1. The Chemistry of Life
2.2 Properties of water

2. Bellwork – What role do enzymes play in living things and what affects their functions?

3. What happens to chemical bonds during chemical reactions?
Chemical reaction – process that changes one group of chemicals to another
Mass and energy are conserved
Can happen slowly or quickly
Reactants – elements or compounds that enter into a chemical reaction
Products – Elements or compounds produced by a chemical reaction
Chemical reactions involve changes in the chemical bonds that join atoms together in compounds

4. Energy in reactions
Energy is released or absorbed whenever a bond is formed or broken
Chemical reactions always involve changes in energy
Chemical reactions that release energy often occur independently
Chemical reactions that require energy will not occur without an energy source
Example of energy releasing reaction – hydrogen reacting with oxygen
Energy released as heat, light and sound
To generate H2 from H2O you need to put in a lot of energy

5. Sources of energy In order to stay alive organisms need energy
Every organism must have a source of energy to carry out chemical reactions
Energy is conserved in chemical reactions
Plants get energy from light
Animals get energy from food
Energy released during day to day processes

6. Activation energy
Reaction that release energy do not always occur spontaneously
How do you burn paper
You light it with a match…
Then the cellulose in paper releases both heat and light energy
Activation energy is the energy required to get a reaction started

7. Endothermic and Exothermic reactions

8. Catalysts
Some reactions have very high activation energies, or occur too slowly to be of any use
A catalyst speeds up the rate of a reaction
Lower a reactions activation energy
Catalysts are not used up during a reaction

9. Enzymes
What role do enzymes play in living things, and what affects their function?
Enzymes are proteins that acts as natures catalyst
They speed up chemical reactions that take place in cells
Like all catalysts they lower the activation energy

10. Example - carbonic anhydrase
Formula explains how carbon dioxide is removed from the body
In nature this is a very slow reaction
In the presence of carbonic anhydrase it occurs 10million times faster
Essentially Instantaneous!

11. Enzyme – substrate complex
Chemical reactions depend on reactants colliding
With enough energy to ensure that the reaction takes place
Existing bonds need to break, new bonds need to form
If insufficient bonds remain unchanged after collision
Enzymes provide a site where reactants can be bought together to react
Reduces required amount of energy for a reaction
Reactants in an enzyme catalyzed reaction are called a substrate
Substrates bind to active site of an enzyme
Complementary shapes
Like a lock and key

12. Regulation of enzyme activity
Enzymes can be affected by any variable that affects the rate of a reaction
Temperature pH
Regulatory molecules
Temperature is key
Most enzymes in human body work best at 37 °C.
Enzymes work best at specific pH conditions
When conditions aren’t ideal enzymes can become denatured
Enzymes can be switched off by chemical signals when they are not needed