1. ENZYMES

2. What’s an Enzyme?
Enzymes are proteins.
Enzymes are catalysts.
Catalysts speed up chemical reactions
End in –ase (Ex: sucrase, catalase)
Without an enzyme!
With an enzyme!

3. WARNING Superman had Kryptonite Mrs. Head had Organic Chemistry
Enzymes have
Acids (pH)
Cold Temperatures
Extreme Hot Temps
slow down the
enzyme and the
chem. reaction

4. Chemical Reactions
Reactants → (yield) Products
Ex: Fe + O2 → rust

5. Why do we need Enzymes?
Speed up rate of chemical reaction by lowering the activation energy (energy needed to start chemical reaction)
Without enzyme
Activation energy
without enzyme
Activation
Energy with enzyme
Reactants
With enzyme
Products

6. How do ENZYMES work? The enzyme attaches to reactants
The reactants that bind to the enzyme are known as the substrates.
The part of the enzyme where the substrate attaches to the enzyme is called the active site.
The shape of the active site only fits the shape of the substrate, like a lock fits a key. Only the correct substrate binds to the enzyme.

7. Lock-and-Key Mechanism- Enzymes can only bind to certain substrates
Reactants/
Substrates
Enzyme
Lock-and-Key Mechanism- Enzymes can only bind to certain substrates

8. How do you speed up enzymes?
Add more of the enzyme.
Warm up the enzyme! Don’t warm it too much or something may happen

9. Once the enzyme and substrate are together, the enzyme holds the substrate so the reaction can occur. Once the reaction is over, the enzyme unlocks the product and the enzyme can start a new reaction with an identical substrate.
Enzymes are not permanently changed or used up in reactions

10. A change in the pH of the enzyme can cause a change in the shape of the active site, therefore changing the activity of the enzyme.

11. Effect of Enzymes Reaction pathway without enzyme Activation energy
Reactants
Activation
energy
with enzyme
Reaction pathway
with enzyme
Products
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12. Figure 2-19 Chemical Reactions
Section 2-4
Energy-Absorbing Reaction
Energy-Releasing Reaction
Products
Activation
energy
Activation energy
Reactants
Reactants
Products
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