Citric Acid Cycle Flashcards

1
Q

The “fuel” for the citric acid cycle is

A

Acetyl - CoA

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2
Q

Citric acid cycle produces

A

2 x CO2 (carbon dioxide)
3x NADH
1 x FADH2
1 x GTP (ATP)

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3
Q
  1. In which of the following citric acid cycle reactions does the coenzyme FAD participate?
a.
citrate  to   isocitrate
b.
succinate  to  fumarate
c.
Malate  to  oxaloacetate
d.
more than one correct response
e.
no correct response
A

b.

succinate to fumarate

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4
Q

What is the equivalent amount of NADH and FADH2 in ATP

A

NADH - 2.5 ATP

FADH2 - 1. 5ATP

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5
Q

When a molecule of glucose is completely oxidized through glycolysis and ETC, how many ATP molecules are produced?

A

Approx 30

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6
Q

In the oxidative phosphorylation system the electrons are transported within..

A

the inner membrane of mitochondria along the enzyme system containing flavoprotein –Fe- S protein Q- enzyme- cytochromes

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7
Q

One final product of oxidative phosphorylation is H2O formed from oxygen, electrons and H+ ions. The O2 for this reaction is located in the:

A

Mitochondria

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8
Q

Which reduced co enzymes provide electrons for electron transport?

A

NADH and FADH2

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9
Q

In the final step of electron transport, electrons combine with H+ ions and

A

Oxygen

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10
Q

What is oxidative phosphorylation?

A

electrons flow through the electron transport chain in redox reactions, energy in the electrons goes in ATP

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11
Q

What is the outcome of ETC when it is coupled to oxidative phosphorylation?

A

Water and ATP are formed

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12
Q

Which chemicals link glycolysis and the citric acid cycle to the ETC?

A

membrane complex I & the enzyme Succinate Dehydrogenase which is complex II

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13
Q

Which tends to increase the rate of breathing? An increase in the body’s supply of

a) glycogen
b) ADP
c) inorganic phosphate, HPO42- or Pi

A

b) ADP

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14
Q

Oxidative phosphorylation (OP) differs from substrate level phosphorylation in that ADP is phosphorylated to ATP

a) indirectly when electron and hydrogen carriers use the ETC coupled to OP
b) directly in Glycolysis reaction 7 and 10 and Kreb’s cycle substrate succinyl Co
c) both a) and b) describe differences between OP and substrate level phosphorylation.

A

c) both a) and b) describe differences between OP and substrate level phosphorylation.

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15
Q

How many NADH and FADH2 molecules are produced, respectively, during one turn of the citric acid cycle?

A

Three NADH , one FADH2

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16
Q

At which step in the electron transport chain does O2 participate?

A

Last step

17
Q

ATP synthesis via oxidative phosphorylation depends on the passage of which of the following species through membrane-bound ATP synthase?

A

H+ protons

18
Q

Central driver of cellular respiration

A

Citric acid cycle

19
Q

How is acetyl CoA produced

A

oxidation of pyruvate ( happens just before entering CAC - refer to drawing) which is originally derived from glucose

20
Q

CAC - step 1

A

Acetyl CoA combines with oxaloacetic to produce Citrate

catalysed by citrate synthase

21
Q

CAC - Step 2

A

Isomerisation of Citrate to Isocitrate

catalysed by Aconitase

22
Q

CAC - Step 3

A

Oxidative decarboxylation of Isocitrate

1st redox reaction

NAD+ required - NAD​+ is reduced to form NADH

Catalysed by Isocitrate dehydrogenase

23
Q

CAC - Step 4

A

Oxidative decarboxylation of a-Ketogultarate

2nd redox reaction

NAD+ required - NAD​+ is reduced to form NADH

Catalysed by a 3 enzyme system - a-Ketogultarate dehydrogenase complex

24
Q

CAC - Step 5

A

Formation of Succinate and GTP

Direct Substrate level phosphorylation

Catalysed by Succinyl - CoA synthetase

25
Q

CAC - Step 6

A

Oxidation of Succinate

3rd redox reaction

FAD required - FAD reduced to FADH2 by accepting two hydrogens that succinate loses

Catalysed by the enzyme succinate dehydrogenase

26
Q

CAC - Step 7

A

Hydration of Fumarate to produce L-malate

H2O is added

Catalysed by Fumarase

27
Q

CAC - Step 8

A

Oxidation of L-Malate to produce Oxaloacetate

4th redox reaction

Requires NAD+ - NAD+ reduced to become NADH

Catalysed by Malate dehydrogenase

Oxaloacetate enters the 1st step again to combine with acetyl CoA to form citrate

28
Q

CAC and ETC are common metabolic pathways that take place in the

A

Mitochondria

29
Q

The reactions in the CAC and ETC/Oxidative phosphorylation are the same for all types of food? T/F

A

True.

Carbohydrates, fats and proteins

30
Q

Regulation of CAC =

Citrate synthase (needed for step one of CAC) is inhibited when

A

ATP supplies are high

31
Q

Regulation of CAC =

when ATP levels are low ?

A

Citrate synthase is activated and the CAC speeds up!