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Cellular Respiration

Chapter 9. Cellular Respiration. Cellular respiration- part 1 Cellular respiration – part 2 Cellular respiration – part 3. Introduction Videoes. Chemical pathways. The foods we, and other animals eat, provide the raw materials needed for cells to synthesize new molecules.

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Cellular Respiration

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  1. Chapter 9 Cellular Respiration

  2. Cellular respiration- part 1 Cellular respiration – part 2 Cellular respiration – part 3 Introduction Videoes

  3. Chemical pathways • The foods we, and other animals eat, provide the raw materials needed for cells to synthesize new molecules. • These molecules will serve as the building blocks needed for growth and development of new cells. • Foods also provide energy for the cells in living things.

  4. Chemical energy and foods • An essential roll of foods is to provide the living thing with the energy to carry out the daily activities of life. • Foods provide the chemical energy needed by the cells of living things.

  5. The energy in foods • The energy in foods is measured in calories. • A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

  6. Calories (Kcal) • The Calorie (capital “C”) that is used on food labels is a kilocalorie, or 1000 calories.

  7. Cellular respiration • Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presences of oxygen.

  8. Stages of cellular respiration • Glycolysis • Krebs cycle • Electron transport phosphorylation (occurs in electron transport chain)

  9. 6O2 + C6H12O6 -------6CO2+ H2O + energy Oxygen + glucose produces carbon + water + energy dioxide • Cellular respiration • Requires food and oxygen • Produces carbon dioxide and energy Cellular respiration equation

  10. Glycolysis Krebs cycle Electron transport chain Stages of cellular respiration

  11. glycolysis • Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound.

  12. glycolysis • Requires 2 molecules of ATP • Produces: • 4 ATP for a net gain of 2 ATP • NADH • Pyruvic acid • Takes place in the cytoplasm. • Very fast process that produces thousands of ATP in a few milliseconds. • Does not require oxygen. • Problem – the available NAD+ molecules become filled with ATP and the cell cannot keep glycolysis going.

  13. Process of producing ATP in the absence of oxygen. • cells convert NADH to NAD+ by passing high-energy electrons back to pyruvic acid. • Process is said to be anaerobic, “not in air.” • Two types of fermentation: • Alcohol fermentation • Lactic acid fermentation fermentation

  14. Alcohol fermentation • Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes. • Produces carbon dioxide as well as alcohol. • Alcoholic fermentation causes bread dough to rise.

  15. Lactic acid fermentation • the pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid. • This process regenerates NAD+ so that glycolysis can continue.

  16. Lactic acid fermentation • Vigorous exercise can cause the accumulation of lactic acid in large muscles, leading to muscle soreness.

  17. Lactic acid fermentation • Unicellular organisms also produce lactic acid as a waste product during fermentation. • Prokaryotes are used in the production of a wide variety of foods and beverages, such as cheese, yogurt, buttermilk, and sour cream.

  18. The Krebs cycle • In the presence of oxygen, pyruvic acid produced in glycolysis passes to the second stage of cellular respiration, the Krebs cycle. • Named after Hanes Krebs.

  19. Citric acid cycle • Pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. • Citric acid is the first compound formed in this series of reactions,

  20. The term cellular respiration refers to energy-releasing pathways within the cell Oxygen is required for the final steps of cellular respiration. Because the pathways of cellular respiration require oxygen, they are said to be aerobic (with oxygen). Takes place inside the mitochondria. Krebs cycle

  21. Krebs cycle • Begins when pyruvic acid produced by glycolysis enters the mitochondrion. • The other two carbon atoms from pyruvic acid are joined to a compound called coenzyme A to form acetyl-CoA. • Acetyl-CoA adds the 2-carbon acetyl group to a 4-carbon molecule, producing a 6-carbon molecule called citric acid.

  22. Krebs cycle • Citric acid (6-carbon molecule) is broken down into a 5-carbon compound. • A second carbon is removed forming a 4-carbon compound. • With each change carbon dioxide is released, and electrons are transferred to energy carriers (NAD+ and FAD).

  23. Krebs cycle • With each cycle a molecule similar to ADP is turned into ATP. • CO2 is removed from the body as the animal exhales. • The ATP produced directly in the Krebs cycle can be used for cellular activities.

  24. Krebs cycle • The 4-carbon molecule is ready to accept another 2-carbon acetyle group, starting the cycle over again. • The cell will use the high-energy electrons in NADH to generate large amounts of ATP in the electron transport chain.

  25. Electron transport chain • The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP into ATP. • The beauty of this system is the way in which it couples the movement of high-energy electrons with the production of ATP.

  26. etc • High-energy electrons from NADH and FADH2 are passed along the electron transport chain. • At the end of the electron transport chain is an enzyme that combines these electrons with hydrogen ions and oxygen to form water. • Oxygen serves as the final electron acceptor of the electron transport chain.

  27. etc • Every time 2 high-energy electrons transport down the electron transport chain, their energy is used to transport hydrogen ions (H+) across the membrane. • During electron transport, H+ ions build up in the intermembrane space, making it positively charged. • The other side of the membrane, from which those H+ ions have been taken, is now negatively charged

  28. etc • The inner membranes of the mitochondria contain protein spheres called ATP synthases. • As H+ ions escape through channels into these proteins, the ATP synthases spin. • Each time it rotates, the enzyme grabs a low-energy ADP and attaches a phosphate, forming high-energy ATP

  29. Total atp • The Krebs cycle and electron transport enable the cell to produce 34 more ATP molecules per glucose molecule, in addition to the 2 ATP molecules obtained from glycolysis. • Total ATP - 36

  30. Energy and exercise • Begin the race using ATP stored in the muscle cells. • After 10 sec. ATP produced by lactic acid fermentation. • After 90 sec. ATP is produce by cellular respiration, using O2. • Fuel source • 15 – 20 min. – CHO • Longer 20 min – fats

  31. Photosynthesis is the process that “deposits” energy. Cellular respiration is the process that “withdraws” energy. Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back. Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses that oxygen to release energy from food. The release of energy by cellular respiration takes place in all eukaryotes and some prokaryotes. Energy capture by photosynthesis, however, occurs only in plants, algae, and some bacteria. Photosynthesis vs. cellular respiration

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