1. Biochemistry Chemistry of Life

2.  Matter – anything that has mass and takes of space  Mass – the amount of matter in a substance – measured in grams  Volume – amount of space a substance takes up – measured in milliliters  Element – Pure substances that cannot be broken down into simpler matter.  Important elements in living organisms: Hydrogen, Carbon, Oxygen and Nitrogen make up 96% of ALL living things.

3. ATOM  Simplest particle of an element – that still maintains the properties of that element.  Made of Protons (+ charge) Neutrons (neutral) Electrons (- charge)

4. Periodic Table

5.  Atomic # = # protons  Atomic # = # electrons  Atomic Mass – Atomic # = # neutrons  Electrons are arranged in shells. 2 electrons will fit in the first shell. 8 in the second and 18 in the third. Try drawing the atomic structure for the following elements: carbon, nitrogen, oxygen, hydrogen, sodium and chlorine.

6. Bonding  All atoms want 8 electrons in their outer shell. So they react to by creating bonds to form compounds.  Compounds are pure substances made of two or more atoms.  It is only the electrons in the outer shell that cause reactions and create bonds.  Look at your drawings of sodium and chlorine. How many electrons are in the outer shell for each of these?

7. Ionic Bonds  When electrons are given away.  Show example of Sodium and chlorine.  It is the difference in charges after electrons are exchanged that creates this bond.

8. Covalent Bonds  When electrons are shared.  Show example of carbon and hydrogen.  Polar covalent bond is when the electrons are not shared equally. One atom pulls harder on the electron than the other atom. Example Water.  Non polar – atoms share electrons equally. Ex. O 2

9. Chemical Reaction  A reaction that creates new bonds between atoms or breaks them apart. Reactants  Products H 2 + O 2  H 2 O  The bonds between the atoms contain energy – we get our energy from breaking those bonds – and we store energy by making those bonds. In living systems those bonds are primarily covalent.

10. Energy  All living systems need energy to do work. Where does all energy originate from?  reactions that release energy – exergonic  reactions that require energy – endergonic.  Most reactions whether exergonic or endergonic – they require start up energy and this is called activation energy.  For example, the food that our bodies break down gives us energy but some energy is required to start the reaction.

11. Catalyst  Catalysts reduce the amount of activation energy required and therefore speed up a reaction.  Enzymes are catalysts in living systems.  Without enzymes to lower the activation energy to break down our food, it would have to be heated MUCH higher than body temperature.  Ex. Lactase is an enzyme that breaks down lactose which is the sugar in milk.

12. Solutions  Solution is a mixture of a solute and solvent.  Solute is the solid or gas that is dissolved in the solvent.  Solvent is the liquid that the solute is dissolved in.  Ex. Plasma has many solutes dissolved in water.  Concentration is the measurement of the amount of solute dissolved in a fixed amount of liquid.

13. Acids and Bases  When solutions are made, many solutes will dissociate in the solvent (which is usually water).  Dissociate means to break apart.  Water dissociates a little bit.

14. pH  pH – is a logarithmic measurement of the amount of H+ present in a solution.  Pure water has an equal amount of H+ and OH- so its pH is 7  Acid is a solution where the amount of H+ is greater than OH-. Acids are less than 7 on the pH scale. Example: HCl  H+ + Cl-  Base is a solution where the amount of OH- is greater than the H+. Bases are more than 7 on the pH scale. Example: NaOH  Na + OH-

16.  Due to the logarithmic scale, a pH of 3 is 10 times more acidic than 4.  How many more times acidic is a pH of 3 than a pH of 5?  Why can we drink acidic beverages?  Our bodies contain buffers that can neutralize acids or bases. For example there are buffers in our blood which keep the blood pH at 7.5 which is critical for enzyme function.