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Chapter 6

Chapter 6. Cellular Respiration. Do Now:. The overall photosynthesis equation is as follows: 6CO 2 + 6H 2 O + Energy  C 6 H 12 O 6 + 6O 2 What type of RXN is this? Why are the autotrophs creating sugar? How do heterotrophs use the sugar created by autotrophs?

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Chapter 6

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  1. Chapter 6 Cellular Respiration

  2. Do Now: • The overall photosynthesis equation is as follows: 6CO2 + 6H2O + Energy C6H12O6 + 6O2 • What type of RXN is this? • Why are the autotrophs creating sugar? • How do heterotrophs use the sugar created by autotrophs? • What do you think the equation for using sugar might look like? (try rewriting the photosynthesis equation backwards) • Think back to cell structures. What cell organelle do you think may have play a large role in utilizing sugar for energy?

  3. Food serves as a source of raw materials for the cells in the body and as a source of energy. Animal Cells Animal Mitochondrion Plant Plant Cells

  4. Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria. Intermembrane space Outer membrane Animal Cells Mitochondrion Inner membrane Plant Cells Matrix

  5. Chemical Energy and Food • Cells gradually release the energy from glucose and other organic compounds. • This process begins with a pathway called glycolysis. • Glycolysis releases a small amount of energy.

  6. Overview of Cellular Respiration • Overview of Cellular Respiration • If oxygen is present, glycolysis is followed by the Krebs cycle and the electron transport chain. • Glycolysis, the Krebscycle, and the electron transport chain make up a process called cellular respiration.

  7. Overview of Cellular Respiration • What is cellular respiration?

  8. Overview of Cellular Respiration Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvicacid Glucose Glycolysis Cytoplasm Mitochondrion

  9. Overview of Cellular Respiration • Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.

  10. Overview of Cellular Respiration • The equation for cellular respiration is: • 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy • oxygen + glucose → carbon dioxide + water + energy

  11. Overview of Cellular Respiration • Each of the three stages of cellular respiration captures some of the chemical energy available in food molecules and uses it to produce ATP.

  12. Overview of Cellular Respiration • Glycolysistakes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria. Glycolysis Cytoplasm Mitochondrion

  13. “Do Now 2” (11/12/10) • What is the difference between aerobic and anaerobic? • Explain the meaning of respiration in cellular respiration. • Write the equation (in words) for photosynthesis. • Write the equation (in words) for cellular respiration. • Compare and contrast the two.

  14. Glycolysis • What happens during the process of glycolysis?

  15. Glycolysis • Glycolysis (C6H12O6) • Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvate, or pyruvic acid, a 3-carbon compound.

  16. Glycolysis • ATP Production • At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction. 2 ATP 4 ADP 2 ADP 4 ATP Glucose-6-phosphate Glucose PGAL 2 Pyruvic acid

  17. Glycolysis • When glycolysis is complete, 4 ATP moleculeshave been produced via substrate-level phosphorylation. • Direct transfer of a phosphate group from a substrate of a rxn to another molecule. 4 ADP 2 ATP 2 ADP 4 ATP Glucose-6-phosphate Glucose PGAL 2 Pyruvic acid

  18. Glycolysis • This gives the cell a net gain of 2 ATP molecules. 4 ADP 2 ATP 2 ADP 4 ATP Glucose-6-phosphate Glucose PGAL 2 Pyruvic acid

  19. Glycolysis • NADH Production • One reaction of glycolysis removes 4 high-energy electrons, passing them to an electron carrier called NAD+. 4 ADP 2 ATP 2 ADP 4 ATP Glucose-6-phosphate Glucose PGAL 2 Pyruvic acid 2NAD+

  20. Glycolysis • Each NAD+ accepts a pair of high-energy electrons and becomes an NADH molecule. 4 ADP 2 ATP 2 ADP 4 ATP Glucose-6-phosphate Glucose PGAL 2 Pyruvic acid 2NAD+ 2

  21. Glycolysis • The NADH molecule holds the electrons until they can be transferred to other molecules. 4 ADP 4 ATP Glucose-6-phosphate 2NAD+ 2 Pyruvic acid 2 To the electrontransport chain

  22. Glycolysis • The Advantages of Glycolysis • The process of glycolysis is so fastthat cells can produce thousands of ATP molecules in a few milliseconds. • Glycolysis does notrequire oxygen.

  23. Fermentation • Fermentation: AnaerobicRespiration • When oxygen is not present, glycolysis is followed by a different pathway. • Fermentation releases energy from food molecules by producing ATP in the absence of oxygen. • Fermentation does not require oxygen—it is an anaerobic process.

  24. Fermentation • The two main types of fermentation are lactic acid fermentation and alcoholic fermentation.

  25. Alcoholic Fermentation • Cannot be done by animals. • Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes. • The equation for alcoholic fermentation after glycolysis is: pyruvic acid ethanol + • + NADH CO2 + NAD+

  26. Fermentation • Lactic Acid Fermentation • In many cells, pyruvate that accumulates as a result of glycolysis can be converted to lactic acid. • This type of fermentation is called lactic acid fermentation. It regenerates NAD+ so that glycolysis can continue.

  27. Fermentation • Lactic acid fermentation converts glucose into lactic acid.

  28. Fermentation • The first part of the equation is glycolysis.

  29. Fermentation • The second part shows the conversion of pyruvate to lactic acid.

  30. Fermentation • The equation for lactic acid fermentation after glycolysis is: • Pyruvate + NADH → lactic acid + NAD+

  31. Fermentation • Muscle cells are capable of this type of fermentation. • Build-up of lactic acid causes muscle soreness & fatigue. • Lactic acid is usually diffuses into blood stream and is sent to the liver where it is converted back to pyruvate.

  32. Review glycolysis, ATP, NADH, aerobic vs. anaerobic respiration, Alcoholic & Lactic Acid Fermentation • What happens to the pyruvic acid created in glycolysis when oxygen is present in a cell? DO NOW What cells in our body likely use lactic acid fermentation during exercise? Explain your answer.

  33. Review

  34. The raw materials required for cellular respiration are • carbon dioxide and oxygen. • glucose and water. • glucose and oxygen. • carbon dioxide and water.

  35. Glycolysis occurs in the • mitochondria. • cytoplasm. • nucleus. • chloroplasts.

  36. The net gain of ATP molecules after glycolysis is • 3 ATP molecules. • 2 ATP molecules. • 3 pyruvic acid molecules. • 4 pyruvic acid molecules.

  37. Fermentation releases energy from food molecules in the absence of • oxygen. • glucose. • NADH. • alcohol.

  38. The first step in fermentation is always • lactic acid production. • the Krebs cycle. • glycolysis. • alcohol production.

  39. What is the equation for cellular respiration? • The equation for cellular respiration is: • 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy • oxygen + glucose → carbon dioxide + water + energy

  40. How is NADH formed • NAD+ is reduced & gains a pair of high energy electrons.

  41. What is required to start glycolysis? What is your net product? • 2 ATP required • Net gain of: • 2 ATP • 2 NADH • 2 Pyruvic Acids

  42. The Krebs Cycle and Electron Transport • Oxygen is required for the final steps of cellular respiration. • Because the pathways of cellular respiration require oxygen, they are aerobic.

  43. The Krebs Cycle • The Krebs Cycle • In the presence of oxygen, pyruvic acid produced in glycolysis passes to the second stage of cellular respiration, the Krebs cycle.

  44. The Krebs Cycle • What happens during the Krebs cycle? • During the Krebs Cycle, more ATP forms, Carbon is lost as Carbon Dioxide, & coenzymes latch onto electrons & hydrogen stripped from intermediates of the reactions.

  45. The Krebs Cycle • During the Krebscycle, pyruvicacidis broken down into carbon dioxide in a series of energy-extracting reactions. • Occurs in the matrix: the innermost compartment of the mitochondria

  46. The Krebs Cycle • The Krebs cycle begins when pyruvic acid produced by glycolysis enters the mitochondrion.

  47. The Krebs Cycle • One carbon molecule is removed, forming CO2, and electrons are removed, changing NAD+ to NADH.

  48. The Krebs Cycle • Coenzyme A joins the 2-carbon molecule, forming acetyl-CoA.

  49. The Krebs Cycle • Carbon enters the Krebs Cycle when Acetyl-CoA then transfers the 2-carbon acetyl group to oxaloacetate, a 4-carbon compound, forming citrate. Citrate Oxaloacetate

  50. The Krebs Cycle • Citric acid is broken down into a 5-carbon compound, then into a 4-carbon compound.

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