Electron Transport And Oxidative Phosphorylation

Front 1

What essential question does electron transport and oxidative phosphorylation answer?

Back 1

-How cells oxidize NADH and FADH2

-Converting their reducing potential into ATP

Front 2

Organization of the electron transport chain

Back 2

•Four protein complexes in theinner mitochondrial membrane

•A lipid soluble coenzyme (UQ,CoQ) and a water soluble protein (cyt c) shuttle between proteincomplexes

•Electrons generally fall inenergy through the chain - from complexes I and II to complex IV

Front 3

in the mitochondrion....

(1) Electron Transport:

(2) Oxidative Phosphorylation:

Back 3

(1) electrons carried by reduced coenzymes generate a proton gradient across the inner mitochondrial membrane

(2) the proton gradient runs 'downhill' to drive the synthesis of ATP

Front 4

Fig. 20.29

Electron Transport and Oxidative Phosphorylation inhibitors:

Back 4

Front 5

What do uncouplers do? (1) of 4

Back 5

1) uncouplers disrupt the tight coupling between electron transport and oxidative phosphorylation by dissipating the proton gradient

Front 6

What do uncouplers do? (2) of 4

Back 6

Chemical uncouplers are hydrophobic molecules with a dissociable proton

Front 7

What do uncouplers do? (3) of 4

Back 7

They shuttle back and forth across the membrane, carrying protons to dissipate the gradient.

Front 8

what do uncouplers do? (4) of 4

Back 8

some naturally occurring proteins are uncouplers:

ex. UCP/ thermogenin help maintain body temperature

Front 9

Uncouplers (chemical or proteinaceous) diagram:

Back 9

Front 10

Structures of common uncouplers:

Back 10

Front 11

What does ATP-ADP Translocase do?

Back 11

Translocase mediates the movement of ATP and ADP across the mitochondrial membrane

Front 12

ATP must be transported out of the mitochondria:

1) What transports ADP in?

2) Why is ATP movement out favored?

3) Is ATP out and ADP in equivalent to a negative charge out?

4) How many H+ does every ATP transported out cost?

5) How many H+ does one ATP synthesis cost?

6) How many H+ does the synthesis and transport of one ATP cost?

Back 12

1) translocase

2) because the cytosol is "+" relative to the "-" matrix

3) yes, it is equivalent to an H+ going in

4) one H+

5) three H+

6) 3 H+ (synthesis) + 1H+ (transport) = 4 H+ (total)

Front 13

Outward transport of ATP is favored by the membrane electrochemical potential (figure)

Back 13

Front 14

How many ATPs are made per electron pair through the chain?

1) Electron pair from NADH to Oxygen:

2) Electron pair from FADH2 to Oxygen:

Back 14

1)

- ETC yields 10 H+ pumped out per electron pair from NADH to Oxygen

- 4 H+ flow back into the matrix per ATP to cytosol

- 10/4 = 2.5 for electrons entering as NADH

2)

- For FADH2 about 6 H+ pumped per electron pair to oxygen

- 6/4 = 1.5 for electrons entering as FADH2

Front 15

How are the electrons from cytosolic NADH fed into Electron transport?

Back 15

-shuttle systems result in electron movement without actually carrying NADH

-Glycerophosphate shuttle: stores electrons in glycerol-3-P, which transfers electrons to FAD

-Malate-Aspartate shuttle: uses malate to carry electrons across the membrane

Front 16

the Glycerophosphate Shuttle:

What does it do? + Figure

Back 16

- couples the cytosolic oxidation of NADH with mitochondrial reduction of [FAD]

Front 17

The malate-aspartate shuttle: (Figure)

Back 17

Front 18

Net yield of ATP from Glucose Oxidation: glycerol-3-P shuttle used

Back 18

30 ATP per glucose

Front 19

Net yield of ATP from Glucose Oxidation:

Malate-Aspertate shuttle used

Back 19

32 ATP per glucose

Front 20

Net yield of ATP from Glucose Oxidation:

Bacteria

Back 20

No mitochondria - no extra H+ used to export ATP to cytosol:

10/3 = approximately 3 ATP / NADH

6/3 = approximately 2 ATP / FADH2

Front 21

Yield of ATP from Glucose Oxidation

Back 21