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Biomolecular Mechanisms > Week 14: (A) Oxidative Phosphorylation > Flashcards

Week 14: (A) Oxidative Phosphorylation Flashcards

1
Q

What is oxidative phosphorylation?

A
  • High energy electrons (carried by NADH and FADH2) are used to reduce O2 to H2O
  • phosphorylation of ADP–> ATP
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2
Q

What is the source of high energy electrons?

A

NADH & FADH2

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3
Q

What is O2 reduced to?

A

H2O

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4
Q

What is the high energy electrons from NAD & FADH2 used for?

A

Their energy is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space

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5
Q

How do these H+ flow back into mitochondrial matrix?

A

Protons flow back across the membrane, following their concentration gradient
-As a potential energy is made

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6
Q

What is a positive redox potential?

A

more positive the redox potential, the more readily a molecule is reduced.

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7
Q

What changes in the redox potential when co-factors move down the electron transport chain?

A

Electrons flow down the electron transport chain. NADH & FADH2 will go from negative to more positive redox potential

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8
Q

what do big jumps in redox potential cause?

A

equate to big changes in ΔG, meaningful work for the cell

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9
Q

Where does oxidative phosphorylation occur?

A

inner membrane of the mitochondria

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10
Q

What do the many invaginations in the mitochondrial membrane allow?

A

increase surface area

allow high conc of enzymes that perform in these e- transport reactions to be concentrated in a space

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11
Q

Are proton pumps close to one another?

A

YES dues to structure of the membrane

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12
Q

What is the coupling of respiration to ATP synthesis called?

A

oxidatie phosphorylation

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13
Q

What are the two stages in oxidative phosphorylation?

A

electron transport & ATP synthesis

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14
Q

What are 3 stages in electron transport?

A
  • Electrons flow from NADH and FADH2 to O2
  • Respiratory chain
  • Energy is used to pump H+ out of the mitochondrial matrix
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15
Q

What are the 2 stages in ATP synthesis?

A
  • Electrochemical gradient of H+ across mitochondrial inner membrane (osmotic charge)
  • Energy stored in this gradient can be used to synthesise ATP
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16
Q

Is electron transport and ATP synthesis catalysed by separate proton pumps?

A

YES

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17
Q

Where do the e- from?

A

NADH & FADH2

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18
Q

What pumps, pump e- across the inner mitiochondrial membrane?

A

complex i, iii & iv

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19
Q

What does the increased positive change in the intermediate space cause?

A

positive charge

electrostatic attractions & conc gradient

20
Q

What channel is used for H+ to flow through back into the matrix?

A

ATP synthase

21
Q

What does ubiquinone do?

A

coenzyme Q, rapidly shuttles within membrane

22
Q

How many of the four respiratory complexes pump H+?

A

3

23
Q

How does the chain of pumps create an electron gradient?

A

Transfer of electrons through the respiratory chain

24
Q

What membrane are the pumps located?

A

inner mitochondrial membrane

25
Q

What has the highest H+ concentration?

A

intermediate space

26
Q

What electron field is made?

A

intermembrane space forms an electrical field with the matrix–> matrix side more negative
due to high H+ charge on outer mitochondrial membrane

27
Q

What happens if you stop the electron flow through the respiratory chain?

A

stop the H+ movement thus stop generation of the potential

28
Q

Why is electron transport energetically favourable?

A

e- moving from a high to low conc

29
Q

What is electron transport coupled with?

A

proton pumping against conc gradient

30
Q

what is the unfavourable reaction in electron transport chain?

A

pumping of h+ against conc gradient

31
Q

What two forces are created by H+ moving against conc gradient?

A

generates. ..
- Membrane potential (large force)
- Conc gradient (smaller force)

32
Q

What is osmotic pressure?

A

concentration gradient of H+ across membrane

33
Q

What is ATP synthase also called?

A

mitochondrial ATPase/

F1F0 ATPase

34
Q

What subunit of the ATP synthase protrudes into the mitochondrial matrix?

A

F1 sub

35
Q

What subunit of the ATP synthase protrudes into the inner membrane?

A

F0 sub

hydrophobic

36
Q

What 2 sections does the ATP synthase have?

A

stator (does not rotate)& rotor (rotate)

37
Q

What subunit contains the proton channel?

A

F0

38
Q

What does the flow of protons cause in the rotor unit of ATP synthase?

A

turns the rotor, confo change leads to ATP synthesis

39
Q

How does the ATP synthase form ATP from ADP + Pi?

A

space conformation change when rotor is moving—>rotation forces the ADP + Pi to come together.
When rotation creates enough space again, ATP is released into the matrix

40
Q

How are spaces created in ATP synthase?

A

The motor causes Alpha & beta complexes to move in and out.

in contact and not in contact alternatively

41
Q

What is the P/O ratio?

A

measurement of the coupling between the ATP synthase & electron transport chain.
How many ATP generated from 1 O2
Number of molecules of inorganic phosphate (Pi) incorporate into ATP per atom of oxygen reduced

42
Q

How many electrons need to flow to oxygen to reduce it?

A

2

so… how many ATP do we make per 2 electrons that flow into the process

43
Q

What does P/O ratio depend on?

A

depends on which substrate is oxidised

NADH or FADH2

44
Q

What is the p/o ratio of NADH to NAD+?

A

2.5

45
Q

What is the p/o ratio of FADH2?

A

1.5

eg 2FADH2 generated 3 ATP

46
Q

What are diseases caused by oxidative phosphorylation?

A

degenerative disease
OXPHOS disease
mutations in mitochondrial or nuclear DNA
symptoms usually appear in tissue with highest ATP

47
Q

What tissue has the highest ATP?

A

nervous system, heart, skeletal muscle, kidney

Biomolecular Mechanisms (34 decks)

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