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Name: Date: Per: Row: Ch 9: Cellular Respiration 9-1 Chemical Pathways A. Chemical Energy and Food 1. Food serves as a source of raw materials for the cells in the body and as a source of energy. 2. Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria. 3. One gram of the sugar glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories of heat energy. 4. Calorie- the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. 5. Cells don't “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds. 6. This process begins with a pathway called glycolysis. 7. Glycolysis releases a small amount of energy. B. 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. 1. The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6 H2O + Energy oxygen + glucose → carbon dioxide + water + Energy Big Idea/Question/Notes: Name: Date: Per: Row: 2. Each of the three stages of cellular respiration captures some of the chemical energy available in food molecules and uses it to produce ATP. Cellular Respiration Overview Use the words provided to label the diagram of cellular respiration on the lines provided. ~ ATP, electron transport chain, glycolysis, Krebs cycle, mitochondria 1. __________________________ 2. __________________________ 3. __________________________ 4. __________________________ 5. __________________________ Answer: 1. glycolysis; 2. ATP; 3. Krebs cycle; 4. mitochondria; 5. ETC Big Idea/Question/Notes: Name: Date: Per: Row: B. Glycolysis 1. Glycolysis takes place in the cytoplasm. 2. The Krebs cycle and electron transport take place in the mitochondria. 3. Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound. 4. ATP Production a. At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction. b. When glycolysis is complete, 4 ATP molecules have been produced. c. This gives the cell a net gain of 2 ATP molecules. 5. NADH Production a. One reaction of glycolysis removes 4 high-energy electrons, passing them to an electron carrier called NAD+. b. Each NAD+ accepts a pair of high-energy electrons and becomes an NADH molecule. c. The NADH molecule holds the electrons until they can be transferred to other molecules. 6. The Advantages of Glycolysis a. The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. b. Glycolysis does not require oxygen. Big Idea/Question/Notes: Name: Date: Per: Row: C. Fermentation 1. When oxygen is not present, fermentation follows glycolysis. 2. Fermentation releases energy from food molecules by producing ATP in the absence of oxygen. 3. During fermentation, cells convert NADH back into the electron carrier NAD+ that is needed for glycolysis. 4. This lets glycolysis continue to make a steady supply of ATP. 5. Fermentation does not require oxygen—it is an anaerobic process. 6. The two main types of fermentation are lactic acid fermentation and alcoholic fermentation. D. Alcoholic Fermentation 1. Yeasts and a few other microorganisms use alcoholic fermentation a. forming ethyl alcohol and carbon dioxide as wastes. 2. The equation for alcoholic fermentation after glycolysis is: pyruvic acid + NADH → alcohol + CO2 + NAD+ E. Lactic Acid Fermentation 1. Lactic acid fermentation occurs in muscles during rapid exercise 2. Lactic acid fermentation converts glucose into lactic acid. Big Idea/Question/Notes: Name: Date: Per: Row: 3. The equation for lactic acid fermentation after glycolysis is: pyruvic acid + NADH → lactic acid + NAD+ Glycolysis and Fermentation ~ Follow the prompts to identify the important parts of glycolysis and fermentation Color the carbon atoms blue Circle the place where ATP is formed Mark and X on the place where ATP is used Q: How many carbon atoms are in one molecule of glucose? A: 6 Q: What is the product of glycolysis? A: pyruvic acid Big Idea/Question/Notes: Name: Date: Per: Row: 9-2 The Krebs Cycle and Electron Transport A. Introduction 1. When oxygen is available, glycolysis is followed by the Krebs cycle and the electron transport chain. 2. The three pathways together make up the process called cellular respiration. 3. Because the pathways of cellular respiration require oxygen they are aerobic. B. The Krebs Cycle- Background 1. The Krebs cycle is the second stage of cellular respiration 2. In eukaryotes, the Krebs cycle takes place in the mitochondria 3. The Krebs cycle is also known as the citric acid cycle, because citric acid is one of the first products 4. During the Krebs cycle, pyruvic acid is broken down into carbon dioxide by a series of energy-extracting reactions C. The Krebs Cycle- How it works! 1. The Krebs cycle begins when pyruvic acid produced by glycolysis enters the mitochondrion. 2. One carbon molecule is removed, forming CO2, and electrons are removed, changing NAD+ to NADH. 3. Coenzyme A joins the 2-carbon molecule, forming acetyl-CoA. 4. Acetyl-CoA then adds the 2-carbon acetyl group to a 4carbon compound, forming citric acid. Big Idea/Question/Notes: Name: Date: Per: Row: 5. Citric acid is broken down into a 5-carbon compound, then into a 4-carbon compound. 6. Two more molecules of CO2 are released and electrons join NAD+ and FAD, forming NADH and FADH2 7. In addition, one molecule of ATP is generated. 8. The energy tally from 1 molecule of pyruvic acid is a. 4 NADH b. 1 FADH2 c. 1 ATP The Krebs Cycle ~ Follow the prompts to identify the important parts of the Krebs cycle Color the carbon atoms blue Circle the electron carriers in green Circle ATP in orange Q: What does the cell do with all those high-energy electrons in carriers like NADH? A: Big Idea/Question/Notes: Name: Date: Per: Row: D. Electron Transport How are high-energy electrons used by the electron transport chain? The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP into ATP. 1. Electron transport is the third stage of cellular respiration. 2. The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP to ATP. 3. In eukaryotes this process takes place in the inner membrane of the mitochondria 4. In this pathway, high-energy electrons move from one carrier protein to the next. 5. Their energy is used to move hydrogen ions across the membrane through a protein called ATP synthase 6. Each time ATP synthase spins, a phosphate group is added to an ADP molecule, producing an ATP molecule. Big Idea/Question/Notes: Name: Date: Per: Row: The Electron Transport ~ Label the diagram with the following terms: electron, hydrogen ion, and inner membrane Q: Where in the mitochond rion does the electron transport chain take place? A: Q: What happens to the high-energy electrons from the Krebs cycle? A: 7. In the absence of oxygen, all the energy that a cell can extract from 1 glucose molecule is 2 ATP molecules (the product of glycolysis) 8. In the presence of oxygen, the cell can extract many more ATP molecules! Big Idea/Question/Notes: Name: Date: Per: Row: a. The Krebs cycle and the electron transport chain enable the cell to produce 34 more ATP molecules per glucose molecule!!! **Complete the table using the words below. Some words may be used more than once. carbon dioxide energy release mitochondria water Photosynthesis Cellular Respiration Energy capture Function Chloroplasts Location Glucose & oxygen Reactants Oxygen & glucose Products Answers: Function- energy release Location- mitochondria Reactants- water and carbon dioxide Products- carbon dioxide and water E. Energy and Exercise 1. Human body cells normally contain small amounts of ATP produced during cellular respiration 2. When the body needs energy in a hurry, muscle cells produce ATP by lactic acid fermentation Big Idea/Question/Notes: Name: Date: Per: Row: 3. On a global level, photosynthesis and cellular respiration are also opposites a. Photosynthesis removes CO2 from the atmosphere and puts back O2 b. Cellular respiration removes O2 and puts back CO2 Big Idea/Question/Notes: