Cellular respiration Flashcards
Electron shuttles
NADH & FADH2
Cellular respiration overall process
- Organic compounds+O2 -> CO2 + H2O + energy.
- Energy released as electrons go from organic compounds to O2
- C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy (ATP + heat)
- Oxidation C6H12O6 -> 6 CO 2
- Reduction: 6 O2 -> 6 H2O
Overview of cellular respiration
- Glycolysis.
- Oxidation of pyruvate.
- Krebs cycle
- ETC & oxidative phosphorilation
Overview of glycolysis #1
In cytoplasm.
glucose -> 2x pyruvate (3 carbons) + 2ATP + 2NADH
Overview of oxidation of pyruvate #2
Mitochondria.
pyruvate -> acetyl CoA + 2O2 + NADH
per glucose 2 acetyl CoA + 2 O2 + 2NADH
Overview of Krebs cycle #3
Mitochondrial matrix.
Acetyl CoA + 2 CO2 + ATP + 3 NADH + FADH2
per glucose 4 CO2 + 2 ATP + 6 NADH + 2 FADH2
Overview of ETC & oxidative phosphorilation
Inner mitochondrial membrane.
O2 driving force, electronegative.
30-32 ATP/glucose.
ATP production
- Oxidative phosphorylation (ATP synthase): ADP + Pi = ATP
- 85% of cellular ATP (26-28 moles) - Substrate level phosphorylation: substrate-phosphate + ADP -> ATP + product
- glycolysis and the Krebs cycle
Phases of glycolisis #1
Energy requiring & energy producing (4 ATP & 2 NADH).
Energy requiring glycolysis (1)
- Glucose -> 2x glyceraldehyde-3-phosphate.
- ATP hydrolized & phosphorylated intermediate.
- 2ATP:glucose-> glucose-6-phosphate (step #1)
- fructose 6-phosphate -> fructose 1,6-bisphosphate (step #3)
Energy producing glycolysis (2)
Glyceraldehyde 3-phosphate -> pyruvate.
1. 4ATP: substrate level phosphorylation
1,3-bisphosphate -> 3phosphoglycerate (step 7)
phosphoenolpyruvate -> pyruvate (3C)
2. NADH: glyceraldehyde-3-phosphate -> 1,3-bisphosphoglycerate (step 6)
Net glucose: 2ATP (final - what we put in), 2 NADH, 2 pyruvate
Oxidation of pyruvate to AcetylCoA #2
Pyruvate is transported into the mitochondria.
pyruvate -> CO2 + NADH + AcetylCoA (CoA: coenzyme A)
Krebs cycle function #3
Oxidizes AcetylCoA to CO2
Complete oxidation of glucose requires two turns of the cycle
Krebs cycle: electrons are passed to..
a. NAD+ ➡️NADH (steps 3,4,8) isocitrate ➡️ alpha-ketoglutarate alpha-ketoglutarate ➡️succinyl CoA malate ➡️ oxaloacetate b. FAD ➡️ FADH2 (step 6) succinate ➡️ fumarate
Krebs cycle: ATP is produced (step 5)
succinyl CoA ➡️ succinate
GTP ➡️ GDP, ADP-ATP
Electron transport chain is comprised of:
- 4 multiprotein complexes (integral membrane proteins)
- 2 mobile electron carriers (shuttles, electrons drop in free energy as they travel down chain)
What does the Electron Transport Chain generate?
A proton gradient which is used to produce ATP (does not do it directly, it provides the potential energy)
NADH steps in ETC (1-3)
- Complex I receives electrons form NADH, pumps protons from the mitochondrial matrix into the intermembrane space.
- Ubiquinone receives electrons from Complex I: non protein that moves in lipid bilayer.
- Complex III receives electrons from Coenzyme Q: comprised of cytochromes, containing copper. pumps protons from the mitochondrial matrix into the intermembrane space.
NADH steps in ETC (4-6)
- Cytochrome receives electrons from Complex III (mobile carrier)
- Complex IV (cytochrome oxidase) receives electrons from cytochrome C: contains a heme prosthetic group containing copper. Pumps protons from the mitochondrial matrix into the intermembrane space.
- Electrons are transferred to oxygen producing water: produce and electrochemical gradient.
FADH in ETC
Lower free energy, electrons are at a lower energy point.
Complex 2➡️ubinquinone.
