1. Chemistry of Life
AP Biology
Chapters 2 & 3

2. Biology <3’s Chemistry
Luciferin (Firefly)
Chemical involved in making fireflies glow
Pyrethrin (Chrysthanthemum)
Natural insecticide; acts as a contact poisons which quickly penetrate the nerve system of the insect.
Batrachotoxin (Golden Dart Frog)
Potent neurotoxin released when a frog feels threatened; 2 grains of salt’s worth would kill a 150 lb person

3. Matter & Mass
Matter is anything that has mass and takes up space

4. Atoms Smallest unit of matter Proton: positive Neutron: neutral
Electron: negative

5. Biological Importance of Atoms
Electrons:
hold potential energy
valence e-

6. Elements A collection of atoms substances
25 elements essential to life

7. CHNOPS C: building block H: provide energy N: amino acids
O: cellular respiration
P: DNA & energy
S: protein structure
 25 elements of life

8. Compound
Two or more elements combined in a fixed ratio

9. Chemical bonds Covalent: sharing electrons
Polar (H2O)
Nonpolar (Lipids, Oils)
Ionic: transferring electrons
NaCl
Hydrogen: weak
involve H
Van der Waals: weakest
give proteins 3D shape

10. Isotopes
Atoms that have the correct number of protons, but a different number of neutrons

11. Water
Chapter 3

12. Biological Importance of Water
Life evolved in water
All cells contain water
Biological reactions occur in water

13. Polar Covalent Bond - + H2O doesn’t share e- evenly
Oxygen atom is electronegative
Hydrogen atoms are slightly positive + -

14. Hydrogen Bonding
Occurs when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom
This bonding type allows water to have unique properties vital for living things

15. 1. Cohesion Water molecules stick together (H-bonding) Important for:
Surface tension
Capillary action

16. 2. Moderation of Temperature
Water has a high specific heat
a lot of energy is required to change its temperature.
Coastal climate
Evaporative cooling

17. 3. Good solvent Water dissolves other polar molecules
Salt, glucose, and enzymes
Water does not dissolve nonpolar molecules
Lipids
“like dissolves like”

18. 4. Floating ice insulates water
Less dense as solid than liquid

19. Water and pH
Occasionally, hydrogen will shift from one water molecule to another
The result is a hydronium ion (+) and a hydroxide ion (-)
Disassociation

20. Acids, Bases and pH Acids donate H+ ions to solutions
Bases donate OH- ions to solutions
Acids: pH 0-6
Bases: pH 8-14

21. Buffers
Substances that either accept or donate H+ ions in solution to try and minimize changes in pH of solution
Essential in living systems