Structure of the Cell membrane Fluid Mosaic Model

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 semipermeable 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