1. Chemical Reactions and Enzymes
2.4
Everything that happens in an organism is based on chemical reactions.

2. What is a chemical reaction?
Process that changes one set of chemicals into another.
Mass and energy are conserved during a reaction
Law of Conservation of Matter-atoms cannot be created or destroyed

3. Parts of a reaction CO2 + H2O ------------- H2CO3
Reactants=what “enters” the chemical reaction
Listed BEFORE the arrow
Products=what is produced in the reaction
Listed AFTER the arrow
CO2 + H2O  H2CO3

4. Energy in Reactions
Release of energy—often occur on their own (seen as heat, light, sound) exothermic
Absorption of energy---need a source of energy to occur endothermic
Activation Energy---energy needed to get a reaction started

5. 2.5 Enzymes
Catalyst=substance that speeds up the rate of a chemical reaction by decreasing activation energy
Enzyme=proteins that act as biological catalysts….they speed up the cell’s reaction
lowers activation energy
very specific: one enzyme works on one reaction

6. How Enzymes Work
Provide a place where substrates (the reactants) are brought together to react (active site)
The substrates and active site fit together like a key in a lock (called the enzyme- substrate complex)
Stay together until the reaction is complete, then products are released

8. Enzymes… Work best at certain pH levels Have an optimum temperature
Changing the best temperature or pH can cause the enzyme to be denatured- meaning the shape of the enzyme changes and it will no longer work.

9. Addition of the enzyme lowers the activation energy in the reaction

10. REMEMBER: enzymes are easiest to recognize by their names in a chemical equation. Generally they will end in -ASE!!