Cell Membrane Structure: made of a phospholipid bilayer and proteins. the fluid mosaic model.
Equilibrium: even distribution of molecules.
Solution: mixture in which solute particles are evenly distributed in a solution.
Solute: substance dissolved in solvent.
Solvent: liquid in which solute is dissolved.
Ways Substances Move Across Membranes
I. Passive Transport: does not require energy.
A. Diffusion: random movement of molecules from a region of high concentration to low concentration.
B. Osmosis: movement of water through a membrane from a region of high concentration to a region of low concentration.
1. hypertonic: contains higher concentration of solutes.a. plasmolysis: cell will shrivel as it loses water.
2. hypotonic: contains lower concentration of solutes.
a. cytolysis: animal cell bursts as water enters the cell.b. turgor pressure: increase of water pressure inside a plant cell.
3. isotonic: contains same concentration of solutes.
C. Facilitated Diffusion: movement of molecules from a region of high concentration to low concentration using a helper molecule.
II. Active Transport
A. Endocytosis: taking material into the cell.
1. pinocytosis: cell drinking.2. phagocytosis: cell eating.
B. Exocytosis: putting material outside the cell.