Notes: 2/16/09
Characteristics of Living Organisms
1. Cells
- (multicellular or unicellular- bacteria, amoeba)
2. Obtain nutrition
- autotrophs= make their own food
- heterotrophs= consume food from environment
3. Gas exchange with environment
4. Reproduce
5. Metabolism - All the chemical processes that go on to keep an organism alive
6. Homeostasis - constant internal environment (temperature, heartrate, Oxygen, food)
7. Capacity to evolve (change over time)
Ways Living Organisms can be Different:
1. Some organisms have cell walls, others have only a cell membrane.
2. Some cells have cell walls composed of cellulose (plants)
Some walls are composed of chitin (fungi)
Others of peptidoglycan (bacteria)
6 Kingdoms of Classification (How Living organisms are classified/organized):
1. Archaebacteria
- extremophiles
- thermophiles: hot springs
- "high-temp loving"
- methanophiles
- "methane-loving"
- cowguts
- acidophiles
- "acid-loving"
- halophiles
- "salt-loving"
- prokaryotes, chemoautotrophs
- (make food using chemicals from the environment)

Biology Notes 3/10/09
Structure of Cell Membrane:
(see notes for drawings)
- phospholipid molecules
- tails= hydrophobic (water-fearing)
- heads= hydrophilic (water-loving)
- protein channel
Substances that pass through the membrane easily:
1. Water
2. Oxygen
3. Carbon dioxide
These are all small molecules that are not ionically charged.

Substances that require assistance to pass through the membrane:
1. Large molecules (protein, glucose, etc.)
2. Ions (charged atoms)

diffusion: a movement of a substance down a concentration gradient (from an area where it is more concentrated to an area where it is less concentrated)
- move from an area where they are "common" to an area where they are "scarce"
- diffusion controls the movement of oxygen and carbon dioxide across the membrane

As you breathe out Carbon DIoxide and the concentration lowers in your bloodstream, CO2 will move from inside the cell (where there is a high concentration) to outside the cell where the concentration is low.

As the concentration lowers and the cell uses oxygen, oxygen moves from the bloodstream where there is a high concentration into the cell.

Osmosis: diffusion of water across a selectively permeable membrane from an area where the concentration is high, to an area where the concentration is low.
- dependent on solute concentration
- solution: solute + solvent
- in the body, water is the solvent
- solutes= ions, glucose, amino acis, etc.

- low electronegativity valves
- they want to lose electrons and not gain them
- high electronegativity valves
(see notes for drawings)

Polar Electron= elements must share electrons

1. hydrogen
2. carbon

Slight charge of the phosphate group makes the head of the phospholipid slightly attracted to the polar water molecules