Chapter 15 Cellular Respiration 4

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15.1: Types of respiration: aerobic and

anaerobic

15.2 : Aerobic respiration

15.3 : Anaerobic respiration :

fermentation and application

Describe electron transport chain:

The pathway of electron transport is NADH

dehydrogenase, ubiquinone/CoQ, cyt c

reductase, cyt c, cyt c oxidase.

At the end of this subtopic, students should able to :

Electrons

carried

via NADH

Glycolysis

Glucose Pyruvate

CYTOSOL MITOCHONDRION

ATP

Substrate-level

phosphorylation

Electrons

carried

via NADH

Electrons carried

via NADH and

FADH2

Citric

acid

cycle

Pyruvate

oxidation

Acetyl CoA

Glycolysis

Glucose Pyruvate


ATP ATP

Substrate-level

phosphorylation

Substrate-level

phosphorylation
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Electrons

carried

via NADH

Electrons carried

via NADH and

FADH2

Citricacid

cycle

Pyruvate

oxidation

Acetyl CoA

Glycolysis

Glucose Pyruvate

Oxidative

phosphorylation:electron transport

and

chemiosmosis


ATP ATP ATP

Substrate-level

phosphorylation

Substrate-level

phosphorylation

Oxidative

phosphorylation

A sequence ofelectron

carrier molecules

(membrane proteins)

that shuttle electrons

down a series of redox

reactions that release

energy used to make

ATP

(Campbell,9th edition)

Following glycolysis and the citric acid cycle, NADH

and FADH2 account for most of the energy extracted

from food.

Hydrogen atoms carried by reduced NAD and

FAD are the source of electrons.

These two electron carriers donate electrons to the

electron transport chain.

Which powers ATP synthesis via oxidativephosphorylation.

Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The electron transport chain is in the cristae of the

mitochondrion.

The chains components are proteins, which exist in

multiprotein complexes.

Used to transport a pair of

electronsfrom NADH andFADH2.

The carriers alternate

reduced and oxidizedstates as they accept and

donate electrons.

Electrons drop in freeenergy as they go down the

chain and are finally passed

to O2, forming H2O.

NADH dehydrogenase complex

(Complex I)Flavoprotein

(Prosthetic group-Flavin

mononucleotide)

Transfer electron from NADH to

Coenzyme Q.


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Succinate dehydrogenase complex

(Complex II)

(Prosthetic group-FAD)Transfer electron from Succinate

(Krebs cycle) to Coenzyme Q.

14

Coenzyme Q/CoQ (ubiquinone)

Mobile carriers

Transfer electrons to Cytochromebc1.

Cytochrome bc1 complex (Complex

III)

Cytochrome reductase

Prosthetic group -heme/Fe

Transfer electrons to Cytochrome c.

15

Cytochrome c

Mobile carriers

Transfer electrons to Cytochrome

oxidase.

Cytochrome Oxidase

Prosthetic group -Cu

Cytochrome a and a3

(carrying electrons from food)

INTERMEMBRANE

SPACE

MITOCHONDRIAL MATRIX

H

H H

2 H + 1/2 O2 H2O

NAD

FADH2 FAD

Q

NADH

I

II

III

IV

Cyt c

NADHdehydrogenase

Ubiquinone(Coenzyme

Q)

Cytochrome bc1(reductase)

Cytochrome C

Cytochrome coxidase

Succinatedehydrogenase

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Utilization of NADH &

FADH2

Most energy harvested from Krebs Cycle isconserved in NADH.

Krebs Cycle: 6 NADH

2 FADH2

Link Reaction : 2 NADH

Glycolysis : 2 NADH

1 NADHtransfer a pair of hydrogen atom generates

3 ATP.

1 FADH2, transfer a pair of hydrogen atomgenerates2 ATP.

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How the energyfrom electron transfer

is utilized to form ATP?

NADHdehydrogenase

NADH + H+ passes or lose of hydrogen and its electronto NADH dehydrogenase. NADH+H is oxidized to NAD+.

At one point, hydrogen atoms split to form proton

and electrons.

Ubiquinone (CoQ) then passes the electrons tocytochrome bc1 complex (reductase).

Ubiquinone(coenzyme Q)

Cytochromebc1 complex

The electron is then carried by cytochrome c , to the

cytochrome oxidasecomplex.

Cytochrome oxidase passed electron to Oxygen.

Cytochromeoxidase

Cytochrome C

FADH2 is formed in the Krebs Cycle in the oxidation of

succinatetofumarate.

Transfer the electrons to CoQ, Cyt bc1, Cyt c &

Cyt oxidase.

FADH2FAD


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Electrons drop in free

energy as they go down

the chain.Energy release used by

complex to pumped

protons across the inner

mitochondrial.

Complex :

NADH dehydrogenase

Cytochrome bc1

Cytochrome oxidase

Cytochrome

oxidase

Cytochrome

bc1 complex

NADH

dehydrogenase

Each complex in the chain operates as a proton pump,driving a proton out across the membrane into the

intermembrane space.

The protons diffuse back into the mitochondrial matrixthrough a ATP synthase, which couples this diffusion to

the synthesis of ATP.

Oxygen as a final electron acceptor.

Cytochrome oxidase passes electron to oxygen.

Each oxygen then combines with two protons to form

water O2 + 2 e- + 2 H+ H2O
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Chapter 15 Cellular Respiration 4