Electron Transport Chain

(Respiratory Chain)

Vladimíra Kvasnicová

Respiratory chain (RCH)

a) is found in all cells

b) is located in a mitochondrion

c) includes enzymes integrated in the inner mitochondrial membrane

d) produces reducing equivalents (NADH+H+, FADH2)

The figure is found at http://plaza.ufl.edu/tmullins/BCH3023/cell%20respiration.html (December 2006)

Respiratory chain (RCH)

a) belongs among oxidative pathways

b) can proceed under both aerobic and anaerobic conditions

c) is a reversible pathway

d) needs oxygen (O2) for its function

The figure is found at

http://www.grossmont.net/cmilgrim/Bio220/Outline/ECB2Figures&Tables_Ed2-Ed1/Chapter14_13/REDOX_POTENTIALS_ElectronTransportChain_Fig14-21.htm

(December 2006)

Gibbs energy

„G“

Redox potential

„E“

reducing properties

oxidizing properties

The figure is found at http://academic.brooklyn.cuny.edu/biology/bio4fv/page/mito_ox.htm (December 2006)

Enzymes of the RCH

a) belong among oxidoreductases

b) can transfer either H or electrons

c) are called Complex I, II, III and IV

d) transfer protons and electrons in the same direction

The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2

proton= H+

electron

= e-

Cytochrome c is drawn wrongly!

It is found in

the intermembra

ne space, bound to the

inner mitochondrial membrane

The function of the RCH

a) is to regenerate NAD+ from NADH

b) is to regenerate NADP+ from NADPH

c) is to regenerate FAD from FADH2

d) is to finish oxidation of energy substrates and conserve their energy in a form of ATP

In reactions of the RCH

a) oxygen is reduced to H2O

b) protons (H+) are transfered into an intermembrane space

c) ATP is produced by the Complex I

d) all reduced coenzymes (NADH+H+ and FADH2) are reoxidized by the same mechanism

The figure is found at http://www.cellml.org/examples/images/metabolic_models/the_electron_transport_chain.gif (December 2006)

Choose correct statement

a) Complex I transfers H+ into an intermembrane space

b) Complex II transfers H+ into an intermembrane space

c) Coenzyme Q accepts e- from both Complex I and Complex II

d) Complex IV transfers electrons to oxygen

The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2

proton= H+

electron

= e-

Cytochrome c is drawn wrongly!

It is found in

the intermembra

ne space, bound to the

inner mitochondrial membrane

Citrate cycle (CC) and the RCH are interconnected

a) by CO2 (produced by CC, used by RCH)

b) by NADH (produced by CC, used by RCH)

c) an enzyme succinate dehydrogenase

d) ATP (produced by RCH, used by CC)

The figure is found at http://www.cellml.org/examples/images/metabolic_models/the_electron_transport_chain.gif (December 2006)

Citrate cycle

succinate DH

Adenosine triphosphate (ATP)

a) can be produced only in a cooperation with RCH

b) can be synthesized only under aerobic conditions

c) is formed from ADP by addition of one phosphate

d) is transported from a mitochondrion into a cytoplasm by exchange with ADP

ATP-ADP translocase

The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2

When the term is used it always means „ATP synthesis“

a) phosphorylation

b) oxidative phosphorylation

c) aerobic phosphorylation

d) substrate level phosphorylation

Oxidative phosphorylation

a) needs proton gradient on the inner mitochondrial membrane

b) is catalyzed by ATP synthase

c) can be interrupted by uncoupling proteins (UCP)

d) means ATP synthesis in any oxidative metabolic pathway

The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2

The figure is found at http://plaza.ufl.edu/tmullins/BCH3023/cell%20respiration.html (December 2006)

ATP synthase

inner mitochondrial membrane

The figure is found at http://departments.oxy.edu/biology/Franck/Bio222/Lectures/March23_lecture_shuttles.htm (December 2006)

Uncoupling proteins

(UCP)

= separate RCH from

ATP synthesis

(the synthesis is interrupted)

energy from H+ gradient is

released as a heat

ATP (or GTP)can be formed by the reactions

a) glucose-6-P + ADP → glucose + ATP

b) succinyl~CoA + GDP → succinate + GTP

c) GTP + ADP → GDP + ATP

d) ADP + ADP → ATP + AMP

Oxidation of NADH+H+ in the RCH produces more ATP than oxidation

of FADH2 because

a) higher proton gradien is made by oxidation of NADH+H+

b) NADH+H+ transfers H to different Complex of the RCH than FADH2

c) more protons are transported to the intermembrane space if NADH+H+ is oxidized

d) more e- are transfered from NADH+H+ to O2

The figure is found at http://web.indstate.edu/thcme/mwking/oxidative-phosphorylation.html (December 2006)

FADH2

Choose correct statement(s) about regulation of RCH and ATP

synthesis

a) O2 decreases the pathways

b) uncoupling proteins increase ATP synthesis

c) ADP increses ATP synthesis

d) NADH+H+/NAD+ increases the pathways