1. Government Degree College Bijbehara Department of Botany Prof Burhan Ahad
Semester IV Topic : Electron Transport Chain (Cellular Respiration)

2. Brief Introduction of Respiration
Biological process whereby the energy stored in carbohydrates from PS is released in a step-wise, controlled manner.
Energy released is coupled to the synthesis of ATP.
ATP is essential for plant cell maintenance, growth and development

3. Cellular respiration a metabolic pathway of redox reactions:
-oxidation – loss of electrons
dehydrogenations: loss of hydrogen e-’s
-reduction - gain of electrons
gain on hydrogen e-’s
Oxidized molecules actually loose a hydrogen atom (1 electron, 1 proton)
Both the protons and electrons are used by cellular respiration to produce ATP

4. 3 Stages of Respiration Glycolysis TCA Cycle Electron Transport Chain
cytoplasm
with or without oxygen present
breaks glucose (6C) into 2 pyruvates (3C)
TCA Cycle
mitochondrial matrix
only if oxygen present
converts pyruvate via acetyl CoA into CO2; generates NADH and FADH2
Electron Transport Chain
mitochondrial membranes = cristae
transfers electrons from NADH and FADH2 to reduce O2 to H2O and generate ATP

5. Glycolysis Glucose (6C) 2 Pyruvate (3C) Ethanol Lactate TCA Cycle CO2
-O2 -O2
+O2
Ethanol Lactate
TCA Cycle

6. TCA cycle

8. Electron Transport Chain
During respiration, high energy electrons are passed along chains of molecules - Electron Transport Chains
Energy is released as molecules in the electron transport chains are oxidized
The energy released is used to power the production of ATP

9. Electron Transport System
NADH and FADH2 e- H+
ATP e- H+
4e- + 4H+ + O2 2H2O
cyt. oxidase

10. Stage 3: Electron Transport Chain
The electron transport chain (ETC) is a series of membrane-bound electron carrier molecules called cytochromes
embedded in the mitochondrial inner membrane
electrons from NADH and FADH2 are transferred to cytochromes of the ETC
each cytochrome transfers the electrons to the next cytochrome in the chain

13. Stage 3: Electron Transport Chain
Energy from the Electrons
As the electrons are transferred, some electron energy is released with each transfer
This energy is used by the cytochromes to pump protons (H+) across the membrane from the matrix to the inner membrane space

14. Stage 3: Electron Transport Chain
Energy from the Protons
Electron energy is used by the cytochromes to pump protons (H+) across the membrane from the matrix to the inner membrane space
A proton gradient is established
There are more protons on the

15. Stage 3: Electron Transport Chain
The cytochromes are channel proteins and use the electron energy to pump protons (H+) across the inner mitochondrial membrane
Now there are more protons on the inside of the membrane than the outside
A proton gradient is established
This proton gradient is potential energy that can be utilized to make more ATP’s
Recall diffusion: The protons want to equalize their number on both sides of the membrane

16. Stage 3: Electron Transport Chain

17. Stage 3: Electron Transport Chain
There are other channel proteins in the membrane known as ATP synthases
ATP synthases provide a channel for the protons to diffuse through
The rushing protons provides the energy for ATP synthase to phosphorylate ADP to ATP

20. Animation OF ETC

22. Stage 3: Electron Transport Chain
In Aerobic Respiration, oxygen is the final molecule to receive the hydrogens as they are passed down the Electron Transport Chain
The result is water: O2 + 4e- + 4H H2O
Oxygen is reduced to water
Oxygen is the Final Electron Acceptor in Aerobic Respiration