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Biochemistry Exam 2 > Chapter 20: ETC and Chapter 21: Proton-Motive Force > Flashcards

Chapter 20: ETC and Chapter 21: Proton-Motive Force Flashcards

1
Q

Oxidative phosphorylation takes place in _______ and is the major source of _______.

A

Mitochondria

Energy for aerobic organisms

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2
Q

How much ATP is generated from oxidative phosphorylation?

A

26 ATP

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3
Q

Electrons flow from NADH and FADH2 to O2 in the ________.

A

Electron-transport chain or respiratory chain

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4
Q

The electron flow generates a…

A

Proton gradient that powers ATP synthesis

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5
Q

Collectively, the citric acid cycle and oxidative phosphorylation are called…

A

Cellular respiration

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6
Q

Outer mitochondrial membrane is ______ while inner mitochondrial membrane is ______.

A

Outer - permeable

Inner - impermeable

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7
Q

A negative redox potential means that a molecule has…

A

Lower affinity for electrons compared to H2

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8
Q

A positive redox potential means, the molecule has…

A

A higher affinity for electrons

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9
Q

A measure of a molecule’s tendency to donate or accept electrons

A

Redox potential

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10
Q

Only 3 of the 4 protein complexes pump protons. They are…

A
  • NADH-Q oxidoreductase (Complex I)
  • Q-cytochrome c oxidoreductase (Complex III)
  • Cytochrome c oxidase (Complex IV)
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11
Q

The complex that is not a proton pump is called:

A

Succinate Q-reductase (Complex II)

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12
Q

These complexes appear to be associated with one another in what is called the _______.

A

Respirasome

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13
Q

What are the 2 mobile electron carriers?

A
  • Ubiquinone (coenzyme Q or Q)
  • Cytocrome C
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14
Q

How many protons are simultaneously pumped out of the mitochondria by Complex I?

A

Four

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15
Q

Complex III electron transfer is coupled to the pumping of ______.

A

Two protons from the matrix

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16
Q

Cytochrome c oxidase pumps _______ from matrix to cytoplasmic side

A

Four protons

(This reaction requires oxygen)

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17
Q

The cytochrome c oxidase complex catalyzes the reduction of molecular oxygen. During this catalysis small amounts of superoxide anions and hydrogen peroxide are released. These are called…

A
  • Reactive oxygen species or ROS.
  • ROS are harmful for cells.
  • The cells developed mechanisms to deal with ROS .
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18
Q

What % of oxygen molecules consumed by mitochondria are converted into superoxide ions?

A

2-4%

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19
Q

What two enzymes protect against ROS damage?

A

Superoxide dismutase and catalase

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20
Q

_________ converts superoxide radicals to hydrogen peroxide and water.

A

Superoxide dismutase

21
Q

______ converts hydrogen peroxide into water and oxygen

A

Catalase

22
Q

What is the chemiosmotic theory?

A

Electron transport and ATP synthesis are coupled by a proton gradient across the inner mitochondrial membrane

*ATP synthesis is powered by the proton-motive force

23
Q

Proton-motive force consists of what two gradients?

A
  1. Chemical gradient
  2. Charge gradient
24
Q

The chemical gradient of the proton-motive force…

A

is generated by the difference in pH inside and outside the matrix (outside has more protons and is more acidic than matrix)

25
Q

The charge gradient of the proton-motive force

A

is generated by the charge difference inside and outside the matrix (outside has more protons, which is more positive and matrix has less protons and is more negative).

26
Q

The structure of ATP synthase.

A

It consists of 2 units

  1. Fo= proton-conducting unit –contains the proton channel.
  2. F1= ATP-synthesizing unit, contains the catalytic activity (beta-subunit).
27
Q

How many protons must flow into the matrix for each ATP formed and released by the b subunit?

A

Three protons

28
Q

The __________ accounts for the synthesis of ATP by the b subunit in response to proton flow.

A

Binding change mechanism

29
Q

T or F: Cytoplasmic NADH cannot enter the mitochondria.

A

True

30
Q

Electrons from cytoplasmic NADH are carried across the mitochondrial membrane by two major mitochondrial shuttles:

A
  • Glycerol 3-phosphate shuttle (muscle)
  • Malate-aspartate shuttle (heart and liver)
31
Q

In muscle, electrons from cytoplasmic NADH enter the electron-transport chain via the ________.

A

Glycerol 3-phosphate shuttle

Yields 1.5 ATP

32
Q

In heart and liver, electrons from cytoplasmic NADH are used to generate mitochondrial NADH in ________.

A

Malate-aspartate shuttle

Yield 2.5 ATP

*No energy loss

33
Q

The synthesis of 1 ATP requires ______ (____ in ATP synthesis and ____ for ATP transport)

A

**4 H+ **

3 in synthesis

1 in transport

34
Q

____ protons are translocated per NADH and ____ protons per FADH2.

A

10 protons per NADH

6 protons per FADH2

35
Q

P/O for NADH

A

P/O = (10 H+/ 4 H+) = 2.5 ATP/O

36
Q

P/O for FADH2

A

P/O = (6 H+/ 4 H+) = 1.5 ATP/O

(FADH2 does not pass through complex I)

37
Q

The________ is the most important factor in determining the rate of oxidative phosphorylation. This regulation is called __________.

A
  • Levels of ADP
  • Respiratory control or acceptor control
38
Q

_______ carry protons across the inner mitochondrial membrane. The electron-transport chain functions, but ATP synthesis does not because the proton gradient can never form.

A

Uncouplers

39
Q

Rotenone (fish/insect poison) and amytal (barbiturate sedative)…

A

Block the electron transfer in NADH-Q oxidoreductase

40
Q

Antimycin A…

A

Blocks the electron flow in Q-cytochrome c oxidoreductase

41
Q

CN-, N3 and CO…

A

block the electron transfer in cytochrome c oxidase

42
Q

Oligomycin and dicyclohexylcarbodiimide (DCCD, antifungal agent) inhibits the ATP synthase by…

A

Preventing the influx of protons.

43
Q

_________ uncouples electron transport from phosphorylation in mitochondria by carrying the protons across the inner mitochondrial membrane. It stops ATP synthesis without affecting electron transport from NADH to O2

A

2,4-Dinitrophenol (DNP)

44
Q

NADH is a strong ________ agent and has a ________ redox potential (E0).

A

Reducing agent

Negative redox potential

45
Q

In an experiment, oxidative phosphorylation is inhibited by Antimycin A. Which one of the following molecules will be in the reduced state (received electrons)?

A

Ubiquinone Q

46
Q

Cyctochrome c, a small soluble protein, shuttles electrons from Q-cytochrome c oxidoreductase to:

A

Cytochrome C oxidase

47
Q

In oxidative phosphorylation, the transfer of electrons from NADH to O2 leads to pumping of _________ protons (H+) from the mitochondrial matrix to the intermembrane space.

A

10

48
Q

T or F: The electron transport chain generates a proton gradient that is required for NADH production.

A

False

49
Q

The F1 subunit of the ATP synthase is also known as…

A

ATP synthesizing unit

Biochemistry Exam 2 (10 decks)

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