1. LESSON 5 HOW ARE FOOD MOLECULES BUILT UP AND STORED?

2. ACTIVITY 5.1 We need food for growth during childhood. Do you think that an adult who is keeping a steady weight is also using food for building materials? Why? What do we know about proteins? What foods are rich in proteins? From the reading in the last activity, what happens to proteins in food in the stomach? In the last lesson, you constructed glucose molecules. Now construct amino acid molecules in much the same way.

3. Activity Sheet 5.1, which contains a research paper from 1939. Read the paper stopping after each section and write down questions. Answer the questions in your notebook. After methods section: We will look at the following: A leucine molecule, an amino acid, and an isotope. http://www.biotopics.co.uk/jsmol/leucine.html What is an amino acid? http://www.twigcarolina.com/films/glossary/isotope-4496/

4. NOTES TO TAKE The unmarked amino acid might be one of the ones already in the body. It is made from atoms, as they are usually found in nature. The model amino acid marked with tape might be one of the ones fed to the mice. This amino acid is made up of hydrogen and nitrogen atoms that are heavier than those usually found in nature. Scientists can tell the difference between these two amino acids because of the different mass of the atoms.

5. REVIEWING THE ACTIVITY How could it be that the amino acids were found in the proteins? (Is this a chemical reaction? How do you know? What are the reactants and products of this chemical reaction?

9. Comparing the two Reactions

10. Organisms use building materials from food they eat for growth (gaining weight and getting taller) and repair (like mending broken bones or replacing old skin cells). Both growing and repairing require new food molecules because organisms need material to make new cells to build up new structures in the body. Some food molecules that organisms eat are excreted as waste. The majority of food molecules that are eaten by an organism are found in the body of that organism because they are transported to the cells and used as the building materials for new cells and new structures inside cells. Summing it UP

11. LESSON 5.2 HOW ARE FOOD MOLECULES BUILT UP AND STORED

12. BRAINSTORM 1 If food has the capacity to provide our bodies with energy and we use energy all the time, why do we not need to eat all the time? You did not eat while exercising in Lesson 1 and you are not eating now while listening to me. How do you have energy to do these things when you are not eating? Where do people get energy when they sleep or when they are fasting (voluntarily not eating for long periods of time)?

13. BRAINSTORM When does your body use the food it eats to provide energy? Immediately, later, or both? Give evidence for your response. When does your body use food for energy immediately? When does your body store food to use for energy later

14. MAKE A CLAIM An example claim may be “My body stores the food molecules I eat if I do not use them right away. My cells can use these food molecules later for building materials or energy.”

15. SUPER SIZE ME Clips will give us data about the ability of the human body to store food molecules. The filmmaker ate McDonald‘s meals exclusively for 30 days. We will collect data from the two clips. Show the first clip of Super Size Me, which is segment 00:05:40 to 00:011:37. Show the second clip of Super Size Me, which is segment 01:29:39 to 1:30:25

16. AS WE ARE WATCHING PLEASE ANSWER THE FOLLOWING? What evidence does the movie give you about the ability of the body to store food? Does this data support your claim? Why did he gain weight? When do humans store food for later use?

17. AS WE ARE WATCHING…THINK Does all weight gain suggest that the body is storing food for later use? What about weight gain in children? When is weight gain storage and when is it growing? Plants can do the same thing by storing food molecules in their roots (like potatoes or carrots).

18. Draw a T-chart on the board and label the columns: (1) Food molecules eaten and (2) Molecules used to store food. What are the three types of food molecules animals eat? What evidence do you have? (Carbohydrates, fats, and proteins are the three types. Food labels from burning marshmallows, potato chips, oil, and tortilla chips are the evidence.) Write the names of the food molecules down on a board under “Food molecules eaten.” Based on the movie Super Size Me, what food molecules does your body use to store food? What evidence do you have? (Students might respond that the movie gave them evidence that the body stores fat that can later be used to provide energy to cells.) Write these food molecules on the board/overhead under “Molecules used to store food.” See the following chart.

20. How do you think the food molecules that you eat are stored? If you eat more carbohydrates, how does your body store them for a long time? Proteins? Fats? What is your evidence? (Students often think that carbohydrates can be stored as carbohydrates for a long time and that they cannot change into fats. Some students might reply that if you eat a lot of carbohydrates, you might gain weight, so carbohydrates can turn into fats.) Draw arrows between the food molecules eaten and the form that students think they can be stored as. Accept all answers at this point. Are the types of carbohydrate molecules you eat different from the type you store in your body? Does this mean a chemical reaction occurred? Why? Why do you think carbohydrates can/cannot be stored as fats? Does this mean a chemical reaction occurred? Why?

21. MAKING A CLAIM Guide students in writing a claim about what happens to food molecules so that they can be stored in the body for a long time. Record this claim on the board. An example claim might be “The molecules that I eat go through chemical reactions to become fat so that they can be stored in my body.”

22. Super Size Me, which is segment 1:13:00 to 1:17:30. What did the man drink? What kind of food molecules did the drink contain? (The man said that he drank about two gallons of soda pop a day. This drink contains carbohydrates.) What kind of food molecules is he storing in his body? (fat) If the man drank many carbohydrates found in soda pop, but his body stored fat, what happened to those carbohydrate molecules? (Carbohydrate molecules must go through a chemical reaction to be stored as fat.)

23. do you think that carbohydrate subunits could go through a chemical reaction to make fat subunits? Why? What would have happen to the carbohydrate subunits? (The carbohydrate subunits and fat subunits have the same atoms. If they underwent a chemical reaction where the atoms were rearranged, carbohydrate subunits could make fat molecules.)

24. Animals cannot store very much in the form of carbohydrates. Instead, their bodies turn excess carbohydrates and proteins into fats to be stored in fat tissues. This happens through a chemical reaction. This is not the only chemical reaction that happens to food molecules. The following are also chemical reactions. Generally, proteins are used as building materials, not storage. When you are growing, much more of the food you eat is used as building materials. However, the body can only use so much protein, and the rest can be converted to fat and stored. Fat molecules might also be changed into other fat molecules before they are stored. (You may need to remind students that there are many different kinds of fat molecules, not just the one type on PI: Food Molecules.

26. Discuss how the movie provided students with evidence that all three types of food molecules can go through chemical reactions to be stored as fat. Why is each of these processes for storage a chemical reaction? (The arrangement of atoms that makes up the molecules in the food we eat and the molecules used for storage differ. The properties of these molecules are also different. For example, the glucose in honey tastes sweet and is soluble in water, and these properties are not shared by fat.) Based on this activity, why could someone who eats very little fat in his or her diet still be obese? (Someone who eats more carbohydrates or proteins than they need for energy immediately would convert them into fat.) If you want to be a healthy weight, do you think it is more important to avoid fatty foods or to eat fewer Calories? Why? (Students might say that based on this activity it would be more important to eat fewer Calories if you want to be a healthy weight because you could eat too many carbohydrates and store them as fat.) How do you think what you learned in this activity about storage in animals compares to storage in plants? (Students might respond that plants store food as starch, protein, and oil. Rice contains starch molecules, nuts contain protein molecules, and seeds contain oil [fat molecules]. From previous units, students might respond that plants produce carbohydrates [glucose]. Therefore, the glucose will have to go through a chemical reaction to be stored as starch, protein, and oil.)