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EOM Test 4 > Oxidative Phosphorylation > Flashcards

Oxidative Phosphorylation Flashcards

1
Q

What are cytochromes?

A

Iron coordinating porphyrin ring derivatives

One electron carriers

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2
Q

What are Iron sulfer clusters?

A

Iron and sulfer atoms coordinated by cysteine residues

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3
Q

What is Ubiquinone?

A

Small, mobile carrier that transfers electrons between the primary dehydrogenases and cytochrome b

Reduced form donates its electrons to Complex III

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4
Q

What is Rieske irone sulfur protein?

A

Non-heme-iron protein component of complex III

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5
Q

How are electrons transferred through complex I?

A

NADH transfers two electrons to ubiquinone

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6
Q

How many protons are transported through complex I?

A

4

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7
Q

What is complex II and how are electrons transported through it?

A

Succinate dehydrogenase

FAD accepts two electrons from succinate, which are eventually transferred to ubiquinone via iron-sulfur centers

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8
Q

What is complex III and how are electrons transferred through it?

A

Ubiquinone: Cytochrome c oxidoreductase

Uses two electrons from QH2 to reduce two molecules of cytochrome c

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9
Q

What is Cytochrome c?

A

Mobile electron carrier that moves through the intermembrane space

Carries electron from the cytochrome bc1 complex to cytochrome oxidase

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10
Q

What is the Q cycle?

A

The process by which electrons a recycled in complex III via a semiquinone radical

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11
Q

How does the Q cycle contribute to the proton gradient?

A

When semiquinone accepts its second electron, it extracts two more protons from the matrix in addition to the four that have been pumped out via the two electrons that were transferred to cytochrome c

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12
Q

What is complex IV and how are electrons transferred through it?

A

Cytochrome c donates its electrons to CuA–>CuB

CuB transfers FOUR electrons to ONE oxygen molecule

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13
Q

How many protons are transferred through complex IV per oxygen?

A

4

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14
Q

What is the function of the Malate-Aspartate shuttle and where does it take place?

A

Moves NADH from the cytosol to the the matrix

Liver, kindey and heart

Generates more ATP than glycerol-3-phosphate shuttle

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15
Q

What is the role of the glycerol-3-phosphate shuttle and where does it take place?

A

Moves NADH from cytosol to inner mitochondrial space

Skeletal muscle and brain

Donates electrons to FADH2, skipping complex I, and therefore generating less of a proton gradient

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16
Q

Why is the proton-motive force an electrochemical gradient?

A

Chemical difference - pH gradient generated by H+

Electrical difference - Charge difference generated from H+

17
Q

What is the function of amytal and rotenone?

A

Complex I inhibitor

18
Q

What is the role of antimycin A?

A

Complex III inhibitor

19
Q

What is the function of cyanide, CO, hydrogen sulfide, and sodium azide?

A

Complex IV inhibitor

20
Q

What is the function of oligomycin?

A

Complex V or ATP synthase inhibitor

21
Q

What are the two functional units of ATP synthase?

A

F1 - soluble part of the complex exposed to matrix, catalyzes formation of ATP

Fo - integral part, transports protons to matrix

22
Q

How is ADP and phosphate stabilized in ATP synthase?

A

Positively charged amino acids

23
Q

Describe the binding-change model for ATP synthase?

A

Proton translocation causes rotation and conformational change within all three aB pairs in Fi

Conformational changes between open, loose, and tight causes the formation of ATP

24
Q

What is the function of IF1?

A

Inhibits ATPase activity by binding to two ATP synthase molecules

Only active at low oxygen and low pH

25
Q

What is the function of adenine nucleotide translocase?

A

Antiporter that exchanges ADP for ATP across the inner membrane

Uses up membrane potential - one charge per ATP

26
Q

What is the function of Phosphate translocase?

A

Symporter that moves Phosphate and H+ into the matrix

Uses up pH gradient - one mol H+ per mol ATP

27
Q

How many H+ are needed per ATP molecule generated and why?

A

3 H to synthesize one ATP through ATP synthase

1 H to transport P- into the matrix

28
Q

How many ATP are generated per NADH?

A

2.5

29
Q

How many ATP are generated per FADH2?

A

1.5

EOM Test 4 (19 decks)

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