CELLULAR TRANSPORT!

CELLULAR TRANSPORT Passive vs. Active Passive cellular transport: No energy (ATP) Required A. Diffusion-moves gases across the membrane from high to low! – Oxygen, carbon dioxide, and fume particles B. Osmosis – movement of water from high to low Isotonic : no net movement Hypotonic: water in Hypertonic: water out – Remember  “SALT SUCKS!!”

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)

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) Result: Water moves from inside the cell into the solution: Cell shrinks Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Osmosis shrinks

Hypotonic Solution 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!

Osmosis in Elodea cells 1: Elodea + pure water Notice the chloroplast at the edge of the cell wall 2: isotonic + tap water Notice the chloroplasts are evenly spaced 3: Elodea + salt Notice all chloroplasts in the center; membrane pulled away from cell wall membrane vacuole chloroplasts Cell wall

C. Facilitated Diffusion The movement of particles from areas of HIGH concentrations to areas of LOW concentration with the HELP of a TRANSPORT protein. Like regular diffusion, this is a type of PASSIVE transport and does NOT require energy! Animation: How Facilitated Diffusion Works Animation: How Facilitated Diffusion Works

D. Active Transport Movement of particles AGAINST the concentration gradient from areas of LOW to areas of HIGH concentration. This does require ENERGY!! Example: Ion Pump lates/student_resources/shared_resources/ani mations/ion_pump/ionpump.html lates/student_resources/shared_resources/ani mations/ion_pump/ionpump.html

E. BULK transport…when molecules are too BIG to pass… 1. ENDOCYTOSIS: movement of a substance INTO the cell – Phagocytosis (food in) – Pinocytosis (fluid in)

PHAGOCYTOSIS Watch this animation!! nimat/cellstructures/phagocitosis.swf - nimat/cellstructures/phagocitosis.swf - Amoeba Horror!!!

PINOCYTOSIS Watch this animation – Endocytosis - Animation of Pinocytosis

2. EXOCYTOSIS Movement of a substance OUT of the cell e/BIOBK/exocyt.gif e/BIOBK/exocyt.gif