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CHAPTER 9 - CELLULAR RESPIRATION

CHAPTER 9 - CELLULAR RESPIRATION. CELLULAR RESPIRATION. Process that releases energy by breaking down food molecules in the presence of oxygen 6 O 2 + C 6 H 12 O 6 --> 6 CO 2 + 6 H 2 0 oxygen + glucose --> carbon dioxide + water + energy. 3 Stages of Cellular Respiration. Glycolysis

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CHAPTER 9 - CELLULAR RESPIRATION

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  1. CHAPTER 9 - CELLULAR RESPIRATION

  2. CELLULAR RESPIRATION • Process that releases energy by breaking down food molecules in the presence of oxygen • 6 O2 + C6H12O6 --> 6 CO2 + 6 H20 • oxygen + glucose --> carbon dioxide + water + energy

  3. 3 Stages of Cellular Respiration • Glycolysis • Krebs Cycle • Electron Transport Chain • Each stage captures some of the chemical energy available in food molecules and uses it to produce ATP

  4. Energy Molecules of Cellular Respiration • In cellular respiration, several molecules are used as energy carriers. These molecules carry energy from one step of cellular • ADP + P = ATP • NAD + H = NADH • FAD+ + H2 = FADH2

  5. GLYCOLYSIS • Glycolysis– First step in releasing the energy of glucose. • A molecule of glucose is broken into two molecules of pyruvic acid (a 3-carbon compound). • takes place in the cytoplasm • does not require oxygen - anaerobic

  6. GLYCOLYSIS • Requires: 1 Glucose molecule (C6H12O6), 2 ATP • Produces: 2 ATP, 2 NADH and 2 pyruvic acid

  7. Second Stage: Fermentation or Krebs Cycle • Glycolysis can be followed by fermentation or the Krebs cycle depending if oxygen is present. • Fermentation will occur if no oxygen is present. • Krebs Cycle will occur if oxygen is present.

  8. Glycolysis Fermentation Krebs Cycle Anaerobic (no oxygen) Aerobic (oxygen)

  9. Without Oxygen - Fermentation • Anaerobic - without the presence of oxygen • Fermentation - releases energy from food molecules in the absence of oxygen • two types: Alcoholic and Lactic Acid Fermentation • Occurs in the cytoplasm

  10. Types of Fermentation • Alcoholic - causes bread to rise, used to make beer and wine • Lactic Acid - produced in muscles during rapid exercise when body can’t supply enough O2 • causes painful, burning sensation and muscle soreness

  11. With Oxygen - Kreb’s Cycle • Aerobic - in the presence of oxygen • Kreb’s Cycle also called Citric Acid Cycle • Kreb’s Cycle - 2nd stage of cellular respiration, in which pyruvic acid is broken down into CO2 in a series of energy-extracting reactions, creating energy molecules. • Occurs in the mitochondria

  12. Kreb’s Cycle • Requires: 1 Pyruvic Acid • Produces: CO2, NADH, FADH2, ATP

  13. Kreb’s Cycle • As a pyruvic acid molecule enters the mitochondria, a carbon is removed, forming CO2. • Carbons continue to be rearranged, releasing more CO2, while allowing the energy carriers to be charged. • This cycle will happen twice for every molecule of glucose broken down in glycolysis.

  14. Third Stage: Electron Transport Chain • The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP into ATP. • Occurs in the mitochondrial matrix.

  15. Electron Transport Chain (ETC) • Requires: NADH, FADH2, ADP • Produces: H2O, NAD, FAD, ATP

  16. Electron Transport Chain • The Krebs Cycle generates high-energy electrons that are passed to NADH and FADH2. • The high-energy electrons (H+) from NADH and FADH2 are used up and passed along the proteins in the ETC.

  17. Electron Transport Chain • Oxygen serves as the final electron acceptor forming a water molecule. • As H+ ions move through the ETC, ATP synthase spins adding ADP to P forming ATP.

  18. Cellular Respiration Totals • 1 molecule of glucose produces: • 2 ATP in glycolysis • 34 ATP in Kreb’s Cycle and Electron Transport Chain • water • CO2

  19. Types of Energy • Quick Energy - Muscles only contain enough ATP for a few seconds of intense activity. Then, muscle cells produce their ATP by lactic acid fermentation. • Long Term Energy - Cellular Respiration is the only way to generate a continuing supply of ATP • energy is released more slowly than fermentation, which is why athletes have to pace themselves • 15 to 20 min. of activity from carbohydrate stored in the body • after 20 min., energy comes from break down of fats

  20. Photosynthesis vs. Respiration • Photosynthesis and cellular respiration take place in opposite directions! Photosynthesis: Use light energy to build a sugar. carbon dioxide + water + light energy → sugars + oxygen Respiration: Break down sugar to release energy. oxygen + sugars → carbon dioxide + water + energy

  21. Photosynthesis vs. Respiration • Photosynthesis: • Use light energy to build a sugar. • Process that “deposits” or captures energy. • Removes carbon dioxide from the atmosphere. • Releases oxygen into the atmosphere.

  22. Photosynthesis vs. Respiration • Respiration: • Break down sugar to release energy. • Process that “withdraws” or releases energy. • Removes oxygen from the atmosphere. • Releases carbon dioxide into the atmosphere.

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