Movement Through the Cell Membrane

Cell Membrane The thin flexible barrier around the cell that regulates what enters and leaves. Selectively permeable- some substances can pass and others cannot

Cell membrane is made up of: Carbohydrates- act as chemical identification cards (NAME TAGS) for cells to identify one another. (Security) Lipid bilayer- two layers of fat (Fence) Protein channels- that move materials across. (Gates) Watch

Diffusion (Passive Transport) The movement of molecules from an area of high concentration to an area of low concentration. Does not require energy! Equilibrium (Think equal)-When concentration of molecules inside/outside cell is about equal. Watch

Facilitated Diffusion (Passive Transport) When molecules are too large to pass through membrane lipids carrier proteins (protein channels) help move molecules from high to low concentration No cell energy used.

Diffusion Animation http://www.phschool.com/atschool/phbio/active_art/diffusion/index.html

Osmosis (passive transport) Diffusion of water across a selectively permeable membrane. Does not require energy Watch

Osmosis Animation http://www.phschool.com/atschool/phbio/active_art/osmosis/index.html

Active Transport (uses cell energy) Endocytosis-(think enter) -when cells ingest materials too big to pass through the membrane (macromolecules, large particles, other cells). EX: phagocytosis

Active Transport (cont.) Exocytosis-(think exit)- substances removed from cell by vesicles Remove: proteins, toxins, waste products

Active Transports http://www.phschool.com/atschool/phbio/active_art/active_transport/index.html

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic Solution Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)