1. Chemical Reactions & Enzymes

2. Chemical Reactions Process that changes one set of chemicals into another set Reactants - things that go into reaction Products - things that come out of reaction

3. Chemical Reactions cont’d Always involve breaking bonds and forming new ones Example in our body – Carbon dioxide combines with water in the bloodstream to form carbonic acid so the carbon dioxide can be taken to the lungs

4. Energy in Reactions Energy Changes – Spontaneous reactions release energy – Other reactions must have energy added because they absorb energy – Energy is released as heat or light Activation energy – Amount of energy to start a reaction

5. Enzymes Catalyst - substance that speeds up rate of reaction Enzyme - are proteins that act as biological catalysts – Enzymes are very specific, each can catalyze only one reaction – The enzyme name contains the name of the reaction it acts on

6. Why are enzymes important to living things? CO 2 produced by cells is carried to your lungs through bloodstream and is then eliminated as you exhale. CO 2 is not very soluble in water. The bloodstream cannot dissolve enough CO 2 to carry it away from tissues were it for a chemical rxn. CO 2 reacts w/ H 2 O to produce a highly soluble carbonic acid H 2 CO 3. Left by itself, this rxn is so slow that CO 2 will build up in the body faster than the bloodstream could remove it. Your bloodstream contains an enzyme carbonic anhydrase that speeds up the rxn.

7. Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Reaction pathway with enzyme Reactants Products