Cellular Respiration
The collection of metabolic reactions in cells the break down food molecules and use the liberated energy to synthesize ATP
Oxidation
Partial/ full loss of electrons
Reduction
Partial/ full gain of electrons
Glucose to CO2
Glucose is oxidized forming CO2
O2 to H2O
Reduced to H2O
How does Glucose get broken down
Glucose is broken down by dehydrogenases
- facilitate the transfer from food molecules to electron shuttle molecules
Glycolysis
Enzymes break down a molecule of glucose into 2 molecules of pyruvate
- synthesis some ATP and NADH
Pyruvate oxidation
Occurs in mitochondrial matrix
- decarboxylation to form CO2
- generates NADH
- uses Carrier CoA to carry remaining carbons to another cycle
Citric Acid Cycle
Still in mitochondrial matrix
1) oxidizes Acetyl CoA into Co2
2) transfers high energy electrons to shuttle molecules like NADH and FADH2
3) produce ATP by substrate level phosphorylation
Fate of Pyruvate
Glycolysis made some ATP but still holds a lot of energy in pyruvate
2 thing happens
1- fermentation( lacks o2)
2- aerobic respiration ( o2 present )
Fermentation
No o2, no ETC, no mitochondria
- pyruvate stays in cytosol
- doesn’t produce ATP
Ethanolic Fermentation
Converts the pyruvate into acyetylaldehyde then into ethyl alcohol
- recycles NADH and H+ into NAD + to give energy to glycolysis
Lactic Acid fermentation
Pyruvate is reduced to lactate in 1 step( no CO2)
- used in bacteria, fungi, and animal muscle cells
2 types of aerobic organisms
1- Obligate aerobe
- only uses respiration
2- Facultative aerobe
- prefers respiration but uses fermentation when necessary
Oxidative Phosphoration
- all energy in glucose is now in NADH and FADH2
- uses ETC coupled with chemiosmosis to extract potential energy and synthesize more ATP
ETC in aerobic respiration
Transfer of electrons from NADH and FADH2 to Oxygen
What do the 4 protein complexes do
Complex 1: NADH dehydrogenase
Complex 2: succinate dehydrogenase
Complex 3: cytochrome complex
Complex 4: cytochrome oxidase
Prosthetic groups
Used to transfer electrons along ETC
- redox active cofactors that alternate between reduction and oxidation states as the accept electrons and give them away
Process of oxidative phosphorylation
1) Electrons to ETC
- NADH to Complex 1( at high energy)
- FADH2 to complex 2( lower energy)
2) electrons move through ETC by redox reactions - energy is released by each transfer
- terminal acceptor is o2
3) energy is used to pump protons from matrix to intermembranes space
Which protein complexes are used to pump protons
Complex 1, CoEnzyme Q, and Complex 4 are proton pumps
How does o2 become the terminal electron acceptor
Accepts 2 low energy electrons from Complex 4 and 2H+ from solutions
Chemiosmosis in Aerobic Respiration
- The ETC does not directly synthesize ATP
- NADH released free energy as it passes electrons to O2
- used to pump protons into innermembrane space
- uses membrane potential to synthesize ATP
