1. How Do Food Molecules Provide Organisms With Building Materials?

2. Let’s go back to our first example… How does my mouth change carbohydrates? Can you describe what happens when you eat a piece of toast?

3. Toast is made of the carbohydrate starch. When I eat toast, it gets chewed up and mixed with saliva in my mouth. An enzyme in the saliva helps starch react with water to break down into carbohydrate subunits.

4. KEY IDEAS!! Food subunits can provide the body with energy. Breaking down large food molecules like starch into glucose does not provide the body with energy. The purpose of digestion is to make food molecules smaller so that they can get into the cells where they undergo reactions to provide the body with energy.

5. ReactantsProducts BREAKDOWN OF FOOD MOLECULES FOR CARBOHYDRATES: Long chains of carbohydrate subunits (i.e. starch) and water. FOR PROTEINS: Long chains of protein subunits and water. Carbohydrate subunits (glucose) Protein subunits (amino acids)

6. You have really grown a lot since you were a baby!!

7. Where does that difference in mass come from? Where did your body get the material to make you taller? THE FOOD YOU EAT!! FOOD PROVIDES BUILDING MATERIALS FOR CELLS!!

8. Were we able to find evidence to support the claim that food molecules are used as building materials in the body? Can the same chemical reaction happen in plants?

10. How does this chemical reaction compare to breaking down food molecules? REACTANTSPRODUCTS Build up of Food MoleculesFor CARBOHYDRATES – Carbohydrate subunits (glucose.) For PROTEINS – Protein subunits (amino acids.) Long chains of carbohydrate subunits and water (i.e. starch) Long chains of protein subunits and water.

11. Organisms use building materials from the food they eat for growth (gaining weight and getting taller) and repair (like mending broken bones or replacing old skin cells.)

12. 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 of cells.

13. BUT HOW DOES IT ALL HAPPEN???

14. CHEMICAL REACTIONS!!

15. CHEMICAL REACTION: Atoms rearrange to form a new substance!

16. Both plants and animals store food for later use when they have more food than they need for energy immediately. Both plants and animals can use these food molecules later when they do not have enough food to provide energy for various activities.

18. Where does all of this energy come from in the first place?