Chapter 19 Oxidative Phosphorylation Posted

8/8/2019 Chapter 19 Oxidative Phosphorylation Posted

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Oxidative Phosphorylation &Photophosphorylation

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Oxidative Phosphorylation

All oxidative steps converge at this finalstage of cellular respiration in which theenergy of respiration drives the_______

Photophosphorylation:

Photosynthetic organism capture energy of______________

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Oxidative phosphorylation:- Occurs in ____________

- Reduction ofO2 to______with

electrons donated by _____ & _____

- Ultimate electron acceptor________?

Photophosphorylation:- Occurs in ____________

- Oxidation ofH2O to____with_____ as

ultimate electron acceptor.

- Absolutely dependent on _______.

Oxidative Phosphorylation


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Mitochondria

Selectively ____________inner membrane- ___________ the intermediates and enzymes of

cytosolic pathway from ones in matrix,

Specific_____________are deployed to exchangesome of the components. e.g.

into matrix:

out of matrix:

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Electron Acceptors

Electrons from catabolic reactions are collected byuniversal electron acceptors:

NAD+,NADP+

FAD,FMN

Respiratory chain consists of series of sequentiallyacting electron carriers.

- mostly integral proteins with prosthetic groups

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Electron carriers

1. A hydrophobic quinone (Ubiquinone)/Q- lipid __________- long isoprenoid side chain

- plastoquinone- menaquinone

Two iron containing proteins:

2. cytochromes:

3. iron sulfur protein:

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Accepts_______to becomesemiquinone radical (QH).

or__e- to form ubiquinol (QH2)

Electron carriers:

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Mitochondria has 3 classes ofcytochromes (a, b, c)distinguished by _______________________

Strong light absorption-due to__________________.

All are integral protein of ___________________

except: cytochrome C which is_____

Electron carriers: Cytochromes

Covalent bondsto protein

cyt b cyt c

Fig 19.3

cyt a

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Iron present____in heme but in association with sulfur atomsof Cys residues/ inorganic Sulfur.

Simple structure:

Complex :

Rieske iron-sulfur proteins (1Fe+2___residues)

Fig 19.5 a-cIron Sulfur Proteins


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Mitochondrial Respiratory Chain

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NADH: ubiquinone oxidoreductase/ or NADH dehydrogenase

Complex I

Catalyzes two reactions:

A. Exergonic transfer ofa hydride ionfrom _____ & a_____from the matrix:

NADH + H+ + Q p NAD+ + QH2

B. Endergonic transfer of- 4 H+ from matrix to the

_____________________(IMS).by proton pump driven by energyof____________transfer.

Results in________charged matrix &_________________charged IMS

NADH + 5H+N + Q p NAD+ + QH2 + 4H

+p

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Ubiquinol (___) ______ in the inner mitochondrial

membrane from complex I to complex ____.

There it is oxidized to Q in a process involving___________movement of H+.

Complex I

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- membrane bound enzyme of TCA cycle

________________________________.

Fig19.8

Complex II

Fig 16.7

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The path of electron transfer from succinate binding siteto_________________, then through the Fe-S center to the______________.

Complex II

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cytochrome bc1 complex

Couples the transfer ofelectrons

from_______________(QH2) to

_____________, with transport of

H+ from matrix to intermembrane

space.

QH2 + 2 cyt c1(oxid) + 2H+Np Q + 2 cyt c1 (redu) + 4 H

+p

Complex III

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____ H+

are translocatedfor each____ of electronpassing thru complex IIIto cytochrome c.

QH2 is oxidized to Q____ molecules ofCyto care reduced.

Complex III

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Cytochrome C

Cytochrome c(____________ protein)

- after accepting electronsfrom complex III, moves

to complex_____todonate the electrons.

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Cytochrome oxidase

- carries electrons from cyt C to_______________, reducing itto________.

- Subunit II has 2 Cu (CuA) ionsin complex with

2 _____________________as in 2Fe-2S center.

Complex IV

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Cytochrome oxidase

-Subunit I has 2 heme groups(a & a3) and another __________(Cu

B)

- e- transfer through complex IVfrom cyt cp CuA p heme a pheme a3-CuB center and finally

to _____.

Complex IV

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Complex IV:

Overall reaction catalyzed by complex IV:

4 cyt c (reduced) + 8 H+N + O2 p4 cyt c (oxidized) + 4 H+P + 2H2O

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Energy of electron transfer isconserved:

Transfer of2 electrons from NADH thru tomolecular O2.

(G = _______kJ/mol (NADH)

From succinate: (G = _________kJ/mol

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- A Proton Gradient is produced whichhas_____________

Protons pumped/electron pair:

__ by complex-I__ by complex-III__ by complex-IV

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1. Proton concentration

2. Separation of charges

Energy has two components:

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ATP synthesis

How is proton flux coupled with phosphorylation?

Synthesis ofATP results into___________flow ofH+ back intomatrix through a proton pore associated with_____________.

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ATP synthase

F0 complex (bottom orange)

F1 complex (ATP Synthase)

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ATP synthase

- 3 subunit differ in their

________________.

- Results in differences in theirATP/ADP binding sites:

- this difference in binding is__________ for themechanism of action.

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Rotational catalysis

-3 active sites of___take turn

in catalyzing ATP synthesis-rotational catalysis.

Any subunit starts in:

- -ADP conformation subunitbinds_____ &____from mediumand changes to:

- -ATP, finally subunit changes to:

- -empty to release ATP due to its

low affinity for _______.

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Proton Gradient Drives Membrane Transporters

Inner membrane is

_________________:

Specific transportersneeded to bring ADP & Piinto matrix and take out

ATP to_______.

1. Adenine nucleotidetranslocase

ATP out (4), ADP in (3)net ____ out (favored)matrix has net __________charge.

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Proton Gradient Drives Membrane Transporters

2. ATP synthaseH+ in net +1 in (favored)

3. Phosphate translocase

-promotes one H2PO4 (Pi)

in (_____),-H+ in (_____)

- No net change

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Regulation ofOxidative Phosphorylation

Most of ATP in aerobic cells.

Glucose: complete oxidation=_____ ATP

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Glucose-glycolysis-anaerobic-___ATP

Palmitate (CoA derivative) oxidation

to CO2 yields_______ATP

Vast majority of ATP are produced incatabolism by electron transfer to _____.

Regulation is important to meet __________________ needs of the cell.

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Availability of______for phosphorylation(acceptor [Pi] control)

- Rate of respiration (____ consumption) is

controlled by ADP availability

- ADP concentration= __________ status

- ATP formed as fast as it is_________.

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Respiration slows downwhen cell has adequetesupply of _______.

Except in____________

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Mammal ________________ have adipose tissue(______________): serves to produce_________:

protons are allowed to pass through __________protein (Thermogenin) in the inner membrane.

Brown color = ____________________________________

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Heat for Pollination

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ATP production:

coordinately regulated

___/___concentrationcontrols:

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Mitochondrial gene mutation:Human disease

Why inherited from mother?

Lebers hereditary optic neuropathy

Myoclonic epilepsy

ragged-red fiber disease.


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Mitochondria: Apoptosis &Oxidative Stress

Mitochondria also participates in processesassociated with____________________.

Apoptosis?

Triggered by__________________.

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Permeability of outermitochondrial membrane ________

Cytochrome c ______________:- where it activates ________.


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Mitochondria: Oxidative Stress

M

itochondria: free radicals.

Possible sites of production:

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NADH is needed in the mitochondrial matrixfor electron transport chain to utilize it for_________ production.

While NADH which is produced by glycolysisin_________________.

How is it transported to matrix of mitochondria?

Transport of NADH

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The most active_____________inmitochondria of heart, liver, kidney is the

_______________________.

Skeletal muscle and brain use a different

shuttle:__________________________

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46Malate-aspartate shuttle


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Glycerol 3-Phosphate Shuttle

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Photophosphorylation


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Photosynthesis: Harvesting light energy

Light driven _______________

Solar energy: driving force for thecontinuous cycling of_____________

Photosynthesis:

H2O donates electrons (H) forreduction of______________________

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Chloroplasts

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h f h


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Chlorophylls a &b (higher plants)

Bacteriochlorophyll (photosynthetic bacteria)

Primary Gathers of Light

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Accessory pigments

- Carotene Lutein

Lutein (xanthophyll)

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Photosystems

Light harvesting

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Photochemical Reaction Center

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Photosynthetic bacteria:

- have one photosystem.- lack ability to use light energy to__________

Cyanobacteria, green algae, higherplants:

- Have _________ photosystems.

- Can generate O2 from____________

Photosystems

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Bacterial Reaction Center

Cytochrome bc1 complex

Fig 19-54.

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Bacterial Reaction Center

1. Cytochrome bc1complex(like type II)

2. Ferredoxin (Fe-S)Cyclic electron

flow

QH2moves

Fig 19-54.

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PS I - like type I

PS II - like type II

Cyclic & noncyclicmakes______

Modern Photosynthates


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Noncyclic Electron Flow: Z scheme

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Cyclic Electron Flow

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L li ti f PSI d PSII


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Localization of PSI and PSII

Stroma

Lumen

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L li ti f PSI d PSII


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Localization of PSI and PSII

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ATP &NADPH produced in the light reactions areused in the_____________________reactions.

Need__________________

Noncyclic reactions produce_______

Cyclic reactions produce______________.

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Proton Movement & Orientation of ATP Synthase


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Proton Movement & Orientation of ATP Synthase

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Hydrogen donors other than H O


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Hydrogen donors other than H2O

Anaerobic (cannot tolerate O2)

Some use:

inorganic compounds

Organic compounds:

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Chapter 19 Oxidative Phosphorylation Posted