1. Chemical Reactions and Enzymes
Bio- Chapter 2 section 4
Chemical Reactions and Enzymes
What are they?
How do they work?
Use your Cornell Notes

2. Chemical Reactions
Chemical reaction = process that changes one set of chemicals into another Beginning chemicals = reactants Ending chemicals = products Reactants  Products CO2 + H2O  H2CO3 Chemical reactions always rearrange chemical bonds

3. Energy in Reactions
Chemical reactions that release energy can happen spontaneously (no help needed) (exothermic) Chemical reactions that absorb energy will not occur without “activation energy” (endothermic) Activation energy – energy required to start a reaction Only needed at the start

4. Activation Energy

5. Enzymes
Catalyst = a substance that speeds up the rate of a chemical reaction Catalysts work by lowering the activation energy required for the reaction Enzymes = proteins that act as catalysts Enzymes speed up chemical reactions in cells Enzymes are very specific

6. Enzymes lower activation energy

7. Enzyme Action
Enzymes provide a site where reactants can be brought together to react Reactants at an enzyme site = substrates The site on the enzyme = active site Combination of enzyme and substrates = enzyme-substrate complex The shape of the active site is specific to a substrate

8. The active site is shape specific for a certain substrate
enzyme action

9. Some specific enzymes
Breaks down Starch in mouth and small intestine Breaks down protein in stomach Breaks down lipids in small intestine Breaks down milk sugar (lactose)
Amylase
Peptin
Lipase
Lactase