This document discusses oxidation-reduction (redox) reactions in living organisms:
1. Redox reactions involve the transfer of electrons and are essential to photosynthesis and cellular respiration. Photosynthesis uses redox reactions to convert sunlight into chemical energy, while cellular respiration uses redox to break down glucose and release energy.
2. Cellular respiration and photosynthesis both rely on redox reactions to transfer electrons between molecules. Electron carriers like NAD+ and FAD shuttle electrons between reactions to release energy.
3. The movement of electrons from higher-energy states to lower-energy states, as electrons are passed to more electronegative atoms like oxygen, drives ATP production in cellular respiration. Redox reactions
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.
11.
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,
16.
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.
