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Ch. 8: Harvesting Energy - Glycolysis & Cellular Respiration

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Presentation on theme: "Ch. 8: Harvesting Energy - Glycolysis & Cellular Respiration"— Presentation transcript:

1 Ch. 8: Harvesting Energy - Glycolysis & Cellular Respiration
- CR Intro Case Study Athletes Boost Counts.pdf

2 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

3 energy from sunlight photosynthesis C6H12O6 6 CO2 6 H2O 6 O2 cellular
Figure 8-1 Photosynthesis provides the energy released during glycolysis and cellular respiration energy from sunlight photosynthesis C6H12O6 6 CO2 6 H2O 6 O2 cellular respiration glycolysis ATP 3

4 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

5 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

6 Glycolysis – Glycolysis video – CR Rap

7 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 – Mitochondria structure 3 stages of cellular respiration Pyruvate prep-step & Krebs cycle 2. ETC 3. Chemiosmosis

8 Formation of acetyl CoA (2C acetyl + coenzyme A):
1a- Pyruvate Prep Step pyruvate (synthesized in cytosol during glycolysis) is actively transported into matrix Formation of acetyl CoA (2C acetyl + coenzyme 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

9 1b – Krebs Cycle or Citric Acid Cycle
a. Acetyl CoA + 4C molecule  6C citrate (citric acid) molecule Acetyl CoA released and recycled c. Enzymes break down acetyl group  CO2 + 4C molecule d. chemical energy captured in NADH, FADH2, ATP CO2 becomes a waste product 2 pyruvate generates (mitochondrial matrix reactions)  2 ATP, 8 NADH, 2 FADH2 & 6 CO2 Formation of acetyl CoA NADH NAD FAD FADH2 CO2 coenzyme A coenzyme A Krebs cycle acetyl CoA NAD NADH ADP ATP

10 Krebs Cycle or Citric Acid Cycle - Krebs Song

11 2 - ETC series of electron transporting molecules embedded in inner mitochondrial membrane (matrix) 1 H2O per 2 e- ADP ATP – ETC Video Donate e- & H+ P - ETC Song NADH FADH2 NAD FAD ATP synthase (inner membrane) ETC Energy either 1-lost as heat 2-pumps in H+ (intermembrane space) 11

12 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 . ht - Tyler Hamilton (Armstrong teammate)

13 ATP synthase
3 - Chemiosmosis Chemiosmosis: process by which energy is used to generate a concentration of H+ to generate ATP 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

14 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

15 STEPS INPUT OUTPUT NET GAIN Glycolysis 1 glucose 2 ATP 2 NAD 2 pyruvate 4 ATP 2 NADH Pyruvate Prep Step 2 NAD+ 2 acetyl groups 2 CO2 Krebs Cycle 2 acetyl 2CoA 6 NAD+ 2 FAD 2 CoA 6 NADH 2 FADH2 4CO2 4 CO2 ETC 8-10 NADH (1/2 O2) 8-10 NAD+ 6H2O 32 ATP TOTALS Glucose (+ O2) 6 CO2 36 ATP - CR Review – Crash Course in ATP and Respiration

16 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 – Why Can You Get Fat by Eating Sugar?

17 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

18 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, sour cream, cheese – Fermentation Video

19 Figure 8-8 Glycolysis followed by lactic acid fermentation
2 NAD 2 NADH 2 NADH 2 NAD (glycolysis) (fermentation) 1 glucose 2 pyruvate 2 lactate 2 ADP 2 ATP 19

20 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 acid fermentation in their leg muscle cells for their final burst of speed. – Lactic Acid and Fatigue

21 Alcoholic Fermentation?
many microorganisms like yeast engage in alcoholic fermentation under anaerobic conditions generates alcohol and CO2 from pyruvate like in lactic acid fermentation, NAD+ must be regenerated to allow glycolysis to continue Making ginerale 2 NAD 2 NADH 2 NADH 2 NAD (glycolysis) (fermentation) 1 glucose 2 pyruvate 2 ethanol 2 CO2 2 ADP 2 ATP

22 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.

23 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.

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