Chapter 9

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Chapter 9

  1. 1. Chapter 9Cellular Respiration
  2. 2. Chemical Energy• Living things get energy from the food they consume• Calorie – the amount of energy needed to raise the temperature of 1 gram of water 1 °C• 1 gram of glucose when burned in the presence of oxygen releases 3811 C
  3. 3. Cellular respiration• Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen (aerobic)• 6O2 + C6H12O6 → 6CO2 + 6H2O + energy• Oxygen + glucose → carbon dioxide + water + energy• Three main stages: – Glycolysis – Krebs Cycle – Electron transport
  4. 4. Glycolysis• The process in which one molecule of glucose is broken in half producing two molecules of pyruvic acid; a 3-carbon compound• 2 ATP molecules are used to get the reaction going and will produce 4 ATP molecules when the process is complete
  5. 5. Cont.• NAD+ (electron carrier) accepts 4 high energy electrons and becomes NADH• This process can produce thousands of ATP molecules in a few milliseconds• Does not require oxygen (anaerobic)• Energy is used up quickly
  6. 6. Fermentation• Production of ATP in the absence of oxygen (anaerobic)• Two types: Alcoholic fermentation and Lactic acid fermentation• Alcohol fermentation: NADH is converted back to NAD+ by passing high energy electrons back to pyruvic acid• Pyruvic acid + NADH → alcohol + CO2 and NAD+
  7. 7. Cont.• Lactic fermentation: NADH is converted back to NAD+ by passing high energy electrons back to pyruvic acid and producing lactic acid• Lactic acid is produced in muscle when the body cannot supply enough oxygen• Pyruvic acid + NADH → lactic acid + NAD+
  8. 8. Krebs Cycle• End of glycolysis, 90% of chemical energy in glucose is still unused, cell will use oxygen to extract the remaining energy• Krebs cycle begins when pyruvic acid produced by glycolysis enters the mitochondrion• Pyruvic acid is used to make carbon dioxide, ATP, NADH, and FADH2
  9. 9. Electron Transport Chain• Uses the high energy electrons from the Krebs cycle to convert ADP to ATP• In eukaryotes: inner membrane of the mitochondrion• In prokaryotes: in the cell membrane• H+ builds up in the intermembrane space making it positively charged…other side, is now negatively charged
  10. 10. • As H+ escape through membrane, the mitochondria contain proteins (ATP synthase) which rotates, the enzyme grabs the low energy ADP and attaches a phosphate forming high energy ATP• Process is repeated over and over
  11. 11. Energy for the body• Quick – gylcolysis or fermentation• Long term- cellular respiration
  12. 12. Summary• Cellular respiration has 3 stages: – Glycolysis – Krebs cycle• Electron transport chain

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