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9-1 Chemical Pathways Slide 1 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways 9-1 Chemical Pathways Food serves as a source of raw materials to build cells in the body and as a source of energy. Animal Plant Slide 2 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Chemical Energy and Food Chemical Energy and Food ●One gram of the sugar glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories (3.811 Cal) of heat energy. ●What would happen to a cell when that energy is released ● THE CELL WOULD BLOW UP!!!!!!!!!!!!!!!!!!!! ●Do you see a problem with this? (A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.) Slide 3 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Chemical Energy and Food ●Cells don't “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds AND…. ●Transfer that energy in to other energy rich molecules, like… ATP NADH and FADH2 (similar to NADPH) Slide 4 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways 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. Slide 5 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Overview of Cellular Respiration The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen + glucose → carbon dioxide + water + energy ●How is this equation similar to photosynthesis? ●What is the form of the energy? Is it light? • NO!!! It is ATP ●It turns out that each glucose can produce a total of about 38 ATP (36 net). Slide 6 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Overview of Cellular Respiration Each of the three stages of cellular respiration captures some of the chemical energy available in food molecules (glucose) and uses it to produce ATP. 1.Glycolysis 2.Kreb’s cycle 3.Electron transport chain Slide 7 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Overview of Cellular Respiration Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Glycolysis Cytoplasm Mitochondrion Slide 8 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Overview of Cellular Respiration Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria. Cell membrane Glycolysis Cytoplasm Mitochondrion Slide 9 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Glycolysis What happens during the process of glycolysis? Slide 10 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Glycolysis 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. • Glycolysis releases a small amount of energy. • glucose (6-C) becomes pyruvic acid (3-C) X2 • How many total carbon atoms are still present? »6 carbons still present Slide 11 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Glycolysis This gives the cell a net gain of 2 ATP molecules. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid Slide 12 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Glycolysis NADH Production One reaction of glycolysis removes 4 high-energy electrons, passing them to an electron carrier called NAD+. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2NAD+ 2 Pyruvic acid Slide 13 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Glycolysis Each NAD+ accepts a pair of high-energy electrons and becomes an NADH molecule—a high energy molecule. The NADH molecule holds the electrons until they can be transferred to other molecules. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2NAD+ 2 2 Pyruvic acid Slide 14 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Glycolysis Summarize what has been used and made… ATP? NADH? 2 ATP 2 ADP 4 ADP 2NAD+ 4 ATP 2 2 Pyruvic acid To the electron transport chain Copyright Pearson Prentice Hall Slide 15 of 39 9-1 Chemical Pathways Glycolysis The Advantages of Glycolysis The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. Glycolysis does not require oxygen. *Disadvantage: only 2 ATP and 2 NADH; not enough to “run” a multi-cellular organism Slide 16 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Fermentation Fermentation When oxygen is not present, glycolysis is followed by a different pathway. The combined process of this pathway and glycolysis is called fermentation. Two types of fermentation: 1.Alcoholic fermentation 2.Lactic acid fermentation Slide 17 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Fermentation The two main types of fermentation are lactic acid fermentation and alcoholic fermentation. Slide 18 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Fermentation The first part of fermentaition is glycolysis. Slide 19 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Fermentation The second part shows the conversion of pyruvic acid to lactic acid (or ethanol and CO2). NAD+ is regenerated for glycolysis to continue; get some ATP Slide 20 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways Fermentation: Ethanol formation +1 CO2 ethanol Slide 21 of 39 Copyright Pearson Prentice Hall 9-1 Click to Launch: Continue to: - or - Slide 22 of 39 Copyright Pearson Prentice Hall 9-1 The raw materials required for cellular respiration are a. carbon dioxide and oxygen. b. glucose and water. c. glucose and oxygen. d. carbon dioxide and water. Slide 23 of 39 Copyright Pearson Prentice Hall 9-1 Glycolysis occurs in the a. mitochondria. b. cytoplasm. c. nucleus. d. chloroplasts. Slide 24 of 39 Copyright Pearson Prentice Hall 9-1 The net gain of ATP molecules after glycolysis is a. 3 ATP molecules. b. 2 ATP molecules. c. 3 pyruvic acid molecules. d. 4 pyruvic acid molecules. Slide 25 of 39 Copyright Pearson Prentice Hall 9-1 Fermentation releases energy from food molecules in the absence of a. oxygen. b. glucose. c. NADH. d. alcohol. Slide 26 of 39 Copyright Pearson Prentice Hall 9-1 The first step in fermentation is always a. lactic acid production. b. the Krebs cycle. c. glycolysis. d. alcohol production. Slide 27 of 39 Copyright Pearson Prentice Hall END OF SECTION