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Carbon: Transformations in Matter and Energy Environmental Literacy Project Michigan State University Animals Unit Activity 5.1: Tracing the Processes for Cows Growing: Digestion and Biosynthesis Unit Map You are here 2 Connecting Questions about Processes at Different Scales: Digestion Scale Unanswered Questions Macroscopic Scale How to cows get food to all of their cells? Microscopic Scale How do food molecules get into a cow’s blood? AtomicMolecular Scale How are molecules in food changed chemically so that cow cells can use them? 3 Food molecules are in the grass Place two nickels here: large food molecules (grass). 4 What happens to the food cows eat? Food Digestion Energy: Cellular respiration 5 Food is mostly water and large organic molecules CARBOHYDRATES: STARCH LIPIDS (FAT) GLUCOSE (SUGAR) PROTEINS CELLULOSE (FIBER) 6 These large organic molecules cannot enter the cells LIPIDS (FAT) PROTEINS How do animals digest, or break down, these molecules into smaller molecules the cells can use to do work? Digestion occurs in stomach and small intestines Put nickels here: Large food molecules break into small molecules in intestines Exchange one nickel for 5 pennies (small organic molecules) Note: digestive cells produce molecules (enzymes) that can break large organic molecules up into small organic molecules. 8 During digestion, large organic molecules are broken down into small organic molecules STARCH GLUCOSE (SUGAR) 9 Animals don’t digest all the food that they eat Our digestive systems cannot break down some large organic molecules (such as fiber). Have the remaining nickel leave the cow as feces These molecules leave our bodies as feces. 10 What happens to carbon atoms and chemical energy in digestion? Chemical change Large organic molecules (+ water) Reactants 11 Small organic molecules Products What happens to carbon atoms and chemical energy in digestion? Chemical change Large organic molecules (+ water) Reactants 12 Carbon atoms stay in organic molecules with high-energy bonds Small organic molecules Products Small molecules move from intestines to blood, and the heart pumps blood and small molecules to all parts of the body. Move Pennies: Small molecules move through circulatory system 13 Where do the small molecules go? glucose glycerol fatty acid amino acid 14 Connecting Questions about Processes at Different Scales: Biosynthesis Scale Unanswered Questions Macroscopic Scale How do cows grow? Microscopic Scale How do cows’ cells use small organic molecules to grow? AtomicMolecular Scale How do cells make their large organic molecules? 15 How do cows’ cells use food to grow? Materials for growth: Biosynthesis Food Digestion Energy: Cellular respiration 16 What happens during biosynthesis? Chemical change Small organic molecules go into cells, but don’t come out. What happens inside the cells? Biosynthesis is the process of small organic molecules becoming large organic molecules in individual cells. Place your pennies here: Large molecules are built here Exchange your 5 pennies (small organic molecules) for a nickel (large organic molecule) 18 During biosynthesis, small organic molecules are built into large organic molecules GLUCOSE (SUGAR) STARCH 19 What happens to carbon atoms and chemical energy in biosynthesis? Chemical change Small organic molecules Reactants 20 Large organic molecules (+ water) Products What happens to carbon atoms and chemical energy in biosynthesis? Chemical change Small organic molecules Reactants 21 Carbon atoms stay in organic molecules with Large organic molecules (+ water) high-energy bonds Products How do animal cells use glucose? • The diets of most animals—including mealworms, cows, and humans—include lots of carbohydrates (starch, fiber, sugar) • This means that lots of glucose travels to animal cells in the blood. • BUT animal cells don’t make starch or cellulose. • How do they use the glucose? 22 Animal cells use glucose in two ways 1. Animal cells can combine glucose molecules with oxygen to release chemical energy in cellular respiration. – This is how all cells get the energy they need for their functions. 2. Animal cells can make fat molecules from glucose molecules. – Glycerol and fatty acids are made of the same atoms—C, H, and O—as glucose molecules – Animals use fats to store chemical energy in C-C and C-H bonds 23 Where do the atoms in animals come from? Work with a partner to complete the first chart about atoms. Remembering Nutrition Labels Animal cells are made of: • Water: around 60% (H2O) • Large organic molecules: less than 40% – Fats: Made of CHO atoms – Proteins: Made of CHON atoms – (Some other large organic molecules such as DNA, made from CHONP) • Minerals: around 1% – Many kinds of atoms: sodium, calcium, magnesium, etc. 25 Where does the energy in animals come from? Work with a partner to complete the second chart about energy. Chemical Energy • Chemical energy is stored in C-C and C-H bonds. • Does water have chemical energy? • Does air have chemical energy? • Does food have chemical energy? Additional Metabolic Pathways There are many more small organic molecules and ways they can be changed other than the ones in this lesson. Look at the Metabolic Pathways poster to see some of them. 28