Food molecules in grass are taken in by cow. Food molecules are in the grass 1

Food is mostly water and large organic molecules LIPIDS (FAT) STARCH CELLULOSE (FIBER) GLUCOSE (SUGAR) 2 CARBOHYDRATES: PROTEINS

Digestion occurs in stomach and small intestines Large food molecules break into small molecules in intestines 3 Note: digestive cells produce molecules (enzymes) that can break large organic molecules up into small organic molecules.

During digestion, large organic molecules are broken down into small organic molecules LARGE = Polymer 4 SMALL = Monomers STARCH GLUCOSE (SUGAR)

These large organic molecules cannot enter the cells LIPIDS (FAT) PROTEINS Why do animals digest, or break down, these molecules into smaller molecules the cells can use to do work?

Animals don’t digest all the food that they eat 6 Our digestive systems cannot break down some large organic molecules (such as fiber). These molecules leave our bodies as feces.

Breakdown Protein Molecules (Digestion) Let’s focus on what happens to PROTEIN in food. (Put the other food molecules to the side for now.) Digest PROTEIN molecules by cutting the protein into individual amino acids. Notice that after you cut the protein apart there are bonds without atoms. Cut up water molecules to tape an –H and –OH to every amino acid. 7 Chemical change

ProductsReactants Protein polymer (+ water) 8 What happens to carbon atoms and chemical energy in digestion? Amino acid monomers

Chemical change ProductsReactants Protein polymer (+ water) 9 What happens to carbon atoms and chemical energy in digestion? Amino acid monomers Carbon atoms stay in organic molecules with high-energy bonds

Breakdown of Starch Molecules (Digestion) Digest STARCH molecules by cutting the starch into individual glucose monomers. Notice that after you cut the starch apart there are bonds without atoms. Cut up water molecules to tape an –H and –OH to every glucose. 10 Chemical change

Products Glucose monomers Reactants Starch polymer (+ water) 11 What happens to carbon atoms and chemical energy in digestion?

Chemical change Products Glucose monomers Reactants Starch polymer (+ water) What happens to carbon atoms and chemical energy in digestion? 12 Carbon atoms stay in organic molecules with high-energy bonds

Breakdown of Fat Molecules (Digestion) Digest FAT molecules by breaking the fat into individual fatty acid and glycerol monomers. Notice that after you cut the fat apart there are bonds without atoms. Cut up water molecules to tape an –H and –OH to each fatty acid and glycerol. 13 Chemical change

Products Fatty acids + glycerol Reactants Fat (+ water) 14 What happens to carbon atoms and chemical energy in digestion?

Chemical change Products Fatty acids + glycerol Reactants Fat (+ water) 15 What happens to carbon atoms and chemical energy in digestion? Carbon atoms stay in organic molecules with high-energy bonds

Chemical change ProductsReactants Large organic molecules (+ water) 16 What happens to carbon atoms and chemical energy in digestion? Small organic molecules

Chemical change ProductsReactants Large organic molecules (+ water) 17 What happens to carbon atoms and chemical energy in digestion? Small organic molecules Carbon atoms stay in organic molecules with high-energy bonds

Small molecules move through circulatory system Circulation: Small molecules move from intestines to blood, and the heart pumps blood and small molecules to all parts of the body. 18

Where do the small molecules go? glucose glycerol amino acid fatty acid 19

Connecting Questions about Processes at Different Scales: Biosynthesis 20 ScaleQuestions Macroscopic ScaleHow do cows grow? Microscopic Scale How do cows’ cells use small organic molecules to grow? Atomic-Molecular Scale How do cells make their large organic molecules?

FoodDigestion Materials for growth: Biosynthesis Energy: Cellular respiration How do cows’ cells use food to grow? 21

Remember what’s in cow muscles PROTEIN FAT 22

What happens during biosynthesis? Chemical change Small organic molecules go into cells, but don’t come out. What happens inside the cells?

Build Cow Muscles (Biosynthesis) Build PROTEIN molecules by taping 4 amino acid monomers together. Notice you will need to remove an –H and –OH from each amino acid. Tape these back together to make water. 24 Chemical change

Products Protein polymer (+ water) Reactants 25 What happens to carbon atoms and chemical energy in biosynthesis? Amino acid monomers

Chemical change Products Protein polymer (+ water) Reactants 26 What happens to carbon atoms and chemical energy in biosynthesis? Amino acid monomers Carbon atoms stay in organic molecules with high-energy bonds

Build Cow Muscles (Biosynthesis) Build FAT molecules by taping 3 fatty acid monomers to 1 glycerol molecule. Notice you will need to remove an –H and –OH from each fatty acid and glycerol. Tape these back together to make water. 27 Chemical change

Products Fat (+ water) Reactants 28 What happens to carbon atoms and chemical energy in biosynthesis? Fatty acids + glycerol

Chemical change Products Fat (+ water) Reactants 29 What happens to carbon atoms and chemical energy in biosynthesis? Fatty acids + glycerol Carbon atoms stay in organic molecules with high-energy bonds

Large molecules are built here Biosynthesis is the process of small organic molecules becoming large organic molecules in individual cells. 30

Matter entering and leaving animals Materials in grass (entering cow) Materials in a cow Materials leave a cow by breathing, urination, feces, and perspiration. feces H2OH2O Protein Fat H2OH2O CO 2 minerals H2OH2O Carbohydrates minerals Fat Protein 31 From lungs H2OH2O Carbohydrates minerals Protein

FoodDigestion Materials for growth: Biosynthesis Energy: Cellular respiration How do cows’ cells use food to grow? 32

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? 33

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 34

Pick up handout and tape into journal: 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% (H 2 O) 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. 36

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. 39