1. Involve chemical reactions
Releases more energy than is absorbed
Absorb more energy than is released
Involve chemical reactions
Excess energy released as heat or light
Endothermic reactions
Energy is absorbed and released
Exothermic reactions
Products have more bond energy than the reactants
Products have lower bond energy than the reactants
Involve changes in energy

2. KEY CONCEPT Enzymes are catalysts for chemical reactions in living things.

3. Enzymes are catalysts in living things.
Enzymes are needed for almost all processes.
Breaking down food and building proteins
Most enzymes are proteins.

4. Who would win this race?
Finish Line
Team #1
Team #2

5. Catalysts are substances that speed up chemical reactions.
decreases or lower activation energy
increases reaction rate

6. Without a catalyst
Activation energy

7. With a catalyst the reaction starts faster!!!!!!
Activation energy

8. Disruptions in homeostasis can prevent enzymes from functioning.
Changes in temperature and pH can break hydrogen bonds
An enzyme’s function depends on its structure

9. Substrates- specific reactants that enzymes act on active site
An enzyme’s structure allows only certain reactants to bind to the enzyme.
Substrates- specific reactants that enzymes act on
active site
substrates (reactants)
enzyme
Substrates bind to an enzyme at certain places called active sites.

10. The lock-and-key model helps illustrate how enzymes function.
substrates brought together
bonds in substrates weakened
Substrates bind to an enzyme at certain places called active sites.
The enzyme brings substrates together and weakens their bonds.
The catalyzed reaction forms a product that is released from the enzyme.

11. How does a catalyst affect the activation energy of a chemical reaction?

12. Answer
Decreases the activation energy needed to start a chemical reaction AND also increases the rate of the chemical reaction.