Cellular Transport

Diffusion the net movement of molecules from an area of high concentration to an area of low concentration Example: the spread of brownies through the house as they bake. Concentration Gradient - a gradual change in the concentration of solutes in a solution as a function of distance through a solution.

Cellular Transport Osmosis– the diffusion of water Water moves across a plasma membrane from an area of HIGHER concentration to an area of LOWER concentration

Question What is Osmosis?

Solution– mixture of two parts: solute & solvent   solute– the molecules that are dissolved solvent – the molecules they are dissolved IN

solutions Isotonic solution a. solution has the same concentration of solute molecules as the cell b. solution remains UNCHANGED can even burst!)

Hypertonic solution a. solution has greater concentration of solute molecules than the cell b. cell looses water and shrinks Hypotonic solution a. solution has a smaller concentration of solute molecules that the cell b. cell gains water and swells (can even burst!)

Question What happens to a cell in a hypertonic, hypotonic and isotonic solution?

Cell Transport Passive Transport – cell uses no energy to move substances across cell

Cellular Transport Facilitated Transport – transport proteins help substances move across the membrane 

Active Transport– movement of molecules that REQUIRES ENERGY Molecules can move across a plasma membrane or against the concentration gradient (from lower concentration to higher concentration)

Question What is the difference between passive and facilitated transport?

Movement of Large Molecules Endocytosis- material engulfed by a portion of the plasma membrane Phagocytosis (food), pinocytosis(water) Exocytosis - cell expels wastes