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Biochem Exam 3 > 25 - Oxidative Phosphorylation > Flashcards

25 - Oxidative Phosphorylation Flashcards

1
Q

Mitochondria are a two-membrane system. The (INNER/OUTER) membrane is permeable due to the presence of porin aka VDAC (voltage-dependent anion channels).

A

Outer

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2
Q

Mitochondria are a two-membrane system. The (INNER/OUTER) membrane is impermeable, has metabolite transporters, and is folded into series of cristae.

A

Inner

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3
Q

Mitochondria have two compartments, which are…

A

Intermembrane space

Matrix

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4
Q

This is the site of the TCA cycle and fatty acid oxidation.

A

Matrix of mitochondria

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5
Q

This occurs in the inner membrane (along membrane) of the mitochondria.

A

Oxidative phosphorylation

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6
Q

Mitochondria share an __________ relationship with host cell. They have their own DNA, make proteins and RNAs.

A

Endosymbiotic

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7
Q

Human mitochondrial DNA is (MATERNALLY/PATERNALLY) inherited.

A

Maternally

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8
Q

The TCA cycle generates ______ and ______. In OxPhos these high energy electrons flow through 4 protein complexes called the electron transfer chain (ETC).

A

NADH

FADH2

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9
Q

Electrons reduce molecule O2 to _______.

A

Water

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10
Q

In OxPhos, three of the complexes pump _______ from the matrix to intermembrane space.

A

Protons

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11
Q

Protons return to the matrix by flowing through another complex called…

A

ATP synthase

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12
Q

What is the primary function of OxPhos?

A

ATP synthesis

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13
Q

Which complex in OxPhos does NOT pump protons?

A

Complex II

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14
Q

A successful OxPhos must accomplish the following key goals:

1) To transfer electrons from _______ and _______ to O2.
2) To establish a _______ gradient across the inner mitochondrial membrane.
3) To synthesize _______.

A

NADH
FADH2
Proton
ATP

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15
Q

Electrons transferred from NADH to O2 via three large protein complexes, which are…

A

NADH Q oxidoreductase (Complex I)
Q cytochrome c oxidoreductase (Complex III)
Cytochrome c oxidase (Complex IV)

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16
Q

Electron flow is (EXERGONIC/ENDERGONIC) and powers the flow of protons across the inner membrane.

A

Exergonic

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17
Q

What is the other complex of the ETC that does not pump protons?

A

Succinate Q reductase (Complex II)

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18
Q

Succinate Q reductase (Complex II) has ________ ________ which generates FADH2 in the TCA cycle.

A

Succinate dehydrogenase

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19
Q

Electrons from FADH2 enter through which complex?

A

Q cytochrome c oxidoreductase (Complex III)

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20
Q

Complex I, III, and IV are called…

A

Respirasome

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21
Q

This is what transfers electrons from NADH Q oxidoreductase (Complex I) and succinate Q reductase (Complex II) to Q cytochrome c oxidoreductase (Complex III).

A

Coenzyme Q (Ubiquinone or Q pool)

22
Q

Coenzyme Q has a long tail made of 5 - C ________ units which makes it hydrophobic.

A

Isoprene

23
Q

What is the most common coenzyme Q?

A

CoQ 10

24
Q

This is what shuttles electrons from Q cytochrome c oxidoreductase (Complex III) to cytochrome c oxidase (Complex IV). It is the final component of the ETC and catalyzes the reduction of O2 (to water).

A

Cytochrome c

25
Q

Complex I, aka NADH Q oxidoreductase (NADH dehydrogenase), is a large protein (>900 kDa, with 46 polypeptide chains) and is encoded by both ________ and _______ genes.

A

Nuclear

Mitochondrial

26
Q

This is the first point of entry of electrons from NADH.

A

NADH Q oxidoreductase (Complex I)

27
Q

What is the reaction catalyzed by Complex I?

A

NADH + Q + 5H+ (matrix) —– NAD+ + QH2 + 4H+ (cytoplasm)

28
Q

These are present in non-heme iron proteins and play a role in reduction reactions. They exist in various configurations.

A

Iron Sulfur clusters

29
Q

Iron sulfur clusters undergo oxidation-reduction reactions but the ________ never leave the protein.

A

Protons

30
Q

For example, NADH Q oxidoreductase contains _______ and ______ iron sulfur clusters.

A

2Fe-2S

4Fe-4S

31
Q

FADH2 enters the ETC through this complex, and it is what connects TCA to OxPhos (succinate dehydrogenase).

A

Succinate Q reductase (Complex II)

32
Q

T/F. FADH2 does not leave the complex.

A

True

33
Q

FADH2 does not leave the complex. Its electrons are transferred to FeS and then to Q to form QH2. It does not pump protons. Consequently less _______ is synthesized from the oxidation of FADH2.

A

ATP

34
Q

Electrons from QH2 are passed on to cytochrome c by what?

A

Cytochrome c oxidoreductase (Complex III)

35
Q

The flow of electrons from QH2 to complex III then cytochrome c leads to the transport of _____ protons to the cytoplasmic side.

A

2

36
Q

What is the total reaction in complex III?

A

QH2 + 2 Cyt c(ox) + 2H+(matrix) – Q + 2 Cyt c(red) + 4H+ (cytoplasm)

37
Q

Cytochrome c oxidase (Complex IV) catalyzes the transfer of electrons from reduced Cyt c to molecular ________, the final acceptor. This is what makes these reactions aerobic and makes humans “breathe”.

A

Oxygen

38
Q

_______ electrons are funneled to oxygen to reduce it to water. At the same time, protons are being pumped from matrix to cytoplasmic side of inner membrane.

A

Four

39
Q

What is the total reaction of complex IV?

A

4 Cyt c(red) + 8H+ (matrix) + O2 — 4 Cyt c(ox) + 2 H2O + 4H+ (cytoplasm)

40
Q

Why does cytochrome c oxidase (Complex IV) have 2 heme and 3 Cu groups?

A

Because these groups are electron acceptors and donors

41
Q

The partial reduction of O2 generates highly reactive oxygen derivatives, called…

A

Reactive oxygen species (ROS)

42
Q

ROS (reactive oxygen species) are implicated in many pathological conditions. ROS include what?

A 
Superoxide ion (O2-)
Peroxide ion (O2(2-))
Hydroxyl radical
43
Q

T/F. Free radicals are harmful even at low levels.

A

False. They are not harmful at low levels.

44
Q

This antioxidant is responsible for reducing superoxide ions into molecular oxygen and oxidizing superoxide ions into hydrogen peroxide.

A

Superoxide dismutase (SOD)

45
Q

Hydrogen peroxide is not harmful itself, but it causes problems in DNA by producing what?

A

Hydroxyl radical

46
Q

This antioxidant can break down the hydrogen peroxide into molecular oxygen and water.

A

Catalase

47
Q

This antioxidant is already present in the body and can also break down hydrogen peroxide.

A

Glutathione peroxidase

48
Q

What are 2 other essential antioxidants that people have to consume on their own?

A

Vitamin E

Vitamin C

49
Q

Name two types of superoxide dismutase (SOD).

A

1) Cu/Zn SOD (SOD1) cytosolic

2) Mn/Zn SOD (SOD2) mitochondrial

50
Q

How do antioxidants work?

A

They donate an electron to a free radical, keeping the free radical from stealing one from another molecule creating a free radical cascade. Antioxidants stay stable when they donate electrons, preventing them from becoming free radicals.

Biochem Exam 3 (10 decks)

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