Ch. 8: Harvesting Energy Glycolysis & Cellular Respiration Case Study Athletes Boost Counts.pdf http://www.sumanasinc.com/webcontent/animations/content /cellularrespiration.html - CR Intro 8.1: How Do Cells Obtain Energy? photosynthesis ultimate source of energy. photosynthetic organisms capture sun’s energy and store it in form of glucose 6 CO2 6 H2O light energy C6H12O6 6 O2 nearly ALL organisms use glycolysis & cellular respiration to break down sugar and capture the released energy as ATP C6H12O6 6 O2 6 CO2 6 H2O ATP energy heat energy cells break down glucose in 2 stages glycolysis liberates a small quantity of ATP cellular respiration produces a lot of ATP Figure 8-1 Photosynthesis provides the energy released during glycolysis and cellular respiration energy from sunlight photosynthesis 6 CO2 6 H2O 6 O2 cellular respiration C6H12O6 glycolysis ATP 8.1: How Do Cells Obtain Energy? Glucose is a key energy-storage molecule all cells metabolize glucose plants covert glucose sucrose or starch humans & many other animals store energy in glycogen & fat glycogen starch 8.2: What Happens During Glycolysis Glycolysis (“sweet”, “split apart”): series of enzyme catalyzed reactions that splits 6-C glucose into 2 molecules of pyruvate Energy investment stage: 1 glucose + 2 ATP 1 fructose bisphosphate Energy harvesting stage: fructose bisphosphate 2 G3P pyruvate 2 ATP generated from each G3P but 2 were used to form fructose bisphosphate (net gain ATP = 2/glucose) 2 G3P donates 2 e- & a H+ ion to NAD+ NADH Glycolysis https://www.youtube.com/watch?v=hDq1rhUkV-g – Glycolysis video https://www.youtube.com/watch?v=EfGlznwfu9U – CR Rap Ch. 8.3: What Happens During Cellular Respiration Cellular respiration: breaks down 2 pyruvate molecules into 6CO2 & 6 H2O and produces 32 ATP in the mitochondria https://www.youtube.com/watch?v=pOfyuoa0Ywc – Mitochondria structure 3 stages of cellular respiration 1. Pyruvate prep-step & Krebs cycle 2. ETC 3. Chemiosmosis 1a- Pyruvate Prep Step pyruvate (synthesized in cytosol during glycolysis) is actively transported into matrix Formation of acetyl CoA (2C acetyl + coenzyme A): a. pyruvate splits releasing CO2 and leaves behind an acetyl group b. acetyl group reacts with CoA acetyl CoA c. transfers liberated energy to NAD+ NADH 1b – Krebs Cycle or Citric Acid Cycle a. Acetyl CoA + 4C molecule 6C citrate (citric acid) molecule b. Acetyl CoA released and recycled 2 pyruvate generates (mitochondrial matrix reactions) c. Enzymes break down acetyl group CO2 + 4C molecule d. chemical energy captured in NADH, FADH2, ATP 2 ATP, 8 NADH, 2 FADH2 & 6 CO2 Formation of acetyl CoA coenzyme A NADH NAD CO2 e. CO2 becomes a waste product FADH2 coenzyme A acetyl CoA NAD FAD Krebs cycle NADH ADP ATP Krebs Cycle or Citric Acid Cycle https://www.youtube.com/watch?v= JPCs5pn7UNI - Krebs Song 2 - ETC series of electron transporting molecules embedded in inner mitochondrial membrane (matrix) Donate e- & ADP P 1 H2O per 2 e- H+ FADH2 NADH NAD ETC Energy either 1-lost as heat 2-pumps in H+ ATP synthase FAD (inner membrane) (intermembrane space) ATP https://www.youtube.com/watch?v= xbJ0nbzt5Kw – ETC Video http://www.nclark.net/ElectronTrans portChain.mp3 - ETC Song Boosting Blood Counts: Do Cheaters Prosper? When people and other animals exercise vigorously, they are unable to get enough air into their lungs, enough oxygen into their blood, and enough blood circulating to their muscles to allow cellular respiration to meet all their energy needs. As oxygen demand exceeds oxygen supply, muscles must rely on glycolysis (which yields far less ATP than does cellular respiration) for periods of intense exercise. This explains why some athletes, desperate for a competitive edge, may turn to illegal blood doping to increase the ability of their blood to carry oxygen . https://screen.yahoo.com/tyler-hamilton-blood-doped-162214802.ht - Tyler Hamilton (Armstrong teammate) 3 - Chemiosmosis Chemiosmosis: process by which energy is used to generate a concentration of H+ to generate ATP https://www.youtube.com/watch?v=3y1dO4nNaKY ATP synthase carrier proteins transport 1. ATP : matrix intermembrane space 2. ADP : intermembrane space matrix ATP molecules diffuse through large pores in outer mitochondrial membrane and into cytosol a person produces, uses, and then regenerates the equivalent of roughly his or her body weight of ATP daily Chemiosmosis yields 32 ATP Why is Cyanide So Deadly? common murder weapon where victims of the poison die almost instantly blocks the last protein in the ETC which is an enzyme that combines electrons with oxygen if energy-depleted electrons are not carried away by oxygen, they act like a plug preventing high energy electrons from traveling the ETC no more H+ can be pumped across membrane and therefore, no chemiosmosis can kill within a few minutes STEPS INPUT OUTPUT Glycolysis 1 glucose 2 ATP 2 NAD 2 pyruvate 4 ATP 2 NADH 2 pyruvate 2 NAD+ 2 acetyl groups 2 NADH 2 CO2 Pyruvate Prep Step Krebs Cycle ETC TOTALS 2 acetyl 2CoA 6 NAD+ 2 FAD 2 CoA 6 NADH 2 FADH2 4CO2 2 ATP 8-10 NADH 2 FADH2 (1/2 O2) 8-10 NAD+ 2 FAD 6H2O 32 ATP Glucose (+ O2) 6 CO2 6H2O http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html - CR Review https://www.youtube.com/watch?v=00jbG_cfGuQ – Crash Course in ATP and Respiration NET GAIN 2 ATP 2 CO2 4 CO2 2 ATP 32 ATP 36 ATP Cellular Respiration Can Extract Energy from a Variety of Molecules Glucose sucrose, starch, protein & fat can enter CR stages and be broken down to produce ATP ATP not used for long term storage b/c it becomes unstable Fats stable and store 2X as much energy for their weight as carbs Candy bar (sucrose) glucose + fructose (metabolized in liver) G3P If cells have plenty of ATP some G3P diverted from CR to make glycerol. Excess acetyl CoA used to make fatty acids https://www.youtube.com/watch?v=EwqNp9cO_-4 – Why Can You Get Fat by Eating Sugar? 8.4 What Happens During Fermentation? glycolysis – used by virtually all organisms earlier life forms appeared under anaerobic conditions (no O2) existing before photosynthesis some organisms lack enzyme for cellular respiration and rely solely on fermentation while others live in places with little to no O2 - stomachs and intestines of animals - deep in soil, bogs, etc 2 types of fermentation a. lactic acid fermentation: pyruvate lactic acid b. alcoholic fermentation: pyruvate ethanol & CO2 fermentation allows NAD+ to be recycled when O2 is absent production of NAD+ is necessary for glycolysis to continue does not produce an ATP Lactic Acid Fermentation NO O2 = muscles stop muscles rely on glycolysis for 2 ATP/glucose molecule muscle cells ferment resulting pyruvate to lactate using e- & H+ from NADH microorganisms milk to yogurt, https://www.youtube.com/watch?v=LDh1O4Zk7Xc – Fermentation Video sour cream, cheese Figure 8-8 Glycolysis followed by lactic acid fermentation 2 NAD 2 NADH 2 NADH (glycolysis) 2 ADP 2 NAD (fermentation) 2 pyruvate 1 glucose 2 ATP 2 lactate Blood Doping: Do Cheaters Prosper? Why is the average speed of the 5,000-meter run in the Olympics slower than that of the 100-meter dash? During the dash, runner’s leg muscles use more ATP than cellular respiration can supply. But anaerobic fermentation can only provide ATP for a short dash. Longer runs must be aerobic, and thus slower, to prevent lactic acid buildup from causing extreme fatigue, muscle plain, and cramps. Sprinters rely on lactic in their leg muscle cells for speed. acid fermentation their final burst of https://www.youtube.com/watch?v=DGq94gpKEbg – Lactic Acid and Fatigue Alcoholic Fermentation? many microorganisms like yeast engage in alcoholic fermentation under anaerobic conditions https://www.youtube.com/watch?v=4SosPuWAg7g Making ginerale generates alcohol and CO2 from pyruvate like in lactic acid fermentation, NAD+ must be regenerated to allow glycolysis to continue 2 NAD 2 NADH 2 NADH (glycolysis) 2 pyruvate ADP NAD (fermentation) 1 glucose 2 2 2 ATP 2 ethanol 2 CO2 Blood Doping: Do Cheaters Prosper? Although runners who do the 100-meter dash rely heavily on lactic acid fermentation to supply ATP, long distance athletes including cyclists, marathon runners, and cross-country skiers must pace themselves. They must rely on aerobic cellular respiration for most of the race, saving the anaerobic spring for the finish. Training for distance events focuses on increasing the capacity of the athletes’ respiratory and circulatory systems to deliver enough oxygen to their muscles. Blood doping most often occurs among distance athletes seeking to increase the oxygen carrying capacity of their blood so that cellular respiration can generate the maximum amount of ATP from glucose. The EPO-mimicking drug CERA – that the disgraced cyclist Ricco now admits having taken –helped keep his muscles supplied with ATP by stimulating overproduction of oxygen-carrying red blood cells. In the particularly demanding mountain stages of the Tour de France, which Ricco won, his clean competitors were at a disadvantage because their leg muscles became painfully laden with lactate from fermentation sooner than Ricco’s did. Blood Doping: Do Cheaters Prosper? Because EPO is produced naturally in the human body, its abuse is hard to detect. CERA, developed for use by people with anemia (who have too few red blood cells), was new on the market at the time of the 2008 Tour de France, and Ricco may have assumed it would be undetectable. But CERA’s manufacturer, the pharmaceutical firm Hoffman-La Roche, had provided samples of the drug to the World Anti-Doping Agency before it was marketed, allowing researchers to develop urine tests to identify users. This led to Ricco’s exposure and disgrace, and his team’s devastating disappointment. 1. Some athletes move to high-altitude locations to train for races run at lower altitudes because the low oxygen levels at high altitudes stimulate increased production of red blood cells. Is this cheating? Explain your reasoning. 2. Advances in gene therapy may one day make it possible to modify athletes’ cells so that they have extra copies of the gene that produces EPO. Is this cheating? Explain your reasoning.