1. 2-4 Chemical Reactions and Enzymes p50
Q: What happens to chemical bonds during chemical reactions? A: Chemical reactions involve changes in the chemical bonds that join atoms in compounds.

2. Reactants-what goes in. Products-what comes out. 2H + 0
Chemical Reactions
Reactants-what goes in.
Products-what comes out.
2H + 0
H2 O
Reactant Product

3. Energy in Reactions
Q: How do energy changes affect whether a chemical reaction will occur? A: Chemical reactions that release energy often occur on their own, or spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.

4. Energy Changes-
release (occur on own) and
absorb energy (energy
needed)
Activation Energy-
Energy needed to get
reaction started

5. Activation Energy Push cart. Takes a lot of energy to get started.
Take the break off cart & push. Takes less energy to get started because the activation energy was lowered by taking off the break. The enzyme acts like taking off the break.

6. Enzymes
Q: What role do enzymes play in living things and what affects their function? A: Enzymes speed up chemical reactions that take place in cells. Temperature, pH, and regulatory molecules can affect the activity of enzymes.

7. Enzymes-proteins that act as biological catalysts.
Catalyst-speeds up rate of reaction.

8. Enzyme Action Substrate-reactant of the enzyme-substrate complex
The Enzyme-Substrate Complex is like a Lock & Key.
The enzyme can be reused.
1.substrates come together 2
can be reused 4 3

10. Regulation of Enzyme Activity
Room temperature is best. Higher & lower slows down the reaction.
Change in pH slows down the reaction.
Both of these destroy the shape of the active site.