* Nucleic Acids
Elements C, H, O, N, P

Store genetic information

Examples: DNA, RNA


* Cells
All have the following features: cell membrane, cytosol, DNA, ribosomes

| comparison                                          | prokaryotic | eukaryotic          |
| nucleus and other membrane-bound organelles present | no          | yes                 |
| size                                                | smaller     | larger              |
| cell structure                                      | unicellular | multi/uni-cellular  |
| examples                                            | bacteria    | plants,animals,etc. |

** Endomembrane System (Organelles with membranes)
nucleus, endoplasmic reticulum, golgi apparatus, lysosomes, vesicles, vacuoles, cell membrane

** Phospholipid molecule
hydrophilic head, two hydrophobic tails

** Cell membrane
Components: phospolipid bilayer, proteins

Feature: semipermeable

** Cell transport processes can be passive or active
Passive processes:

+ Do not require the cell to expend energy
+ Net movement from high to low concentration; "with" or "down" the gradient ("difference in concentation")

| Passive Transport Process | Description                                               | Net Direction of Molecule Movement | Molecules transported? |
| Diffusion                 | molecules spread evenly into space                        | High -> low [H] -> [L]             | O_2, CO_2              |
| Facilitated Diffusion     | molecule movemement is assisted by proteins               | ""                                 |                        |
| Osmosis                   | movement of water across a selectively permeable membrane |                                    |                        |
|                           | from high concenctration of water to low concentration    |                                    | H_2O                   |

** Solute
concentration in solution:

| hypertonic | greater solute concreation |
| isotonic   | equal [solute]             |
| hypotonic  | lower [solute]             |