1. Lesson 2.4: Chemical Reactions & Enzymes

2. Chemical Reactions:
A chemical reaction is a process that changes one set of chemicals into another by rearranging chemical bonds
The elements you start with are reactants
The elements you end with are products

3. Chemical Reactions:
Exothermic Reaction- chemical reactions that release energy into surroundings; usually occur spontaneously
Endothermic Reaction- chemical reactions that absorb energy from surroundings; usually require a source of energy

4. Chemical Reactions:
The energy that is needed to get a reaction started is called the activation energy
Activate = start

5. Chemical Reactions:
Some chemical reactions are too slow or have activation energies that are too high to make them practical for living tissue
Catalysts speed up reactions by lowering the activation energy

6. Enzymes: Enzymes are proteins that act as biological catalysts
Enzymes speed up chemical reactions in cells

7. Enzyme- Substrate Complex:
The reactants of enzyme-catalyzed reactions are known as substrates
Enzymes break down substrates into the products

8. Enzyme- Substrate Complex:
The substrates bind to a site on the enzyme called the active site
The fit is so precise that the active site and substrates are often compared to a lock and key

9. Enzyme Activity:
Temperature and pH can denature enzymes, preventing it from working
Presence of other molecules can also affect enzymatic activity

10. Enzyme Examples: