1. ENZYMES
Biological catalysts

2. Formation of life required catalysts
Metabolism is based on chemical reactions
Without catalysts, reactions occur too slowly to sustain life
Activation energy is the energy needed to start reactions

3. Catalysts
Lower the amount of activation energy needed to start a reaction
This speeds up reaction rates
Enzymes are proteins that act as biological catalysts

5. How do enzymes work??
Enzymes, like all proteins, have a definite 3-D shape
This 3-D shape fits the reactants, called substrates, like a lock and key
The place where substrates bind to the enzyme is called the activation site

6. How do enzymes work, cont.
Without enzymes, reactants would need to collide with enough force to break old bonds and form new ones
Enzymes provide a place where reactants are brought together
This lowers activation energy

7. Enzymes can be reused

8. Regulation of enzymes Cells can turn enzymes on or off
Enzymes work best at certain pH and temp.
If pH or temp. is not correct the enzyme will change shape or denature