oxidative phosphorylation Flashcards

1
Q

oxidative phosphorylation

A

-harvest ATP from the oxidation of NADH and FADH2 using O2
-occuris in the mitochondrial inner membranes
-electrons from NADH and FADH2 are transferred to O2 (oxidation)
-the electron transfer is couple with transfer of proton across membrane, generating PMF

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2
Q

complex 1

A

-NADH ubiquinone oxidoreductase
-electron transder from NADH to ubiquinone
-major source of ROS that damages mitochondrial DNA and causes aging
-inhibited by rotenone

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3
Q

complex 2

A

-succinate dehydrogenase
-electron transfer from succinate to ubiquinone
-part of TCA cycle
-no proton transfer
-some other enzymes also pass electrons to ubiquinone via FADH2

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4
Q

complex 3

A

-cytochrome bc1 complex (membrane bound protein complex of 500 kDa)
-electron transfer from ubiquinone to cytochrome c

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5
Q

cytochromes

A

-proteins that contain heme groups
-iron in heme is alternately oxidized or reduces
-mammalian mitochondria have 3 types of cytochromes

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6
Q

complex 4

A

-cytochrome c oxidase
-cytochrome c is mobile electron carrier
electron transfer from cytochrome c to O2
-inhibited by cyanide (CN-), azide (N3-), and carbon monoxide (CO) (bind to iron in heme of cytochrome c oxidase)

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7
Q

F1F0-ATP synthase

A

-located in the inner mitochondrial membrane
-synthesizes ATP using the proton gradient
- the active site is in the B-subunit; the three B subunits have different conformations, which are necessary for ATP synthesis

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8
Q

_______ through the F0 subunit causes rotation of F1, which results in conformational chances in the B subuntis

A

movement of protons

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9
Q

conformational changes in the B subunits cause the synthesis and release of

A

ATP

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10
Q

uncouplers

A

-uncouple oxidation and ATP synthesis
-dissipate the protein gradients by shuttling protons across the inner mitochondrial membrane
-oxygen is consumed without ATP synthesis
-energy is lost as heat

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11
Q

UCP-1

A

-uncoupling protein
-expressed in brown adipose tissues, which play a major role in nonshivering thermogenesis, especially in newborns
-located in the inner mitochodrial membrane
-dissipates the proton gradient

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12
Q

reactive oxygen species

A

-cytochrome c oxidase catalyzes the reduction of O2 to water by passing one electron at a time without releasing the intermediates
-intermediates are highly reactive and can cause cellular damages
-small number of reactive oxygen species are formed from the leakage i the electron transport chain
-immune cells produce reactive oxygen species using NADPH oxidase to kill bacteria

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13
Q

cellular defenses against reactive oxygen species

A

-superoxide dismutase and catalase
-glutathione peroxidase
-antioxidants

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14
Q

superoxide dismutase and catalase

A

-primary defense mechanism

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14
Q

glutathione peroxidase

A

-uses glutathione as a reductant
-oxidized glutathione is reduced by glutathione reductase using NADPH

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15
Q

antioxidants

A

-vitamin: vitamin C and E
-food: green tea, red wine, blueberry

16
Q

reactive oxygen species and diabetes

A

-too much intracellular glucose leads to overproduction of the superoxide by mitochondria
-cells cannot restrict the uptake of glucose are especially vulnerable
-retina -diabetic retinopathy
-kidney- diabetic nephropathy
-peripheral nerves- diaberic neuropathy

17
Q

in oxidative phosphorylation, the final acceptor of the electrons of NADH and FADH2 is

A

O2