Cellular Energetics

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Cellular Energetics

• By Liz and Christine

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Cell Respiration

• Glycolysis
• Net 2 ATP
• Pyruvate Oxidation
• CO2 produced
• Krebs Cycle aka Citric Acid Cycle
• 1 ATP made per each acetyl CoA
• Electron Transport Chain
• 32-34 ATP produced
• O2 is the final electron acceptor

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Glycolysis

• Anaerobic respiration
• Location cytosol
• Energy investment is endergonic
• Energy capture is exergonic
• Substrate level phosphorylation
• Reactant 1 glucose, 2 ATP, 2 NAD
• Product 4 ATP, 2 NADH, 2 Pyruvate (3C)
• Phosphofructokinase
• Allosteric regulation
• AMP and ADP stimulate
• ATP and citrate inhibit

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Glycolysis Fermentation

• Anaerobic respiration
• Bacteria and yeast
• Pyruvate (3C) ? ethanol (1C) CO2
• Animals and some fungi
• Pyruvate ? lactic acid
• Liver converts lactic acid back to pyruvate when
  O2 is available

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Pyruvate Oxidation and Krebs Cycle

• Location matrix
• Pyruvate Oxidation
• Reactant 2 Pyruvate, 2 NAD, 2 CoA
• Product 2 Acetyl CoA, 2 NADH, 2 CO2
• Krebs Cycle (per pyruvate)
• Substrate level phosphorylation
• Acetyl CoA oxaloacetate citric acid
• Regenerates oxaloacetate
• Net gain 1 ATP, 3 NADH, 1 ATP, 1 FADH, 2 CO2

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Electron Transport Chain

• Chemiosmosis
• Pump H into intermembrane to build up proton
  gradient
• ATP synthase pump H back into matrix
• Oxidative phosphorylation
• NADH? 3 ATP
• FADH2 ? 2 ATP
• Produce 32-34 ATP

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Photosynthesis

• Light-Dependent Reactions
• Solar energy? chemical energy
• ETC with photosystem I and II
• H2O light ? ATP NADPH O2
• Light-Independent Reactions
• Calvin Cycle or Carbon Fixation
• Sugar production reactions
• CO2 ATP NADPH? C6H1206 ADP NADP

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Light- Dependent Reactions

• Location thylakoid membrane
• ETC
• Proton gradient
• ATP synthase
• Cyclic photophosphorylation
• PS II (P680)
• Photolysis
• Release O2
• PS I (P700)
• Net 18 ATP, 12 NADPH, 6 O2
• Noncyclic photophosphorylation
• Only PSII, no NADPH

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Carbon Fixation/ Calvin Cycle

• Location stroma
• Rubisco
• 3 turns of carbon cycle 1 G3P
• 6 turns 1 C6H1206
• Regenerate RuBP, ADP NADP

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Adaptations

• C4
• PEP carboxylase fixes carbon
• Adaptation to hot, dry climates
• CAM
• Separate carbon fixation from Calvin cycle by
  time of day
• Open stomates at night