electron transport chain by sunil shah (bond king) and groups..

1. Group – 3
Shah Sunil and Groups

2. Respiration
 Respiration Involves :
 Glycolysis,
 Krebs cycle,
 Electron transport and Oxidative
Phosphorylation

3. INTRODUCTION
 Glycolysis :
 Occurs in the cytoplasm.
 Breaks glucose into two molecules of pyruvate.
 Krebs cycle :
 occurs in the mitochondrial matrix.
 degrades pyruvate to carbon dioxide.
 Several steps in glycolysis and the Krebs cycle
transfer electrons from substrates to NAD+, forming
NADH.
 NADH passes these electrons to the electron
transport chain.

4. Mitochondria
 stage 3rd of
respiration
 Occurs in
mitochondria.

5. Mitochondria
 Outer membrane- permeable to
 small molecules
 Inner membrane-
 electron transport
 ATP synthase
 Cristae increase area
 Integrity required for
coupling ETS to ATP
synthesis

6. Mitochondria
 outer membrane relatively permeable
 inner membrane permeable only to those
things with specific transporters
◦ Impermeable to NADH and FADH2
◦ Permeable to pyruvate
 Compartmentalization
◦ Kreb's and β-oxidation in matrix
◦ Glycolysis in cytosol

7. Electron Transport System
 Electron Transport Chain – is a collection
of molecules embedded in the inner
membrane of the mitochondria
◦ Most components are proteins

8. Electron Transport System
 Mechanism the cell that converts the energy in
NADH and FADH2 into ATP.
 Electrons flow along an energy gradient via carriers
in one direction from a higher reducing potential to a
lower reducing potential
 The ultimate acceptor is molecular oxygen.
 At the end of the chain electrons are passed to
oxygen forming water.

9. Electron Transport System
 An NADH molecule begins the
process by “dropping off” its
electron at the first electron
carrier molecule

10. ETS
 Remember: each
component will be 50
NADH
reduced when it accepts 40 I
FADH2
FAD
Multiprotein
FMN complexes
Free energy (G) relative to O2 (kcl/mol)
the electron and oxidized Fe•S
O
Fe•S
Cyt b
II
III
when it passes the 30 Fe•S
Cyt c1
Cyt c IV
electron down to the more 20
Cyt a
Cyt a3
electronegative carrier
molecule in the chain
10
0 2 H ++ 12 O2
H2 O

11. Finally the electron is passed to
oxygen, which is very electronegative. NADH
50
FADH2
I Multiprotein
40 FAD
Free energy (G) relative to O2 (kcl/mol)
FMN complexes
Fe•S II
 The oxygen also picks Fe•S
O
Cyt b
III
Fe•S
up 2 H+ ions from the
30
Cyt c1
Cyt c IV
Cyt a
aqueous solution and 20
Cyt a3
forms water 10
0 2 H ++ 12 O2
H2 O

12. ETS
 FADH goes through 50
NADH
mostly the same FADH2
Multiprotein
Free energy (G) relative to O2 (kcl/mol)
40 I FAD
processes, except it
FMN complexes
Fe•S Fe•S II
O
III
Cyt b
drops off its electron 30 Fe•S
Cyt c1
Cyt c IV
at a lower point on
Cyt a
Cyt a3
20
the ETC 10
0 2 H ++ 12 O2
H2O

13. The ETC makes no ATP directly!
The ETC releases energy in a step-
wise series of reactions
It powers ATP synthesis via oxidative
phosphorylation.
But it needs to be coupled with
chemiosmosis to actually make ATP.

14. Oxidative Phosphorylation
Production of ATP using
transfer of electrons for energy
Some ATP is produced by substrate-level
phosphorylation during glycolysis and the
Krebs cycle, but most comes from
oxidative phosphorylation

15. Oxidative phosphorylation
 CONCEPT :
 During oxidative phosphorylation,
chemiosmosis couples electron transport to
ATP synthesis

16. Chemiosmosis
 The Energy-Coupling Mechanism
 Inner membrane of mitochondria has many
protein complexes called ATP synthase
◦ ATP synthase – enzyme that makes ATP from
ADP and inorganic phosphate
It uses the energy of an existing gradient to
do this.

17. The existing gradient is the difference in
H+ ion concentration on opposite sides of
the inner membrane of the mitochondria
Inner
Mitochondrial
Oxidative
Glycolysis phosphorylation. membrane
electron transport
and chemiosmosis
ATP ATP ATP
H+
H+
H+
H+
Protein complex Cyt c
Intermembrane
of electron
space
carners
Q IV
I III
ATP
Inner II synthase
mitochondrial FADH2
FAD+ 2 H+ + 1/2 O2
H2O
membrane
NADH+
NAD+ ADP + Pi ATP
(Carrying electrons
from, food) H+
Mitochondrial Electron transport chain Chemiosmosis
matrix Electron transport and pumping of protons (H +), ATP synthesis powered by the flow
which create an H+ gradient across the membrane Of H+ back across the membrane
Oxidative phosphorylation

18. Chemiosmosis
 Chemiosmosis – the process in which
energy stored in the form of a hydrogen ion
gradient across a membrane is used to
drive cellular work (like the synthesis of
ATP)

19.  It is the job of the ETC to create this H+
ion gradient
Inner
Mitochondrial
Oxidative
Glycolysis phosphorylation. membrane
electron transport
and chemiosmosis
ATP ATP ATP
H+
H+
H+
H+
Protein complex Cyt c
Intermembrane of electron
space carners
Q IV
I III
ATP
Inner II synthase
mitochondrial FADH2
FAD+ 2 H+ + 1/2 O2
H2O
membrane
NADH+
NAD+ ADP + Pi ATP
(Carrying electrons
from, food) H+
Mitochondrial Electron transport chain Chemiosmosis
matrix Electron transport and pumping of protons (H+), ATP synthesis powered by the flow
which create an H+ gradient across the membraneOf H+ back across the membrane
Oxidative phosphorylation

20. H+ ions are pumped into the
intermembrane space by the ETC
The H+ ions want to drift back into the
matrix.
But they can only come into the matrix
easily through ATP synthase channels

21. A protein complex, ATP
synthase, in the cristae
actually makes ATP from
ADP and Pi.
ATP used the energy of
an existing proton gradient
to power ATP synthesis.
proton gradient
develops between the
intermembrane space
and the matrix.

22. Mitochondrial redox carrier
NADH Complex I Q Complex
III
Complex II
Complex IV
FADH
O2

23. 4 Complexes
 proteins in specific order
 Transfers 2 electrons in specific order
◦ Proteins localized in complexes
 Embedded in membrane
 Ease of electron transfer
◦ Electrons ultimately reduce oxygen to
water
 2 H+ + 2 e- + ½ O2 -- H2O

24. Complex I
 Has NADH binding site
◦ NADH reductase activity
 NADH - NAD+
◦ transfers to electron carriers
◦ NADH (nicotinamide adenine
dinucleotide )

25. Passes them to coenzyme Q ( Ubiquinone )
Also receive electron from complex II

26. Complex II
 succinate ---FAD—ubiquinone
◦ Contains coenzyme Q
◦ FADH2 binding site
 FAD reductase activity
 FADH2 -- FAD
 conversion of succinate to fumerate

27. Mitochondrial redox
carriers

28. Complex III
 ubiquinone - ubiquinone
 while cytochrome C gets reduced
 Also contains cytochromes b
 NADH generates more energy than
FADH2

29. Complex IV
 reduction of oxygen
 cytochrome oxidase
 oxygen ---> water
◦ 2 H+ + 2 e- + ½ O2 -- 2 H2O
◦ transfers e- one at a time to oxygen

30. ATP Produced
◦ The NADH from glycolysis may also
yield 3ATP.
 Krebs cycle can be used to generate
about 2ATP.
 Electron transport chain yield 32 ATP.

31. ATP Produced
 About 40% of energy glucose molecule
transferred to ATP during cellular respiration
 Makes approximately 38 ATP.

32. Conclusion /Result
OVERALL yield from
glucose 36-38 ATPs

33. THANK YOU
GROUP -3
SHAH SUNIL KUMAR
GIRI JEMY
TIMILSINA BINOD
MAJHI INDRA
ABDHIKINI
WARSAME
MOHAMMAD ABDIKALI