Structure of the Cell membrane Fluid Mosaic Model: Bilayered: phospholipids with proteins throughout. Selectively Permeable: allows some materials to pass through and prevents others from passing.

Passive Transport – cell does not use energy. Use of transport proteins.

Diffusion Movement of a substance from an area of high concentration to low concentration Concentration Gradient:

Diffusion Equilibrium:

Osmosis Diffusion of water through a semi-permeable membrane

Affects of solutions on cells 3 types of solutions Isotonic Hyoptonic Hypertonic

Osmosis in Plants Turger Pressure: cell swells due to increase in water moving in – hypotonic solution Plasmolysis: water moves out of cells causing wilting – hypertonic solution

osmosis

Facilitated Diffusion Use of proteins to move substances into or out of the cell.

Active Transport Requires energy Works against or up the concentration gradient (low concentration to high) Examples of : sodium/potassium pump Endocytosis : phagocytosis and pinocytosis Exocytosis – remove waste from interior

sodium potassium pump Active trans – 3 sodium ions are pumped out of the cell and 2 potassium ions are pumped in.

endocytosis The movement of a large substance into a cell

Phagocytosis Type of endocytosis The cell engulfing large “food”, solid material

Pinocytosis Form of endocytosis When the cell engulfs liquid particles.

Exocytosis - http://www.stanford.edu/group/Urchin/GIFS/exocyt.gif