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Chapter 9 Cell Respiration

Chapter 9 Cell Respiration. How much energy is in food?. One gram of glucose “burned” (oxidized) in presence of oxygen = 3811 calories of heat energy A calorie is the amount if energy needed to raise the temperature of one gram of water one degree Celsius.

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Chapter 9 Cell Respiration

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  1. Chapter 9Cell Respiration

  2. How much energy is in food? • One gram of glucose “burned” (oxidized) in presence of oxygen = 3811 calories of heat energy • A calorie is the amount if energy needed to raise the temperature of one gram of water one degree Celsius. • Kilocalorie on food labels (1 Calorie = 1000 calories) • When cells “burn” glucose, they release the energy contained within its chemical bonds.

  3. Oxygen or not? • Anaerobic: “not in air” Do not require oxygen • Glycolysis and fermentation • Aerobic pathways in cell respiration need oxygen to release energy from food. • Krebs cycle and ETC

  4. Overview of Cell Respiration Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. 6O2 + C6H12O6 6CO2 + 6H2O + Energy oxygen + glucose  carbon dioxide + water + energy Respiration Overview (3:50)

  5. The MIGHTY Mitochondrion Intermembranespace (H+ ions) Outer membrane Inner membrane (ETC) Matrix (Krebs) You might want to draw this!

  6. Glycolysis 4 ADP 2 ATP 2 ADP 4 ATP 2NAD+ 2 Pyruvic acid 2 Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid (pyruvate) Energy input of 2 ATPs; 4 ATPs produced; net gain of 2 ATPs.

  7. Glycolysis • Two high-energy electrons and H+ picked up by NAD+to make NADH • Energy in NADH carried to ETC • No oxygen needed and high speed are the advantages. • It’s a form of ATP production in O2-deprived cells (muscle) • and red blood cells (no mitochondria) 4 ADP 2 ATP 2 ADP 4 ATP 2NAD+ 2 2 Pyruvic acid

  8. Fermentation If there is no oxygen present, cell will go through fermentation Cells convert NADH to NAD+ by passing high energy electrons back to pyruvate, allowing glycolysis to continue producing a steady supply of ATP.

  9. Alcoholic Fermentation C6H12O6 + zymase 2C2H5OH + 2CO2 • Forms ethyl alcohol and CO2 as wastes. • Occurs mainly in yeast and a few other microorganisms • Causes bread dough to rise • When yeast in dough run out of oxygen, they begin to ferment, giving off bubbles of CO2. • Small amount of alcohol evaporates.

  10. Lactic Acid Fermentation • Regenerates NAD+ so glycolysis can continue. • Produced during vigorous exercise in muscles • Rapid production of ATP • Lactic acid is a waste product • Buildup of lactic acid in muscles causes a painful, burning sensation • Broken down into CO2 and H2O by liver

  11. Lactic Acid Fermentation • Cheese, yogurt, sour cream, pickles, and sauerkraut are produced using lactic acid fermentation.

  12. Review The first step of cellular respiration is… a. ETC b. Glycolysis c. Krebs cycle d. Fermentation

  13. Review Where does glycolysis occur? What occurs if there no oxygen present after glycolysis? a. The electrons from NADH will go to the ETC. b. The electrons from NADH will go to the Krebs cycle. c. ATP production will stop. d. NAD+ will be regenerated in fermentation.

  14. Review What are the two types of fermentation? This type of fermentation occurs in muscle cells: ________________

  15. Glycolysis 4 ADP 2 ATP 2 ADP 4 ATP 2NAD+ 2 Pyruvic acid 2 Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid (pyruvate) Energy input of 2 ATP

  16. Krebs Cycle During the Krebs cycle, pyruvate is broken down into CO2 in a series of energy-extracting reactions. Occurs in the matrix of mitochondrion. First described by Hans Krebs. aka: The Citric Acid Cycle

  17. Krebs Cycle Begins when pyruvate enters. One carbon from pyruvate becomes a part of CO2 and is released from the cell. At the same time, 2 electrons are combined with 1 H+ ion changing NAD+ into NADH. Next, coenzyme A joins the remaining 2 carbon molecules from pyruvate to form acetyl-CoA. Acetyl-CoA adds its two- carbon acetyl group to a 4-carbon compound (oxyloacetate) producing citric acid (citrate).

  18. Krebs Cycle Citrate is broken down into a 5-carbon compound (alpha-ketoglutarate) and more CO2 is released. Again, 2 electrons and 1 H+ ion convert NAD+ to NADH. Then, another carbon atom leaves in CO2 as a waste product, leaving a 4-carbon compound (malic acid/malate).

  19. Krebs Cycle Following that, 4 electrons and 2 H+ ions are removed changing 2 molecules of NAD+ into NADH. Also, ADP is converted into the energy molecule ATP. Finally, FAD is converted into FADH2 and malic acid moves on to start the cycle again. Krebs Review (1:55)

  20. Where do the products of the Krebs Cycle go? CO2 released into the air ATP used for cell activities NADH and FADH2 used to generate large amounts of ATP in the ETC.

  21. Review Where does the Krebs cycle take place? Number of ATPs generated by Krebs? Two electron carriers generated by Krebs? Waste product of Krebs?

  22. Electron Transport Chain ADP The ETC uses high-energy electrons from the Krebs cycle to convert 32 ADPs to 32 ATPs. Series of carrier proteins located in inner membrane of mitochondria.

  23. High-energy electrons from NADH and FADH2 are passed from one carrier to the next. • At the end, an enzyme combines these electrons with H+ions and oxygen to form water. • Oxygen serves as the final electron acceptor of the ETC. ADP

  24. Electron Transport Chain ADP Each time 2 electrons travel down the ETC, their energy is used to pump H+ ions across the membrane from the matrix of the mitochondria. H+ ions build up in the intermembrane space, making it positively charged and the outside negatively charged.

  25. Electron Transport Chain ETC Review (2:02) ADP This imbalance of charge between the matrix and the intermembrane space causes H+ ions to move through ATP synthase. ATP synthase turns when this happens, converting ADP to ATP. Average of 3 ATPs for every pair of electrons

  26. Review Number of ATPs produced in ETC? Waste product of ETC? Purpose of energetic electrons? Location of ETC in eukaryotes? Prokaryotes? What enables ATP synthase to produce ATP?

  27. So What’s the Point?? The overall goals of the four pathways are: a. Glycolysis: to convert glucose into pyruvate for fermentation or Krebs b. Fermentation: to produce NAD+ to keep glycolysis going c. Krebs: to produce FADH2 and NADH for the ETC d. ETC: to produce large amounts of ATP for the cell

  28. How much energy does a single molecule of glucose provide? Glycolysis = 2 ATP Krebs Cycle = 2 ATP ETC = 32 ATP TOTAL = 36 ATP 18 times more ATP produced with oxygen Respiration represents about 38 percent of total energy of glucose. Remaining 62 percent released as heat

  29. What happens when you need a burst of energy? Your body only contains enough ATP for a few seconds of intense activity. When you participate in vigorous exercise, after a few seconds your body will begin to produce ATP by lactic acid fermentation. This type of ATP production will last about 90 seconds.

  30. What happens if you need energy for longer than 90 seconds? • Cellular respiration is the only way to generate a continuing supply of ATP. • Releases energy slower than fermentation. • Which means athletes need to train and pace themselves. • Body stores energy in muscle and other tissues in the form of the carb glycogen, which can supply energy for 15-20 mins. • After that, body breaks down stored molecules, like fat for energy. • This is why running, swimming, etc are so good for weight control.

  31. Comparing Photosynthesis and Respiration • Energy flow takes place in opposite directions • Photosynthesis deposits energy; respiration withdraws energy • Cell respiration occurs in all eukaryotes and nearly all prokaryotes. • Photosynthesis occurs only in plants, algae, and some bacteria. • What happens to O2 and CO2 in plant cell?

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