1. Enzymes

2. Enzyme Demonstration
Starch is digested by the enzyme amylase found in saliva.
Amylase in saliva, starch in paper…so if I draw on paper with saliva, amylase can break down the starch.
What will happen when I stain with iodine?
Ask 4 0r 5 volunteers Take a sterile swab, insert it in your mouth to saturate it with saliva, use it to write a secret message on a piece of paper. Wait 5 minutes then spray with dilute starch.

3. Vocabulary 1. Enzyme: biological catalyst
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Vocabulary
1. Enzyme: biological catalyst
2. Substrate: substance that an enzyme works on
3. Active site: place on enzyme where substrate attaches to enzyme
4. Enzyme-substrate complex: molecule that forms when substrate is bound to enzyme
5. Product: substance formed as a result of enzyme action

4. Activation Energy Activation Energy needed without Enzyme
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Activation Energy
Activation Energy needed without Enzyme
Activation Energy needed with Enzyme
Available energy given off

5. Enzymes are 1. Proteins that catalyze chemical reactions.
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Enzymes are
1. Proteins that catalyze chemical reactions.
Catalyst –speeds up rate of chemical reactions
2. Catalysts for biological reactions.
Lower the energy required to make a reaction occur.
Lowers the activation energy
They don’t make any reactions happen that wouldn’t have happened anyway

6. Types of Enzymes 1. Food enzymes: break down polymers into monomers
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Types of Enzymes
1. Food enzymes: break down polymers into monomers
2. Metabolic enzymes: control chemical processes that occur in the body

7. Digestive Enzymes 1. Salivary amylase: digests carbohydrates
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1. Salivary amylase: digests carbohydrates
2. Pepsin: digests proteins
3. Lipase: digests lipids
Digestive enzymes break polymers down into monomers

8. Enzymes lower the amount of energy needed to start a reaction.
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Metabolic Pathways
Enzymes lower the amount of energy needed to start a reaction.
Enzyme A
Enzyme B
Substrate Bi-Product End Product
If Enzyme B is NOT present, can the product be made?
What is the purpose of Enzyme A ?

9. About Enzymes 1. Enzymes are proteins.
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About Enzymes
1. Enzymes are proteins.
2. Enzymes are specific; can only catalyze ONE chemical reaction.
3. Only a small amount of enzyme is produced
4. Enzymes DO NOT get used up; they are reused over and over again.
5. Enzymes can become saturated (more substrate that enzyme).
To increase the amount of product, you have to add more enzyme

10. Enzymes are not Changed in Reactions
At the end of the reaction, the enzyme (sucrase) is free to catalyze another reaction.

11. Enzymes are Affected By:
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Enzymes are Affected By:
1. Temperature: heat destroys enzymes
2. pH: destroys enzymes
3. Amount of substrate: can saturate enzymes
4. Inhibitors: keep the enzymes from doing its job

12. Type of Inhibitors 1. Competitive inhibitors: compete for active site
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Type of Inhibitors
1. Competitive inhibitors: compete for active site
Slows rate of product formation
2. Noncompetitive inhibitors: attaches to another site; changes shape of active site
Noncompetitive inhibitor changes shape of active site
Competitive inhibitor blocks active site

13. Review: What are enzymes? What do they do? What is a substrate?
What is an active site?
What is induced fit?
What is an enzyme substrate complex?
How does catalase fit the model?