Phase IV metabolism producing the primary source of cellular energy i.e., ATP

1. Cellular Energetics

2. Phase II
Phase III
Phase IV
Phase I
Digestion

3. ATP – Dynamic Energy Currency

4. • Bonds between phosphate groups in ATP
are called phosphoanhydride bonds
• These are highly unstable because of their
negatively charged phosphate groups,
which repel each other and strain the bonds
between them.
• It takes energy to make the phosphate
groups stay together, but when these bonds
are hydrolyzed, energy is released
ATP – Dynamic Energy Currency

5. ATP – ADP Cycle

6. Electron Transport Chain
&
Oxidative Phosphorylation

7. Electron Transport Chain

8. Components of ETC
1. Nicotinamide nucleotides
2. Flavoproteins
3. Iron – Sulfur proteins
4. Coenzyme Q
5. Cytochromes

9. Nicotinamide Nucleotides

10. Flavoproteins

11. Iron – Sulphur Proteins
• Iron sulfur proteins exist in the oxidized or
reduced state.
• FeS protein participates in the transfer of
electrons from FMN to Coenzyme Q,
Cytochrome b to C1

12. Coenzyme Q (Ubiquinone)
• Quinone derivative with a variable
isoprenoid side chain.
• Mammalian tissue contains 10 isoprenoid
units, hence called as Coenzyme Q10.
• It is a lipophilic electron carrier that act as
bridge between complex I,II & III.

13. Cytochromes
• Conjugated proteins containing heme
group.
• Iron in this heme group is alternatively
oxidized and reduced, thus helping in
transfer of electrons.
• Depending upon the type of heme present
and absorption spectrum they are classified
as a1, a3, b, c, c1.

14. Cytochromes
• Cytochrome c only protein which is towards
the outer side of inner mitochondrial
membrane and loosely bound.
• Cytochrome a & a3 contains copper along
with iron in heme and gets oxidized during
the transfer of electrons, and together called
as cytochrome oxidase as it is the only
cytochrome which gets direct contact with
oxygen.

15. Complexes in ETC

16. NADH Shuttle

17. NADH Shuttle

22. Inhibitors of ETC

23. Oxidative Phosphorylation

24. Electron transport chain
sets up an H+ gradient
(proton motive force).
Energy of the pmf is
harnessed to make ATP.
Chemiosmotic Hypothesis

25. Complex V – ATP Synthase

26. Oxidative phosphorylation
• Explained by rotary motor/engine driving
model or binding change model.
• α subunit: for the transfer of protons
• β subunit: for ATP synthesis
• γ subunit: rotates to get conformational
change in β subunit

27. Oxidative phosphorylation
• β subunit exists in three forms loose, tight
& open

29. Glucose
ATP

30. Inhibitors
• Atractyloside: ADP/ATP
antiporter
• Oligomycin:ATP synthase
Uncouplers
• DNP shuttles H+ across
inner membrane,
dissipates gradient
• CaCl2 stimulates oxidative
phosphorylation and ATP
production
Atractyloside
oligomycin
DNP
Ca2+
Inhibitors &
uncouplers