6Cellular Respiration may be: Anaerobic: doesn’t require oxygenAerobic: requires oxygen
7Anaerobic Respiration Makes a small amount of usable energy without using oxygenReactions occur in cytoplasmProduces 2 ATP per glucose molecule
8Takes place in yeast, and bacteria Can also occur in human muscle cells if no oxygen is present.
9Anaerobic Respiration Glycolysis: (sugar is “split”)Glucose is only partially broken downNot all of it’s stored energy is releasedC6H12O ATP → 2 pyruvic acid ATP(6-carbon) (3-carbon)Net gain of energy is 2 ATPAre producedNeeded to start
12What happens to Pyruvic Acid? Fermentation of Alcohol(Oxygen not present)C6H12O6 → Ethyl Alcohol + CO2 + 2ATPHappens in YeastPyruvic acid (from split glucose) is turned into ethyl alcohol and CO2 (carbon dioxide)
13Useful in the brewing and baking industries Produces alcoholProduces carbonationBubbles of CO2 make bread rise
14What happens to Pyruvic Acid? Fermentation of Lactic Acid:(Oxygen not present)C6H12O6 → Lactic Acid + 2ATPHappens in some bacteriaPyruvic acid (from split glucose) becomes lactic acidUsed to make cheese, yogurt and buttermilk
16Let’s Try This Activity: Finger “Crunches” As fast as possible crunch your fingers 100 times
17Lactic Acid buildup in human muscle cells During intense exercise, if oxygen is not present, human muscle cells use anaerobic respiration to produce some energy, yielding lactic acidLactic acid builds upMuscles eventually cramp up (burning feeling)
18Oxygen Debt:Eventually Lactic acid goes to your liver where it is changed back into glucose which can be used again.In order to convert the lactic acid, your body needs oxygen
25Aerobic Respiration Makes more ATP using oxygen Occurs in mitochondria Most eukaryotic organisms carry out aerobic respirationPlants also carry out respiration!!!
26Glucose gets completely broken down to release energy Releases more energy than anaerobic respiration (more energy efficient)Most of the CO2 and H2O you exhale is produced from aerobic respirationC6H12O6 + O2 → CO2 + H2O + 36 ATP
283 Steps of Aerobic Respiration Step 1: GlycolysisSame as in anaerobic respirationDoesn’t require oxygenTakes place in cytoplasmGlucose is split producing 3-carbon pyruvic acidAlso produces NADH from NAD+This “carries” some high energy electrons and H+Net production of 2 ATP
30Step 2: Kreb’s Cycle (Citric Acid Cycle) Requires oxygenPyruvic acid from glycolysis enters mitochondriaReactions occur in mitochondrial matrixProduces high energy electron/hydrogen carriersNADH and FADH2 (called coenzymes)These molecules carry “H+” and high energy electronsThese will be used later to help produce more ATPProduces CO2 gasProduces 2 ATP
32Step 3: Electron Transport Chain Requires oxygenOccurs on inner membrane of mitochondriaUses high energy electrons and H+ to convert ADP to ATPUses the NADH/FADH2 from glycolysis & Krebs cycleFinal electron & hydrogen acceptor is oxygen (which then becomes H2O which is released)Produces 32 ATP!!!Produces H2O
33Animation of Electron Transport Chain Note that Oxygen is the final electron acceptor and accepts 2 H+ to become water!
35Anaerobic PhaseDoesn’t need O2Aerobic PhaseNeeds O2
36Efficiency of Cellular Respiration Anaerobic: Yields 2 ATP per glucoseEnd products of fermentation still contain a lot of unused potential energyMeets energy needs of simple organismsAerobic: Yields 36 ATP per glucoseMore efficient45% of the energy available in glucose is transferred to ATP where it can do further work for the cellNote: Car engines only converts about 25% of the energy from gasoline
37Respiration of Fats and Proteins Get broken down and converted into amino acids, glycerol and fatty acidsThese can enter respiration pathway at different pointsFats yield twice as much ATP as glucoseProteins yield about the same as glucose but are not the preferred energy source for the cell
38Evolution of Cellular Respiration First life originated when there was hardly any oxygen in the atmosphere.(Probably prokaryotes with few organelles and nomitochondria)Glycolysis was the first biochemical process to evolveHappens in cytoplasm and no oxygen needed.
39Comparing Photosynthesis and Cellular Respiration How are these two processes related to each other?In a typical plant cell describe the way energy is obtained and utilized through both photosynthetic and respiration processes.Include the materials that need to be taken in and released