The document discusses biological oxidation and reduction processes, including electron transfer in redox reactions and the role of metabolic pathways. It explains the mechanisms of electron transport chains within mitochondria, detailing the functions of various protein complexes involved in ATP synthesis. Additionally, it covers standard reduction potentials and the relationship between free energy changes and electron transfer.

1. BIOLOGICAL
OXIDATION AND
REDUCTION
BY;
WISHAL
BUTT

2. OXIDATION
• Loss of electrons by an atom,
ions or molecule during a
chemical reaction & increase
its oxidation state.

3. REDUCTION
• Gain of electrons by an
atom , ion or molecule
during a chemical reaction
& decrease in its oxidation
state

4. REDOX REACTIONS
• The reactions which involves
both reduction process &
complementary oxidation
process called redox reaction.

5. EXPLANATION
1. Transfer of phosphoryl group
2. Electron transfer ( redox)
3. Flow of e⁻ is responsible for all work done by the
organism
4. In nonphotosynthetic organisms source of electrons is
food
5. In photosynthetic organism initial e⁻ donor is a
chemical specie excited by absorption of light.
6. Metabolic pathway is complex
7. Electrons metabolic intermediates e⁻ carrier
acceptor having high e⁻ affinity with release of energy

6. HALF REACTIONS
• Reaction;
• Fe⁺ᴵᴵ + Cu⁺ᴵᴵ Fe⁺ᴵᴵᴵ + Cu⁺
• Two half reactions;
• Fe⁺ᴵᴵ Fe⁺ᴵᴵᴵ + e⁻
• Cu⁺ᴵᴵ + e⁻ Cu⁺
• Fe⁺ᴵᴵ & Fe⁺ᴵᴵᴵ
• Reductant – oxidant pair
• e⁻ donor e⁻ + e⁻ acceptor
• Fe⁺ᴵᴵ is electron donor
• Fe⁺ᴵᴵᴵ is electron acceptor

7. EXAMPLE:
oxidation of reducing sugar:
RCHO + 4OH⁻ 2 Cu⁺ᴵᴵ RCOOH
+ Cu₂O + H₂O

8. OXIDATION INVOLVE DEHYDROOGENATION
Alkane to alkene:
C₂H₄ - CH= CH-
oxidation takes place due to the loss of
hydrogen atom.

9. ELECTRON TRANSFER WAYS
1.Directly as electrons
2.As hydrogen atom
3.As hydride ion
4.Direct combination with
oxygen

10. ELECTRON TRANSPORT CHAIN
1.Glucose metabolize & give
CO₂ plus H₂O.
2.NAD⁺ & FAD are converted to
NADH & FADH₂
3.Down the chain energy
decreases

12. MITOCHONDRION
ETC is present in the inner
mitochondrial membrane.
electron trans port and ATP
synthesis occurs continuously in
all cells having mitochondria.

13. 1. STRUCTURE;
Inner membrane
Impermeable
ATP, ADP , pyruvate
Carriers
Rich in proteins
used in electron transport
& oxidative Phosphorylation.
cristae

14. 2. ATP SYNTHASE COMPLEX
* Protein complexes reffered as inner membrane
particles.
* Attached on inner surface
• Appear as sphere
3. MATRIX;
* Gel like soln. 50% protein
* Enzymes for oxidation of pyruvate , aa, fatty acids, &
carboxylic acid cycle.
* Urea & heme
* NAD⁺, FAD, ADP, Pi

15. ORGANIZATION OF CHAIN

16. REACTIONS OF ETC
All members are proteins except
coenzyme Q.
Works as enzyme e.g.
dehyrogenase
Iron as iron sulfur center,
Prophyrin ring as in cytochromes
contain copper as in cytochrome a
+a₃ complex.

17. 1. FORMATION OF NADH
NAD⁺ reduce to NADH by Dehydrogenases that remove
two H- atoms from substrate hydride ion transform
NAD⁺ to NADH & a free proton H⁺

18. 2. NADH DEHYDROGENASE
* H⁺ & hydride ion carried by NADH transfer to NADH dehydrogenase, an enzyme
complex ( complex 1).
* complex-1 has FMN accepts two H⁺ & changes into FMNH₂.
* NADH dehydrogenase has Fe-atoms paired with S-atoms in Fe-S center necessary to
transfer H-atom to next member.

19. 3.COENZYME Q;
* Quinone derivative, having long isoprenoid tail, called
ubiquinone because it is ubiquitous in biological system.
* accept H-atom both from FADH₂ & FMNH₂.

20. 4.CYTOCHROMES;
* Remaining members of ETC are cytochromes .
* Having heme group made up of prophyrin ring
containing an iron atom.
* reversibly converted from its ferric to ferrous
form. Is its function.
* Electrons passed along the chain from
coenzyme Q cytochrome b & c
cytochrome a + a₃ .

21. 5. CYTOCHROME A + A₃;
* Only electron carrier in which heme iron
has free ligand , react directly with
molecular oxygen.
* here transported e⁻, molecular oxygen, &
free protOn are brought togather to produce
H₂O.

23. 6. SITE-SPECIFIC INHIBITORS;

24. ENERGY RELEASE;
* Energy releases when e⁻ moves
along the ETC, from e⁻-donor, to e⁻-
acceptor.
1.REDOX PAIR;
oxidation of one comp. is always
compensated by reduction of second
one.
e.g.
NADH NAD⁺
accoumpained by

25. 2. STANDARD REDUCTION POTENTIALS;
 The standard reduction
potential is the tendency for a
chemical species to be
reduced, and is measured in
volts at standard conditions.
The more positive the
potential is the more likely it
will be reduced.
 For redox pairs it is listed
from more –ve E₀ +ve
E₀.
 More –ve the value , greater
tendency of reductant to give e⁻.
 More +ve the value , greater

26. 3. ΔG & ΔE₀;
ΔG = -nFΔE₀
Change in free energy is directly related to
the magnitude of the change in E₀.
n = no. of electron transferred.
F = Faradays constant.
ΔE₀ = E₀ of electron accepting pair - E₀ of
electron donating pairs.
ΔG = change in standard free energy.

27. REFERENCES;