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REDOX reactions in respiration
Equations for aerobic respirationAll of these are fine!....
Equation for Cellular Respiration
6CO2 + 6H20 + e- + 36-38ATP
+ heat
C6H12O6 + 6O2
YIELDS
What are REDOX reactions in respiration?
• ‘REDOX’ means ‘oxidation and reduction’• You can’t have one without the other• REDOX reactions involve ELECTRON TRANSFER• Organic molecules contain lots of energy locked in
their covalent bonds• Redox reactions TRANSFER this bond energy in the
form of ELECTRONS to ELECTRON CARRIERS which can temporarily store it and move it to ultimately synthesise ATP
Energy metabolism and REDOX reactions
• REDOX (oxidation-reduction) reactions play a key role in energy flow through organisms
• This is because the electrons flowing from one molecule to another are carrying energy with them
REDOX reactionsOXIDATION REDUCTION
Loss of electrons Gain of electrons
Gain of oxygen Loss of oxygen
Loss of hydrogen Gain of hydrogen
Results in C-O bonds Results in C-H bonds
Results in a compound with lower potential energy
Results in a compound with higher potential energy
OIL RIGLEO says GER
REDOX reactions in respirationCells tap energy from electrons transferred from organic fuels to oxygen
Glucose gives up energy as it is oxidized: it transfers its electrons (and energy) to water
The protons follow the electrons to produce water
Loss of hydrogen atoms
Energy
Gain of hydrogen atoms
Enzymes remove electrons from glucose molecules and transfer them to a coenzyme
Hydrogen carriers such as NAD+ and FED shuttle electrons in redox reactions
OXIDATION
Dehydrogenaseand NAD+
REDUCTION
• NADH delivers electrons to a series of electron carriers in an electron transport chain
• As electrons move from carrier to carrier, their energy is released in small quantities
Redox reactions release energy when electrons “fall” from a hydrogen carrier to oxygen
Energy released and now
available for making ATP
ELECTRON CARRIERS
of the electron transport chain
Electron flow
Glycolysis: Always the initial stage of respiration
• Location: cytoplasm• Substrate: glucose• Requires input of 2 ATP• Products: pyruvate,
(NADH), 4 ATP Glycolysis is an anaerobic process: no oxygen required
the movie...
Summary of glycolysis
1. Occurs in the cytoplasm of the cell2. Two ATP molecules are used to start the process
(‘energy investment phase’)3. A total of 4 ATP’s are produced (net gain of 2 ATP)4. 2 molecules of NADH are produced5. Involves substrate level phosphorylation, lysis, oxidation
and ATP formation6. Controlled by enzymes: when ATP levels in the cell are
high, feedback inhibition will block the first enzyme in the pathway
7. Produces 2 pyruvate molecules at the end
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