How Cells Harvest Chemical Energy Introduction to Cell Metabolism Glycolysis Aerobic Cell Respiration Anaerobic Cell Respiration
Breathing and Cell Respiration are related O2 CO2 BREATHING Lungs Muscle cells CO2 Bloodstream O carrying out 2 CELLULAR RESPIRATION Sugar + O2 → ATP + CO2 + H2O
Cellular Respiration uses oxygen and glucose to produceCarbon dioxide, water, and ATP.Glucose Oxygen gas Carbon Water Energy dioxide
How efficient is cell respiration? Energy released Energy released Gasoline energy from glucose from glucose converted to (as heat and light) banked in ATP movement 100% About 40% 25%Burning glucose “Burning” glucose Burning gasolinein an experiment in cellular respiration in an auto engine
Reduction and Oxidation OILRIGOxidation is losing electronsReduction is gaining electrons Loss of hydrogen atoms Energy Glucose Gain of hydrogen atomsGlucose gives off energy as is is oxidized
Reduction and Oxidation OILRIG Gain or loss of electrons is often in the form ofhydrogen. The hydrogen is then passed to a coenzyme suchas NAD+
Reduction and OxidationWhat are some common co-enzymes? NAD+ and FAD NAD+ + 2 H ⇒ NADH + H+ FAD + 2H ⇒ FADH2 Remember that H =2 electrons and 2H+
Reduction and OxidationThese co-enzymes are very important for cellrespiration because they transfer high-energyelectrons to electron transport systems (ETS).
Reduction and Oxidation As the electrons move from carrier to carrier, energy is released in small quantities.Electron transport system(ETS)
Generation of ATPThere are two ways to generate ATP Chemiosmosis Substrate-Level Phosphorylation
Generation of ATPChemiosmosisCells use the energyreleased by “falling”electrons in the ETS topump H+ ions across amembraneUses the enzyme ATPsynthase.
General Outline Glucose Glycolysis Oxygen No Oxygen Pyruvic Acid Aerobic Anaerobic Transition Reaction Fermentation Krebs Cycle ETS 36 ATP
Fermentation Requires NADH generated by glycolysis. Where do you suppose these reactions take place? Yeast produce carbon dioxide and ethanol Muscle cells produce lactic acid Only a few ATP are produced per glucose