1. Learning Targets “I Can...” -Define “enzyme.” -Define “substrate.” -Define “activation energy” and identify it on a reaction rate graph. -Describe the shape of enzymes compared to their substrates. -Define a “catalyst.” -Explain how enzymes are catalysts. -Explain what happens when the shape of an enzyme changes.

2. TIME (SECONDS) TOOTHPICKS METABOLIZED

4. Enzymes

5. All reactions in our bodies are possible because of enzymes 1. For most chemical reactions to begin, energy must be added. This energy is called the activation energy.activation 2. Enzymes lower the activation energy so that the reaction can occur easier Enzymes physically bring molecules closer together so they can find each other Enzymes are also known as catalysts because they speed up reactions A single organism may have thousands of enzymes, each one made for a particular reaction

6. Enzymes are proteins 1. Enzymes have specific structure, which allows them to depend on a physical fit between the enzyme and the substrate ( the molecule being broken down)

7. Enzymes are proteins 2. Substrates and enzymes fit together like a lock and keylock and key

8. Enzymes are proteins 3. Once the substrate is bound, the enzyme changes shape around the substrate to weaken chemical bonds

9. Enzymes are proteins 4. The enzyme releases the products once the reaction is completereleases the products

10. Enzymes are proteins 5. The enzyme is never changed in the process

11. Enzymes are proteins 6. If the enzyme shape is changed (i.e. denatured), the reaction cannot occur denatured

12. Can we speed up chemical reactions?speed reactions 1. Increase the number of substrate 2. Increase the number of enzyme 3. Increase the temperature 4. Decrease the size of the system 5. Yes, but reactions reach a point where they cannot get any faster, the enzyme becomes saturated

13. References http://www.wellesley.edu/Biology/Concept s/Html/enzymes.html