Lecture 13: Cellular Respiration (Part 1) Flashcards

1
Q

(Review) What are the three modes of production of ATP?

A
  1. oxidative phosphorylation
  2. photophosphorylation
  3. substrate level phosphorylation (fermentation)
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2
Q

What is the formula for ATP synthesis?

A
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3
Q

From what do chemotrophs produce ATP from?

A

from fuels that act as electron donors.

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4
Q

What are the “electron donors” that chemotrophs produce their ATP from?

A

A. Organic compounds
B. Inorganic chemicals

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5
Q

How do you call the chemotrophs that use organic compounds as fuel?

A

chemoorganotrophs

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6
Q

How do you call the chemotrophs that use inorganic chemicals as fuel?

A

chemolithotrophs

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7
Q

From what domains are chemoorganotrophs?

A

species from all domains can be chemoorganotrophs

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8
Q

From what domains are chemolithotrophs?

A

Some species of Bacteria and Archaea

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9
Q

What type of cellular respiration needs O2?

A

Aerobic Cellular respiration

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10
Q

What type of cellular respiration doesn’t need O2?

A

Anaerobic cellular respiration and fermentation

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11
Q

What type of organisms do aerobic cellular respiration?

A

Prokaryotes and Eukaryotes

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12
Q

What type of organisms do anaerobic cellular respiration?

A

prokaryotes

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13
Q

What type of organisms do fermentation??

A

Prokaryotes and Eukaryotes

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14
Q

How much ATP does aerobic cellular respiration make per glucose molecule?

A

30-32 ATP/glucose

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15
Q

How much ATP does anaerobic cellular respiration make per glucose molecule?

A

intermediate 2 ATP/glucose

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16
Q

How much ATP does anaerobic cellular respiration make per glucose molecule?

A

2 ATP/glucose

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17
Q

What happens during glycolysis?

A

glucose is broken down to pyruvate

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18
Q

What is the equation of glycolysis?

A
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19
Q

What are the two phases of glycolysis?

A

A. an energy investment phase
B. an energy payoff phase

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20
Q

What happens during the energy investment phase of glycolysis?

A

2 molecules of ATP are consumed.

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21
Q

What happens during the energy payoff phase of glycolysis?

A

A. 2 molecules of NAD+ are reduced to NADH
B. 4 molecules of ATP are formed by substrate-level phosphorylation

(energy produced)= 4 ATP + 2 NADH

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22
Q

What is the net end result of the two phases in glycolysis? (calculate ATP separately)

A

(summary) = 2 ATP + 2 NADH

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23
Q

Is fermentation a type of aerobic or anaerobic energy metabolism

A

anaerobic energy metabolism

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24
Q

What is the function of facultative anaerobes?

A

they can carry out aerobic cellular respiration when oxygen is present but switch to fermentation in the absence of oxygen

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25
Q

Where does energy yield (“energy income”) comes from in fermentation?

A

glycolysis

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26
Q

When does fermentation pathway keep glycolysis running?

A

as long as there is absence of O2

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27
Q

In how many steps does glycolysis occur?

A

10 steps

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28
Q

What is a faculative anaerobe?

A

an organism that can survive and grow in the presence or absence of oxygen.

These organisms have metabolic pathways that allow them to switch between aerobic (oxygen-requiring) and anaerobic (oxygen-independent) modes of respiration, depending on the availability of oxygen in their environment.

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29
Q

What is the role of pyruvate in a facultative anaerobe?

A

serves as a “fork” in the metabolic road that leads to two alternative catabolic routes.

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30
Q

Glycolysis runs in the absence if what?

A

oxidative phosphorylation

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31
Q

What will eventually run out as glycolysis keeps running?

A

NAD+ (tied up in NADH)

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32
Q

Write a summary reaction of glycolysis.

A
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33
Q

What prevents NAD+ from running out so glycolysis can keep running?

A

Fermentation is a metabolic pathway that regenerates NAD+ from stocks of NADH.

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34
Q

What happens if we change the molecules that act as oxidizing agents in a reaction?

A

different byproducts are formed

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35
Q

What type of fermentation occur in humans? In what types of cells?

A

lactic acid fermentation

muscle cells

36
Q

Is there any intermediate(s) in lactic acid fermentation?

A

no, pyruvate accepts electrons from NADH directly

37
Q

Where do pyruvate get its electrons from in lactic acid fermentation?

A

NADH

38
Q

What is the enzyme used in lactic acid fermentation?

A

lactate dehydrogenase

39
Q

What are the products from lactic fermentation?

A

lactate (2) and NAD+ (2)

40
Q

Where other than animal cells can lactic fermentation occur?

A

in bacterias

41
Q

In what industry is lactic acid fermentation and alcohol fermentation employed?

A

in the food and beverage industry

42
Q

Where does alcohol fermentation occur?

A

in yeast

43
Q

Is there any intermediate in alcohol fermentation?

A

Yes, acetaldehyde

44
Q

What is the enzyme that break down pyruvate into acetaldehyde and carbon during alcohol fermentation?

A

pyruvate decarboxylase

45
Q

What is the enzyme that breaks down acetaldehyde in alcohol fermentation?

A

alcohol dehydrogenase

46
Q

What is the role of the intermediate in alcohol fermentation?

A

to accept the electrons from NADH to produce NAD+ and the product

in the case of alcohol fermentation, the intermediate is acetaldehyde and the product is ethanol

47
Q

What is the equation for aerobic cellular respiration? give a general equation and the balanced equation

A
48
Q

4 steps of aerobic cellular respiration?

A

A. Glycolysis
B. Pyruvate Processing
C. Citric Acid Cycle
D. Oxidative Phosphorylation (Electron transport and chemiosmosis)

49
Q

Where does glycolysis happen?

A

cytosol

50
Q

Where does the three last step of aerobic cellular respiration happen?

A

in the mitochondria

51
Q

What are the parts of a mitochondrion?

A
52
Q

What parts of the mitochondrion contains protein machinery for cellular respiration?

A

the inner membrane and the matrix

53
Q

How does the structure of the inner membrane correlate with its function?

A

maintains the proton gradient that drives oxidative phosphorylation

54
Q

What happens during pyruvate processing?

A

pyruvate is oxidized to form acetyl CoA

55
Q

What other than pyruvate is produced during glycolysis?

A

NADH (electron carrier) and ATP

CO2 not produced yet

56
Q

What is produced during pyruvate processing?

What is the function of this step?

A

NADH produced CO2 generated

no ATP produced

Links glycolysis to the citric acid cycle

57
Q

What is produced during the citric acid cycle?

A

ATP produced
NADH and FADH2 produced
CO2 generated

58
Q

What happens during the citric acid cycle?

A

acetyl CoA is oxidized to CO2

59
Q

What happens during oxidative phosphorylation?

A

electron carriers that were reduced in steps A– C are oxidized in reactions leading to ATP production.

60
Q

What is produced during oxidative phosphorylation?

A

ATP produced by cashing in electron carriers

61
Q

What is the balanced equation of pyruvate processing?

A
62
Q

How do you call the whole of enzymes that can carry out many reactions in a process?

A

a multienzyme complex

63
Q

What is the multienzyme complex that catalyzes pyruvate processing?

A

Pyruvate Dehydrogenase Complex (PDHc).

64
Q

What goes in pyruvate processing?

A

Coenzyme A

65
Q

What type of cell transport is used for pyruvate to pass from the cytosol to the mitochondrial matrix?

A

secondary active transport

66
Q

What is the overall equation of the citric acid cycle?

A
67
Q

How many reactions happens in the citric acid cycle?

A

Series of 8 reactions carried out in a cyclic pathway.

68
Q

How many reactions happens in pyruvate processing?

A

3 reactions

69
Q

What goes in the citric acid cycle?

A

2 acetyl CoA

70
Q

Where does the citric acid cycle takes place?

A

in the mitochondrial matrix

71
Q

What comes out of the citric acid cycle?

A

carbon skeleton completely decomposed into:

72
Q

What is the first step of eight in the citric acid cycle?

A

Acetyl CoA enters the cycle by combining with oxaloacetate to form citrate.

73
Q

What happens in the remaining seven steps of the citric acid cycle?

A

A series of organic acids are oxidized and recycled

energy carriers are produced

end result: citrate is oxidized back to oxaloacetate

74
Q

Is free energy levels constant during pyruvate processing and the citric acid cycle?

A

no, it changes as glucose is oxidized

75
Q

What does each drop in energy represent in pyruvate processing and the citric acid cycle?

A
76
Q
A
77
Q

Why is regulation of glucose oxidation important?

A

The three specific steps of glucose oxidation regulation determines the energy produced in the body to power activities.

78
Q

What are four ways that enzyme activities can be regulated?

A

A. Substrate Availability
B. Allosteric Regulation
C. Competitive Inhibition
D. Regulatory modifications (e.g., phosphorylation)

79
Q

What are two chemical ratios that can be used to gauge(measure) the energy content of a cell and regulate glucose oxidation?

A
  1. ATP / ADP (or AMP)
  2. NADH / NAD+
80
Q

What type of regulators do ATP/ADP and NADH/NAD+ molecules acts as?

A

allosteric regulators

81
Q

What do cells do when there is abundant amount of ATP production? Why?

A

Cells stop glycolytic reactions

to conserve their stores of glucose for times when ATP is scarce (limited)

82
Q

Describe the inhibition that happens in glycolysis when there is abundant amount of ATP.

A

During glycolysis, high levels of ATP inhibit the enzyme phosphofructokinase, which
catalyzes one of the early reactions of glycolysis.

83
Q

Is the inhibition of phosphofructokinase reversible?

A

no since its inhibition is too exergonic to be reversible. (delta G= -3.4 kcal/mol)

84
Q

Why is PFK a good target for allosteric inhibition by ATP?

A

because it is an enzyme that targets one of the early steps of glycolysis and therefore, no energy is wasted on the reactions before the activity is stopped.

85
Q

How many binding sites does PFK (phosphofructokinase) have for ATP?

A

Two:
1. Active site
2. Regulatory site

86
Q

How does the regulatory site play a role in the activity of PFK?

A

When ATP levels are high, ATP will bing to the regulatory site,, which changes PFK’s shape and reduces its activity at the active site

reduced activity at the active site will decrease the reaction rate