This ppt describes redox reactions occurring in living organism

1. Ms. Uzma Irfan
Lecturer
The Department of Botany
The Women University Multan
Email: uzma.6370@wum.edu.pk
PLANT BIOCHEMISTRY
Lecture 2

2. OXIDATION-REDUCTION REACTION IN LIVING
ORGANISMS
PLANT BIOCHEMISTRY
BOT-510

3. CONTENT
Oxidation-Reduction Reaction in
Living Organism
Photosynthesis → Redox
process
Cellular Respiration → Redox
process

4. OXIDATION-REDUCTION REACTION IN LIVING
ORGANISMS
• Also known as Redox Reaction
• Involves the transfer of electrons
Oxidation is losing electron
Reduction is gaining electron
• LEO GER: loss of electron(Oxidation) & gain of electron(Reduction)

5. REDOX REACTIONS IN LIVING ORGANISMS
• Oxidation and reduction reactions in biological processes are
Cellular respiration and
Photosynthesis

6. PHOTOSYNTHESIS AS REDOX PROCESS
• Green plants carry out the redox
reaction
• Converts sunlight into chemical
energy
• Makes possible almost all life on
earth.

7. Glucose gives off energy as it is oxidized
CELLULAR RESPIRATION AS REDOX PROCESS
• This reaction, is simply a combustion reaction
• As gasoline in an engine
• Process is broken down into many smaller steps
• Energy of glucose is released in small bursts

8. THE GENERATION OF ATP
• Generated either by
Substrate level phosphorylation
Oxidative phosphorylation

9. THE GENERATION OF ATP
• Substrate level phosphorylation
• In these steps, a phosphate group is transferred from a pathway intermediate
straight to ADP, a process known as substrate-level phosphorylation.
C-C-C~P + ADP→C-C-C + ATP
• Two such phosphorylation occurs in Glycolysis &
• One in the Krebs cycle

10. THE GENERATION OF ATP
• Oxidative phosphorylation
• Many more steps
• Produce ATP in an indirect way.
• Electrons from glucose are transferred to electron carriers in electron transport
chain.
• As electrons move, go from a higher to a lower energy level
• Ultimately passed to oxygen (forming water).
• Energy released, powers production of ATP by ATP synthetase.

12. • Cellular respiration involves
 Reactions in which electrons are passed from one molecule to another.
 Known as oxidation-reduction reactions (or redox reactions),
• They play a central role in the metabolism of a cell.

13. ELECTRON CARRIERS
• Sometimes called Electron shuttles
• Organic molecules
• Readily cycle between oxidized and reduced forms
• Used to transport electrons during metabolic reactions.
Play particularly important roles during cellular respiration

14. ELECTRON CARRIERS
There are two electron carriers
• NAD+ (nicotinamide adenine dinucleotide) and
• FAD (flavin adenine dinucleotide).

15. REDOX REACTIONS WITH CARBON CONTAINING
MOLECULES
• Fundamentally about the transfer of electrons.
• In the context of biology,
“Gain or loss of H and O atoms as a proxy for the transfer of electrons.”
• As a general rule of thumb,
gains H atoms or loses O atoms →→→ Reduced (gained electrons)
loses H atoms or gains O atoms →→→ Oxidized (lost electrons)
• For example, let’s go back to the reaction for glucose breakdown,

17. IN CELLS UNDERSTAND THE ROLE OF MOVEMENT OF ELECTRONS
PLAYS IN ENERGY EXCHANGES
• In redox reactions,
• energy is released when an electron loses potential energy(PE) as a result of the
transfer.
• When electrons are associated with
less electronegative atoms (such as C or H) →→→ have more PE
more electronegative atom (such as O) →→→ have less PE

18. • Redox reaction that moves
Electrons or electron density from a less electronegative atom
A more electronegative atom
Will be spontaneous and release energy.

19. • The energy that's released, captured and used to do work.
• In cellular respiration
• Electrons from glucose move, passing to lower and lower energy states
• Releasing energy at each step.
• The goal of cellular respiration is to capture this energy in the form of ATP.

20. ELECTRONS & ENERGY

21. WHAT'S THE POINT OFALL THIS REDOX?