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BIO 2 > CELLULAR RESPIRATION (LECTURE 5) > Flashcards

CELLULAR RESPIRATION (LECTURE 5) Flashcards

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1
Q

Cellular respiration is what type of a reaction?

A

It is a redox reaction where glucose is oxidized? not sure didnt fill this out

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2
Q

Cellular respiration is essentially the opposite of ____.

A

Cellular respiration is essentially the opposite of photosynthesis.

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3
Q

What is being oxidized in cellular respiration? Write a simple chemical equation of this oxidation.

A

Glucose is being oxidized: C6H12O6 –> 6 CO2

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4
Q

What is being reduced in cellular respiration? Provide a chemical formula.

A

Oxygen is being reduced: 6O2 –> 12 H2O

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5
Q

What are the electron carriers that participate in cellular respiration?

A

NADH and FADH2.

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6
Q

Describe the path of electrons through cellular respiration. (source, shuttles, final use).

A

Through glycolysis, pyruvate oxidation and the citric acid cycle, e- are stripped from glucose and transferred to NAD+ and FAD. The now NADH and FADH2 carry the electron to the electron transport chain (ETC) to make ATP by oxidative phosphorylation.

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7
Q

What are the two ways to produce ATP within cellular respiration?

A

By substrate-level phosphorylation and by oxidative phosphorylation.

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8
Q

Describe the production of ATP by substrate-level phosphorylation. Where in cellular respiration does this occur?

A

An enzyme catalyzes the transfer of a phosphate group to ADP from a substrate. This occurs in glycolysis and the Krebs cycle.

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9
Q

Describe the production of ATP by oxidative phosphorylation. Where in cellular respiration does this occur?

A

Chemiosmosis powers the production of ATP by ATP-synthase. This occurs in the electron transport chain.

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10
Q

Between substrate-level phosphorylation and oxidative phosphorylation, which method resembles photophosphorylation the most?

A

Oxidative phosphorylation resembles photophosphorylation the most.

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11
Q

What are the 4 components (reactions) of cellular respiration?

A

Glycolysis, pyruvate oxidation, the Krebs cycle (or citric acid cycle) and the electron transport chain.

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12
Q

What is the overall reaction for glycolysis?

A

Glucose –> 2 pyruvate + 2 NADH + 2 ATP

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13
Q

Glycolysis produces ATP by which method?

A

Glycolysis produces ATP by substrate-level phosphorylation.

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14
Q

What are the two phases of glycolysis?

A

The energy requiring phase and the energy producing phase.

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15
Q

Describe the energy requiring phase of glycolysis.

A

Glucose turns to glucose-6-phosphate (uses 1 ATP), which then turns to fructose-6-phosphate, which then turns to fructose 1,6,bisphosphate (uses 1 ATP, catalyzed by PFK) which then turns to two G3P molecules.

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16
Q

Describe the energy producing phase of glycolysis.

A

Two G3P molecules turn to (two) 1,3 bisphosphoglycerate (this produces two NADH), which then turns to 3-phosphoglycerate (produces 2 ATP), which then turns to phosphoenolpyruvate (or PEP), which then turns to pyruvate (produces 2 ATP).

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17
Q

Where does glycolysis occur?

A

Glycolysis occurs in the cytosol (outside the mitochondria).

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18
Q

What is the overall reaction of pyruvate oxidation?

A

2 pyruvate (+ CoA) –> 2 Acetyl-CoA + 2 NADH + 2 CO2

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19
Q

Describe pyruvate oxidation: where does the pyruvate come from? Where does it occur? What is the primary reaction? What are the products of pyruvate oxidation?

A

Pyruvate is transported into the mitochondrial matrix (after being produced through glycolysis in the cytosol) and then oxidized to acetyl-CoA. From 2 pyruvate molecules and whatever’s left of glucose, pyruvate oxidation produces 2 Acetyl-Coa, 2 NADH and 2 CO2.

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20
Q

What is being oxidized in the Krebs cycle?

A

Acetyl-CoA is oxidized to CO2.

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21
Q

Where does the Krebs cycle occur?

A

In the mitochondrial matrix.

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22
Q

What is the overall reaction equation for the Krebs cycle?

A

2 Acetyl-CoA –> 6 NADH + 2 FADH2 + 2 ATP + 4 CO2

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23
Q

What sentence can be used to remember the steps of the Krebs cycle?

A

“I am so sorry for making oatmeal cookies”

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24
Q

What are the steps of the Krebs cycle and what is produced at each step? (starting at isocitrate)

A

Isocitrate -(1 NADH; 1 CO2)- a-ketoglutarate -(1 NADH; 1 CO2)- Succinyl CoA -(1 ATP via GTP)- Succinate -(1 FADH2)- Fumarate – Malate -(1 NADH)- Oxaloacetate -(Acetyl-CoA becomes CoA)- Citrate.

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25
Q

The Krebs cycle runs how many times per glucose molecule? Per Acetyl-CoA molecule?

A

The Krebs cycle runs twice per glucose molecule and thus once per acetyl-CoA molecule.

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26
Q

What is produced by the Krebs cycle (net production) per glucose molecule (2 runs)?

A

6 NADH, 2 FADH2, 2 ATP & 4 CO2.

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27
Q

By what type of phosphorylation is ATP produced in the Krebs cycle?

A

In the Krebs cycle, ATP is produced by substrate-level phosphorylation.

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28
Q

What is the overall reaction equation for the electron transport chain (4th component of cellular respiration)?

A

10 NADH + 2 FADH2 + 6 O2 –> 28 ATP + 12 H2O

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29
Q

Where is the ETC (used for cellular respiration) located?

A

It is embedded in the inner mitochondrial membrane (IMM).

30
Q

What are the components of the ETC (used for cellular respiration)?

A

3 enzymes (complexes i, iii and iv; they contain cofactors that act as e- carriers). 2 mobile e- carriers (coenzyme Q and cytochrome C). Complex ii (shuttles e- from FADH2 to coenzyme Q).

31
Q

Describe the energy levels of e- passing through the electron transport chain (cellular respiration). How is this related to oxidative phosphorylation?

A

e- move through the ETC from high energy to low energy (spontaneous). Energy released is used to pump protons into the intermembrane space to generate a proton gradient (pumping protons is non-spontaneous).

32
Q

ATP produced in the ETC (cellular respiration) is produced by which type of phosphorylation?

A

By oxidative phosphorylation.

33
Q

Describe the role of complex I (ETC). (2)

A

Complex I receives e- form NADH and pumps protons from the matrix into the intermembrane space.

34
Q

Describe the role of coenzyme Q (ubiquinone). (3)

A

Coenzyme Q receives e- from complex I or FADH2 (via complex II) and moves in the lipid bilayer (it is lipid soluble).

35
Q

Describe the role of complex III. (3)

A

Receives e- from coenzyme Q, pumps protons from matrix into intermembrane space and contains cytochromes (which are iron containing heme groups).

36
Q

Describe the role of cytochrome C:

A

Receives e- from complex III.

37
Q

Describe the role of complex IV (cytochrome oxidase). (4)

A

Receives e- from cytochrome C, transfers e- to O2 to produce H2O, pumps protons from matrix into intermembrane space and also contains cytochromes.

38
Q

What are cytochromes and why are they important for the ETC?

A

They are iron containing heme proteins which are important for the ETC because iron can act as an electron donor or acceptor.

39
Q

What is the chemical formula for reduced and oxidized iron?

A

Fe(2+) is reduced form, Fe(3+) is oxidized form.

40
Q

Where are cytochromes found in the ETC? What about Cytochrome C specifically?

A

They are found in enzyme complexes, although cytochrome C is stand alone.

41
Q

Why doesn’t FADH2 enter the ETC at complex I like NADH?

A

FADH2 has lower free energy than NADH and enters the ETC at a lower energy via complex II.

42
Q

Define chemiosmosis:

A

It is the movement of protons (H+) across a selectively permeable membrane by passive transport (exergonic).

43
Q

Define oxidative phosphorylation.

A

it is when chemiosmosis (exergonic) is coupled to the production of ATP by ATP synthase (endergonic).

44
Q

For oxidative phosphorylation to occur, what must the concentration of protons (H+) in the intermembrane space be in comparison to the concentration of protons in the matrix?

A

[H+] intermembrane space > [H+] matrix.

45
Q

What is ATP synthase? Where is it located? What does it do? How is it powered?

A

It is an enzyme embedded in the inner mitochondrial membrane. It synthesizes ATP from ADP and Pi. It is powered by the proton gradient generated by ETC.

46
Q

In cellular respiration, how much ATP is produced by oxidative phosphorylation (ATP synthase) per glucose molecule?

A

Oxidative phosphorylation produces 28 ATP.

47
Q

How much CO2 and ATP is produced per glucose molecule in cellular respiration?

A

6 CO2 and 32 ATP.

48
Q

Which component(s) of cellular respiration produce CO2? How much?

A

2 CO2 is produced in pyruvate oxidation and 4 CO2 from the citric acid cycle.

49
Q

Which component(s) of cellular respiration produce ATP? How much?

A

2 ATP from glycolysis (substrate-level phosphorylation), 2 ATP from the citric acid cycle (substrate-level phosphorylation) and 28 ATP from the ETC (oxidative phosphorylation).

50
Q

Describe the contribution of NADH and FADH2 to the production of ATP in the electron transport chain.

A

10 NADH allow for the production of 2.5 ATP each, resulting in 25 ATP produced from NADH in the ETC. 2 FADH2 allow for the production of 1.5 ATP each, resulting in 3 ATP produced form FADH2 in the ETC. The total number of ATP produced in the ETC is 28.

51
Q

Where does the 10 NADH used in the ETC come from?

A

2 from glycolysis, 2 from pyruvate oxidation and 6 from the citric acid cycle.

52
Q

Where does the 2 FADH2 used in the ETC come from?

A

Both are produced in the citric acid cycle.

53
Q

What is the maximum amount of ATP that can be produced from a single glucose molecule by cellular respiration?

A

32 ATP.

54
Q

Why does 1 molecule of FADH2 produce less ATP than 1 molecule of NADH?

A

FADH2 bypasses complex I in the ETC (a proton pump), therefore it contributes less to the H+ gradient.

55
Q

What would happen if a proton (H+) channel were inserted into the inner mitochondrial membrane?

A

The result would be a process called uncoupling: less H+ moves through ATP synthase and thus more energy is lost as heat. The (spontaneous) gradient is uncoupled from (non-spontaneous) ATP synthase.

56
Q

Can cellular respiration extract energy from other organic molecules? (other than glucose).

A

Yes, such as proteins and fats.

57
Q

How does cellular respiration extract energy from proteins?

A

Proteins can be broken down into amino acids (this releases ammonia (NH3)) and these amino acids can be broken down into pyruvate, acetyl-CoA and a-ketoglutarate.

58
Q

How does cellular respiration extract energy from fats?

A

Fats can be broken down into glycerol molecules and fatty acids. The glycerol then contribute G3P to cellular respiration and fatty acids can be transformed into acetyl-CoA by B-oxidation.

59
Q

What can cells do to respond to metabolic needs?

A

Cells can regulate reaction rates to respond to metabolic needs.

60
Q

In what way is cellular respiration regulated?

A

ATP, AMP and citrate are allosteric regulators of the enzyme phosphofructokinase (PFK), which catalyzes the 3rd reaction of glycolysis. ATP (final product) and citrate (intermediate product) inhibit PFK, while AMP stimulates it.

61
Q

In what way can some cells make ATP without O2?

A

By fermentation.

62
Q

Define fermentation (most general definition).

A

It is the anaerobic catabolism of organic nutrients.

63
Q

How is ATP produced in fermentation? Why is it anaerobic? How much ATP is produced? Why doesn’t fermentation result in a shortage of electron carriers?

A

ATP is produced by glycolysis only (no ETC so no O2 is needed). 2 ATP is produced per glucose molecule. Fermentation recycles NAD+ from NADH so glycolysis can continue.

64
Q

What are the 2 types of fermentation and where do they occur?

A

Alcohol fermentation (occurs in yeast and many bacteria) and lactic acid fermentation (occurs in human muscles and some bacteria).

65
Q

What is being reduced in alcohol fermentation?

A

Acetaldehyde reduced to ethanol.

66
Q

What is being reduced in lactic acid fermentation?

A

Pyruvate reduced to lactate.

67
Q

What do fermentation and cellular respiration have in common?

A

Both pathways use glycolysis to oxidize glucose to pyruvate.

68
Q

What are the 3 primary differences between fermentation and cellular respiration?

A

The oxidation of NADH to NAD+, the final e- acceptor and the amount of ATP produced.

69
Q

How is NADH oxidized to NAD+ in fermentation vs cellular respiration?

A

When reducing acetaldehyde to ethanol (alcohol fermentation) or reducing pyruvate to lactate (lactic acid fermentation) vs at the ETC in cellular respiration.

70
Q

What is the final e- acceptor in fermentation vs cellular respiration?

A

Acetaldehyde (alcohol fermentation) or pyruvate (lactic acid fermentation) vs O2 in cellular respiration.

71
Q

How much ATP is produced in fermentation vs cellular respiration?

A

2 (fermentation) vs 32 (cellular respiration).

BIO 2 (14 decks)

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