of the isomeration of citrate?

A

isocitric acid

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29
Q

what happens in the oxidative decarboxylation?

A

removal of CO2 & formation of NADH & alpha-ketoglutarate

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30
Q

how is succinyl-coA and NADH formed?

A

Oxidative decarboxylation and addition of coA

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31
Q

what happens at substrate level phosphorylation?

A

coA displaced for a phosphate group, which is transferred to GDP and donated to ATP

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32
Q

what is formed at the substrate level phosphorylation?

A

succinate.

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33
Q

what happens in the dehydration step of the Krebs cycle?

A

succinate is oxidised to fumarate by FADH2 formation

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34
Q

what happens in the hydration step of the Krebs cycle?

A

fumarate is converted to malate by addition of water

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35
Q

what is the final step of the Krebs cycle?

A

Dehydrogenation to oxaloacetate & formation of NADH

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36
Q

How many CO2 molecules does Krebs produce from each glucose molecule?

A

4

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37
Q

Which enzyme in Krebs allows for substrate level phosphorylation?

A

Succinyl co-A synthetase

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38
Q

Why do you breathe out more CO2 after exercise?

A

More turns of Krebs cycle

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39
Q

Which enzymes in Krebs reduce NAD?

A

Isocitrate, α-ketoglutarate, malate dehydrogenases

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40
Q

How can the TCA cycle be regulated?

A

Substrate availability
Inhibition by product accumulation
Allosteric inhibition

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41
Q

what is citrate synthase inhibited by?

A

Inhibited by Citrate & ATP

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42
Q

how is Isocitrate dehydrogenase inhibited?

A

Inhibited by NADH & ATP

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43
Q

what activates Isocitrate dehydrogenase?

A

ADP

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44
Q

what inhibits Alpha-ketoglutarate dehydrogenase?

A

NADH & succinyl CoA

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45
Q

what inhibits pyruvate dehydrogenase?

A

NADH and acetyl CoA

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46
Q

what other molecules also regulate pyruvate dehydrogenase?

A

Pyruvate dehydrogenase kinase and phosphatase also regulate the enzyme

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47
Q

what is ATP used for in terms of pyruvate dehydrogenase regulation?

A

ATP is used to phosphorylate a key Ser residue to inactivate the enzyme

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48
Q

what activates the kinase?

A

ATP, NADH, acetyl-coA

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49
Q

what inhibits the kinase?

A

pyruvate.

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50
Q

what are the beginning symptoms of arsenic poisoning?

A

headaches, confusion, severe diarrhoea, and drowsiness

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51
Q

what symptoms develop as the poisoning develops?

A

convulsions and changes in fingernail pigmentation

52
Q

what is the change in fingernail pigmentation due to arsenic poisoning called?

A

leukonychia striata

53
Q

what are the symptoms when arsenic poisoning becomes acute?

A

diarrhoea, vomiting, blood in the urine, cramping muscles, hair loss, stomach pain, and more convulsions

54
Q

what organs are affected by arsenic poisoning?

A

lungs, skin, kidneys, and liver

55
Q

how does arsenic interfere with cellular longevity?

A

allosteric inhibition of an essential metabolic enzyme pyruvate dehydrogenase (PDH) complex

56
Q

oxidation of which of the substrates in the citric acid cycle is not coupled to the production of NADH?

A

succinate

57
Q

Which of the molecules of TCA cycle is used as a precursor for harm biosynthesis (congenital erythropoietic porphyria)?

A

Succinyl co A

58
Q

Which of the molecules of TCA cycle is involved in the formation of Glutamate ?

A

alpha-ketoglutarate.

59
Q

Which of the enzymes is involved in this process of formation of GTP from GDP ?

A

Succinate co-A synthase

60
Q

Which of the intermediates of TCA cycle can be directly converted to phosphoenolpyruvate to trigger the pathway of gluconeogenesis

A

Oxaloacetate

61
Q

what happens as electrons pass through the electron transport chain?

A

exergonic reactions release energy used to form ATP.

62
Q

what is the final electron acceptor?

A

oxygen to form water

63
Q

what are electron carriers?

A

integral membrane proteins in the inner mitochondrial membrane.

64
Q

what happens to NADH dehydrogenase when NADH is oxidised?

A

it is reduced - redox reaction.

65
Q

what happens to the carrier proteins as electrons pass through the ETC?

A

they are oxidised and reduced.

66
Q

what is oxidation?

A

loss of electrons

67
Q

what is reduction?

A

gain of electrons

68
Q

why is oxygen important in the process?

A

without oxygen the redox reaction cannot be repeated.

69
Q

if the redox reaction doesn’t repeat what happens to the ETC?

A

it is left saturated.

70
Q

without oxygen what provides ATP for the ETC?

A

glycolysis

71
Q

what is a poison that blocks the ETC?

A

Cyanide

72
Q

what is cyanide?

A

non-competitive inhibitor to cytochrome oxidase.

73
Q

how does Cyanide work?

A

blocks the donation of electrons and hydrogen to oxygen, halting aerobic respiration entirely.

74
Q

what is the benefit of the cristae?

A

they maximise the surface area of the membrane this increases the rate of ATP production

75
Q

what is the first protein in the ETC?

A

NADH dehydrogenase

76
Q

what does the oxidation off NADH produce?

A

proton (H+), and NAD+ and 2 electrons

77
Q

what happens to the electrons produced from the oxidation of NADH?

A

bind to NADH dehydrogenase.

78
Q

what happens to the electrons as they move through the ETC?

A

lose energy

79
Q

what happens to the energy that is lost?

A

some is used to pump H+ ions from the matrix into the intermembrane space, the rest is lost as heat.

80
Q

why does a concentration gradient form?

A

the inner mitochondrial membrane is impermeable to H+ ions.

81
Q

how do H+ ions travel into the matrix?

A

they move down their concentration gradient using protein channels.

82
Q

what are the protein channels associated with?

A

enzyme ATP synthase

83
Q

what does ATP synthase do?

A

phosphorylates one ADP for each H+ ion that passes through.

84
Q

what is chemiosmosis?

A

the use of energy in a chemical gradient to generate ATP by the flow of hydrogen ions through ATP synthase.

85
Q

what is the final protein in the ETC?

A

cytochrome oxidase.

86
Q

what does cytochrome oxidase do?

A

donates the electron pair to an oxygen atom.

87
Q

what happens due to the donation of electrons to the oxygen molecules?

A

releases enough energy to pump other H+ ion across the membrane - can be used to regenerate another molecule of ATP.

88
Q

what other molecule is also oxidised by the ETC?

A

FADH2

89
Q

which protein of the ETC does FADH2 interact with?

A

the second protein.

90
Q

what does FADH2 interaction with the second protein mean?

A

less H+ is pumped into the intermembrane space, so less ATP is regenerated.

91
Q

what are flavin mononucleotides (FMN)

A

flavoprotein (protein with a nucleic acid derivative of riboflavin- vitamin B2)

92
Q

what are cytochromes?

A

proteins with an iron containing group capable of existing in a reduced (Fe2+) and oxidised (Fe3+) form.

93
Q

some examples of cytochromes?

A

cyt b, cyt c1, cyt c, cyt a, cyt a3

94
Q

what forms the electron transfer centre?

A

Iron-sulfur centres (Fe-S) contain 2 or 4 iron atoms bound to sulfur atoms

95
Q

true or false copper atoms participate in the electron transfer?

A

true - copper atoms bound to 2 proteins participate in the transfer.

96
Q

what is coenzyme Q?

A

non-protein carrier in the lipid bilayer

97
Q

cytochrome c reductase goes through which electron carriers?

A

Cytochrome b-

Fe-S centre- cytochrome c1 complex

98
Q

cytochrome oxidase goes through which electron carriers?

A

Cu -Cyt a – Cyt a3

99
Q

what happens to the electrons which pass from NADH to NADH reductase?

A

The electrons are accepted by FMN, and then passed to the iron atoms of the FeS clusters, where Fe3+ changes to Fe2+

100
Q

what does ubiquinone (coenzyme Q) do?

A

shuttles the electrons to cytochrome reductase (cytochrome b to FeS centres)

101
Q

what shuttles the electrons to cytochrome oxidase?

A

cytochrome c

102
Q

what happens at cytochrome oxidase?

A

Cu2+ is converted to Cu+

103
Q

what is the final electron carrier?

A

cytochrome c oxidase

104
Q

what does cytochrome c oxidase do?

A

passes 4 electrons to molecular oxygen to form 2 molecules of water

105
Q

how much ATP is generated from each glucose molecule in the electron transfers?

A

The various electron transfers in the ETC generate either 32 or 34 ATP molecules from each molecule of glucose

106
Q

how is the ATP generation split between molecules?

A

Either 28 or 30 from the 10 molecules of NADH + H+ and 2 from each of the 2 molecules of FADH2

107
Q

what is different about NADH made in glycolysis?

A

cannot enter the mitochondria

108
Q

what do the NADH that are made in glycolysis do?

A

They donate electrons to either the malate or glycerol phosphate shuttle

109
Q

what organs use the malate shuttle?

A

liver, kidneys and heart.

110
Q

how many ATP molecules result from the malate shuttle?

A

3

111
Q

what shuttle does the rest of the body use?

A

glycerol phosphate

112
Q

how many ATP molecules result from the glycerol phosphate shuttle?

A

2

113
Q

what molecule is used as a H acceptor in the glycerol phosphate shuttle?

A

FAD

114
Q

how many ATPs are generated from substrate level phosphorylation in glycolysis?

A

2

115
Q

how many ATPs are generated from substrate level phosphorylation in the Krebs cycle?

A

2

116
Q

what is the first step in the process of NAD+ regeneration in aerobic glycolysis?

A

NADH from the cytosol gives up its two electrons and Hydrogen to Dihydroxyacetone phosphate (DHAP) forming Glycerol 3-phosphate.

117
Q

what does glycerol 3-phosphate do?

A

binds to inner membrane bound glycerol 3-phosphate dehydrogenase (G3PDH)

118
Q

what does G3PDH have attached to it?

A

a FAD prosthetic group

119
Q

where does glycerol 3-phosphate transfer its electrons to?

A

the FAD prosthetic group.

120
Q

what is the role of ubiquinone in the regeneration of NAD+?

A

binds the FAD group, takes the electrons away, shuttling the electrons into the electron transport chain at cytochrome reductase

121
Q

true or false - cytosolic NADH electrons is equivalent to a mitochondria generated FAD electrons?

A

true

122
Q

what happens to glycerol 3-phosphate in the process of giving its electrons to G3PDH?

A

re-oxidses to forms DHAP - the cycle can begin again.

123
Q

how many ATPs are produced at the oxidative phosphorylation stage of glycolysis?

A

4-6

124
Q

how many ATPs are produced during the link reaction (oxidative phosphorylation)?

A

6

125
Q

how many ATPs are produced during the oxidation of succinyl-CoA to succinic acid?

A

2 GTPs that are converted to ATPs.

126
Q

how much ATP is produced during the production of 6 NADH + 6H+?

A

18 ATPs

127
Q

how much ATP is produced during the production 2 FAD2?

A

4 ATPs

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