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General, Organic, & Biological Chemistry
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General, Organic, & Biological Chemistry
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Unformatted text preview: CHAPTER 9 Cellular Respiration and Fermentation Connect to the Big Idea Use the micrograph of the mitochondria to help students start thinking about the concepts of cellular respiration and fermentation. First, activate prior knowledge by asking them if they know what mitochondria are and what their function is. (cellular organelles that convert the chemical energy stored in food into chemical compounds that cells can use) Cellular Basis of Life Q: How do organisms obtain energy? Now ask students what links the cereal they had for breakfast with the mitochondria in the micrograph. (energy) Point out that food, like this morning’s cereal, contains molecules that the mitochondria can use to make energy available to cells. Then, ask why cells need energy. (to carry out cell activities) Ask students to anticipate the answer to the question, How do organisms obtain energy? Have students read over the Chapter Mystery and predict how sperm whales can stay active for so long on only one breath. To make their predictions, suggest students think about how cells obtain and release the energy whales need to dive. Use their predictions to help them start connecting the Chapter Mystery to the Big Idea of the Cellular Basis of Life. Have students preview the chapter vocabulary terms using the Flash Cards. Chapter 9 NATIONAL SCIENCE EDUCATION STANDARDS • Flash Cards 248 UNIFYING CONCEPTS AND PROCESSES I, III, V 0001_Bio10_se_Ch09_CO.indd 1 CONTENT B.3, C.1.a, C.1.b, C.5.a, C.5.b, C.5.c, C.5.d, F.1, G.1 INQUIRY A.1.b, A.1.c, A.1.f, A.2.a, A.2.d Understanding by Design A cell is the basic unit of life; the processes that occur at the cellular level provide the energy and basic structure organisms need to survive. Students explore this Enduring Understanding in Chapter 9 by examining the processes of cellular respiration and fermentation. As shown in the graphic organizer at the right, the Big Idea, Essential Question, and lesson-level Guiding Questions help frame their exploration. PERFORMANCE GOALS In Chapter 9, students will learn how cellular respiration and fermentation provide organisms with the energy they need to survive. Students will show this understanding by interpreting multiple, detailed figures. They will also practice their data analysis skills by collecting and interpreting data on the byproducts of cellular respiration. At the end of the chapter, students will transfer their knowledge by keeping an exercise journal and relating the entries to cellular respiration and fermentation. 248 Chapter 9 6/2/09 6:44:14 PM INSIDE: DIVING WITHOUT A BREATH • 9.1 Cellular Respiration: An Overview • 9.2 The Process of Cellular Respiration • 9.3 Fermentation Mitochondria (red) and smooth endoplasmic reticulum (yellow) in an ovarian cell (SEM 75,000×). Everyone is familiar with the sensation of being “out of breath.” Just a few minutes of vigorous exercise can have humans huffing and puffing for air. But what if you couldn’t get air? What if you were asked to hold your breath and exercise? Before too long, you’d pass out due to a lack of oxygen. This may seem like a silly thought experiment, but there are animals that exercise without breathing and without passing out all the time—whales. Unlike most animals that live their entire lives in water, whales still rely on oxygen obtained from air when they surface. Amazingly, sperm whales routinely stay underwater for 45 minutes or more when diving. Some scientists suspect that they can stay underwater for 90 minutes! How is that possible? Diving takes a lot of energy. How do whales stay active for so long on only one breath? As you read this chapter, look for clues. Then, solve the mystery. Never Stop Exploring Your World. Learning about whales and their extraordinary ability to hold their breaths is just the beginning. Take a video field trip with the ecogeeks of Untamed Science to see where this mystery leads. Extend your reach by using these and other digital assets offered at Biology.com. CHAPTER MYSTERY Discover how the processes of cellular respiration and fermentation can affect the behavior and function of an entire organism—in this case, how often whales need to breathe. UNTAMED SCIENCE Dive below the ocean surface to explore how marine mammals can survive on a single breath for as long as they do. ART IN MOTION An animated diagram highlights the relationship between photosynthesis and cellular respiration. INTERACTIVE ART In this short animation, students watch how glucose is broken down and energy is transferred during the process of cellular respiration. • Untamed Science Video ART REVIEW • Chapter Mystery Cellular Respiration and Fermentation 249 Students explore the details of electron transport and ATP synthesis. TUTOR TUBE 0001_Bio10_se_Ch09_CO.indd 249 Chapter 9 Big Idea: Cellular Basis of Life Chapter 9 EQ: How do organisms obtain energy? 6/9/09 1:36:31 PM 9.1 GQ: Why do most organisms undergo the process of cellular respiration? This short, online tutorial provides extra help on the electron transport chain and ATP production. DATA ANALYSIS Students analyze data to learn more about lactic acid and exercise. 9.2 GQ: How do cells release energy from food in the presence of oxygen? 9.3 GQ: How do cells release energy from food without oxygen? Cellular Respiration and Fermentation 249 CHAPTER 9 What’s Online LESSON 9.1 Cellular Respiration: An Overview Getting Started Objectives 9.1.1 Explain where organisms get the energy they need for life processes. 9.1.2 Define cellular respiration. Key Questions 9.1.3 Compare photosynthesis and cellular respiration. Where do organisms get energy? What is cellular respiration? Student Resources Study Workbooks A and B, 9.1 Worksheets Spanish Study Workbook, 9.1 Worksheets Lab Manual B, 9.1 Data Analysis Worksheet What is the relationship between photosynthesis and cellular respiration? Vocabulary calorie • cellular respiration • aerobic • anaerobic Taking Notes Lesson Overview • Lesson Notes • Activity: Art in Motion • Assessment: SelfTest, Lesson Assessment For corresponding lesson in the Foundation Edition, see pages 212–215. Activate Prior Knowledge Write the term cellular respiration on the board. Then, make a T-Chart below it. Label one column Facts and the other Questions. Have each student come up to the board and write either a fact they know or a question they have about cellular respiration. Discuss the T-Chart as a class. Answer any questions that students will need to know before reading the lesson. Preview Visuals Before you read, study Figure 9–2 on page 252. Make a list of questions that you have about the diagram. As you read, write down the answers to the questions. BUILD Vocabulary PREFIXES The prefix macromeans “large” or “elongated.” Macromolecules are made up of many smaller molecular subunits. Carbohydrates, proteins, and lipids are important macromolecules found in living things. Study Wkbks A/B, Appendix S30, T-Chart. Transparencies, GO15. THINK ABOUT IT When you are hungry, how do you feel? If you are like most people, you might feel sluggish, a little dizzy, and—above all—weak. Weakness is a feeling triggered by a lack of energy. You feel weak when you are hungry because food serves as a source of energy. Weakness is your body’s way of telling you that your energy supplies are low. But how does food get converted into a usable form of energy? Car engines have to burn gasoline in order to release its energy. Do our bodies burn food the way a car burns gasoline, or is there something more to it? Chemical Energy and Food Where do organisms get energy? Food provides living things with the chemical building blocks they need to grow and reproduce. Recall that some organisms, such as plants, are autotrophs, meaning that they make their own food through photosynthesis. Other organisms are heterotrophs, meaning that they rely on other organisms for food. For all organisms, food molecules contain chemical energy that is released when their chemical bonds are broken. Organisms get the energy they need from food. How much energy is actually present in food? Quite a lot, although it varies with the type of food. Energy stored in food is expressed in units of calories. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. The Calorie (capital C) that is used on food labels is a kilocalorie, or 1000 calories. Cells can use all sorts of molecules for food, including fats, proteins, and carbohydrates. The energy stored in each of these macromolecules varies because their chemical structures, and therefore their energy-storing bonds, differ. For example, 1 gram of the sugar glucose releases 3811 calories of heat energy when it is burned. By contrast, 1 gram of the triglyceride fats found in beef releases 8893 calories of heat energy when its bonds are broken. In general, carbohydrates and proteins contain approximately 4000 calories (4 Calories) of energy per gram, while fats contain approximately 9000 calories (9 Calories) per gram. Cells, of course, don’t simply burn food and release energy as heat. Instead, they break down food molecules gradually, capturing a little bit of chemical energy at key steps. This enables cells to use the energy stored in the chemical bonds of foods like glucose to produce compounds such as ATP that directly power the activities of the cell. NATIONAL SCIENCE EDUCATION STANDARDS Lesson 9.1 250 • Lesson Overview • Lesson Notes UNIFYING CONCEPTS AND PROCESSES I, V 0001_Bio10_se_Ch09_S1.indd 1 CONTENT B.3, C.1.a, C.1.b, C.5.a, C.5.c, C.5.d INQUIRY A.1.c, A.2.a, A.2.d Teach for Understanding ENDURING UNDERSTANDING A cell is the basic unit of life; the processes that occur at the cellular level provide the energy and basic structure organisms need to survive. GUIDING QUESTION Why do most organisms undergo the process of cellular respiration? EVIDENCE OF UNDERSTANDING At the end of the lesson, have students complete this assessment to show they understand the importance of cellular respiration for life on Earth. Have students make a case for cellular respiration. Ask them to write a short persuasive argument that explains why cellular respiration is an important process on an individual organism level as well as on a global scale. 250 Chapter 9 • Lesson 1 6/2/09 6:46:28 PM You Are What You Eat Food Organisms get energy from the food they eat, but the energy contained in foods varies greatly. Most foods contain a combination of proteins, carbohydrates, and fats. One gram of protein or a carbohydrate such as glucose contains roughly 4 Calories. One gram of fat, however, contains about 9 Calories. The accompanying table shows the approximate composition of one serving of some common foods. 1. Interpret Data Per serving, which of the foods included in the table has the most protein? Which has the most carbohydrates? Which has the most fat? Protein (g) Carbohydrate (g) Fat (g) Apple, 1 medium 0 22 0 Bacon, 2 slices 5 0 6 Chocolate, 1 bar 3 23 13 9 12 0 2% milk, 1 cup 8 12 5 Potato chips, 15 chips 2 14 10 11 3 1 Eggs, 2 whole Skinless roasted turkey, 3 slices Lead a Discussion Make sure students understand the overall chemical summary for cellular respiration. Reinforce that the bolded reactions shown are simplifications, or summations, of many sub-reactions. Have students verify that the reaction shown is balanced by counting the molecules of each element on the right and left sides of the reaction. 2. Calculate Approximately how many more Calories are there in 2 slices of bacon than there are in 3 slices of roasted turkey? Why is there a difference? DIFFERENTIATED INSTRUCTION 3. Calculate Walking at a moderate pace consumes around 300 Calories per hour. At that rate, how many minutes would you have to walk to burn the Calories in one chocolate bar? (Hint: Start by calculating the number of Calories consumed per minute by walking.) Overview of Cellular Respiration What is cellular respiration? If oxygen is available, organisms can obtain energy from food by a Cellular respiration is the process called cellular respiration. process that releases energy from food in the presence of oxygen. Although cellular respiration involves dozens of separate reactions, an overall chemical summary of the process is remarkably simple: In Words: Oxygen + Glucose L1 Struggling Students Write the word form of the cellular respiration summary on the board. Then, read it aloud, pointing to each word and reaction symbol as you read. For example, you might say, “oxygen and glucose are converted into carbon dioxide and water and energy.” As you say oxygen, point to the word; as you say and, point to the plus sign. Then, write the symbol form of the summary below it. Draw lines from each chemical formula to its corresponding name in the word form of the summary. ELL In Symbols: 6O2 + C6H12O6 LESSON 9.1 Teach Composition of Some Common Foods 6CO2 + 6H2O + Energy Focus on ELL: Build Background BEGINNING AND INTERMEDIATE SPEAKERS Carbon dioxide + Water + Energy As you can see, cellular respiration requires oxygen and a food molecule such as glucose, and it gives off carbon dioxide, water, and energy. Do not be misled, however, by the simplicity of this equation. If cellular respiration took place in just one step, all of the energy from glucose would be released at once, and most of it would be lost in the form of light and heat. Clearly, a living cell has to control that energy. It can’t simply start a fire—the cell has to release the explosive chemical energy in food molecules a little bit at a time. The cell needs to find a way to trap those little bits of energy by using them to make ATP. FIGURE 9 –1 A Controlled Release Cellular respiration involves a series of controlled reactions that slowly release the energy stored in food. If the energy were to be released too suddenly, most of it would be lost in the forms of light and heat—just as it is when a marshmallow catches fire. In Your Notebook Do plants undergo cellular respiration? What Distribute copies of a BKWL Chart to your students. Then, show students a short animation, video, or several drawings of the process of cellular respiration. Have them take notes on the visuals in the build background column. Write the words obtain, release, extract, respiration, and energy on the board. Have them copy the words and define each in the build background column. Then, have students fill out the K and W columns of the chart. As students read the lesson, have them fill in the L column. organelle(s) do they have that helps you determine the answer? Cellular Respiration and Fermentation 251 0001_Bio10_se_Ch09_S1.indd 2 PURPOSE Students will examine and interpret data to find how the energy content in foods varies. PLANNING Have a few of the foods listed in the table on hand, and display them for students before they do the activity. Ask students to predict which of the foods contain the most Calories, and have them explain their reasoning. Study Wkbks A/B, Appendix S27, BKWL Chart. Transparencies, GO12. 6/2/09 6:46:33 PM ANSWERS 1. Eggs have the most protein; chocolate has the most carbohydrates; chocolate has the most fat. 2. There are approximately 9 more Calories in 2 slices of bacon than in 3 slices of roast turkey. The primary difference is that the bacon contains so much more fat than the turkey. 3. a little over 44 minutes Answers IN YOUR NOTEBOOK Yes; they contain mitochondria. Cellular Respiration and Fermentation 251 LESSON 9.1 Glucose Teach Glycolysis continued Energy Use Visuals Use Figure 9–2 to talk about the overall process of cellular respiration. Start by helping students make the connection between this visual and the chemical summary equations from the previous page. Point out where and how glucose and oxygen are used during the process and that water, carbon dioxide, and energy are released. Make sure students understand that cellular respiration can be divided into three basic stages. Tell them that they will learn more detailed information about each of these stages in later lessons. DIFFERENTIATED INSTRUCTION L1 Struggling Students Have students read the section, Stages of Cellular Respiration, in the text and look carefully at Figure 9–2. As a class, discuss the first pictured stage, glycolysis. Then, have students write a one-sentence summary of the discussion. For example, students might write, “During glycolysis, glucose is broken down into pyruvic acid and energy is released.” Then, discuss and summarize each of the next two stages. To help students answer the question, remind them that whales need to surface to breathe air. Make the connection between aerobic pathways and the whale’s breathing. Ask them to speculate on how long the breath might last and how the whale might obtain energy once that air runs out. Students can go online to Biology.com to gather their evidence. Krebs Cycle Energy CO2 Electron Transport Energy O2 H 2O FIGURE 9 –2 The Stages of Cellular Respiration There are three stages to cellular respiration: glycolysis, the Krebs cycle, and the electron transport chain. Interpret Visuals Which stage(s) of cellular respiration occur in the mitochondrion? If whales remain underwater for 45 minutes or more, do you think they rely primarily on aerobic or anaerobic pathways? Answers FIGURE 9–2 the Krebs cycle and the electron transport chain IN YOUR NOTEBOOK Flowcharts should accurately show the connections between glycolysis, the Krebs cycle, and the electron transport chain. 252 Chapter 9 • Lesson 1 Oxygen and Energy Oxygen is required at the very end of the electron transport chain. Any time a cell’s demand for energy increases, its use of oxygen increases, too. As you know, the word respiration is often used as a synonym for breathing. This is why we have used the term cellular respiration to refer to energy-releasing pathways within the cell. The double meaning of respiration points out a crucial connection between cells and organisms: Most of the energy-releasing pathways within cells require oxygen, and that is the reason we need to breathe, to respire. Pathways of cellular respiration that require oxygen are said to be aerobic (“in air”). The Krebs cycle and electron transport chain are both aerobic processes. Even though the Krebs cycle does not directly require oxygen, it is classified as an aerobic process because it cannot run without the oxygen-requiring electron transport chain. Glycolysis, however, does not directly require oxygen, nor does it rely on an oxygen-requiring process to run. Glycolysis is therefore said to be anaerobic (“without air”). Even though glycolysis is anaerobic, it is considered part of cellular respiration because its final products are key reactants for the aerobic stages. Recall that mitochondria are structures in the cell that convert chemical energy stored in food to usable energy for the cell. Glycolysis actually occurs in the cytoplasm of a cell, but the Krebs cycle and electron transport chain, which generate the majority of ATP during cellular respiration, take place inside the mitochondria. If oxygen is not present, another anaerobic pathway, known as fermentation, makes it possible for the cell to keep glycolysis running, generating ATP to power cellular activity. You will learn more about fermentation later in this chapter. In Your Notebook Make a flowchart that shows the different steps of cellular respiration. Address Misconceptions Cellular Respiration v. Respiration Some of your students may have difficulty distinguishing between the concepts of cellular respiration and respiration as breathing. Have students read the first paragraph of the Oxygen and Energy section, research the connection between the two processes, and make a poster for the classroom wall that graphically shows the relationship. Stages of Cellular Respiration Cellular respiration captures the energy from food in three main stages—glycolysis, the Krebs cycle, and the electron transport chain. Alt...
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