Introduction to... Cell Transport

Semi-Permeable Membrane The cell membrane is semi-permeable Semi-permeable-only certain things can pass through (permeate) it Smaller molecules can pass through. Larger molecules and charged molecules cannot.

Passive vs. Active Transport PASSIVE= **No energy (ATP) needed for movement of certain particles across the membrane in/out of cell. Particles (molecules and ions) move from HIGH to LOW concentration. “Paddling with the current.” Types of passive transport Diffusion Osmosis Passive facilitated diffusion

Which container has the highest concentration of solutes?

Diffusion Move from high to low concentration Occurs until equilibrium is reached. PASSIVE TRANSPORT, SO NO ENERGY REQUIRED FOR PARTICLES TO DIFFUSE!!!

Osmosis Osmosis-diffusion of water PASSIVE, SO NO ENERGY REQUIRED TO DO THIS! Water can go through the semi-permeable cell membrane. High  low Osmosis animation

Hypertonic Environments Osmosis can occur with water going into OR out of the cell, depending on what type of environment the cell is in. Hyper= above/higher Hypertonic- the cell is in a higher solute concentration i.e. saltwater Osmosis- water moves OUT of cell in this environment (highlow). Shrivel and die.

Hypotonic Environments Hypo = under/lower Hypotonic- the cell is in a lower solute concentration i.e. pure water Osmosis- water will move INTO cell in this environment (highlow) Swells with water and bursts. Cell wall prevents plant cells from bursting—like a water balloon in a box

Isotonic Environments Iso = same/equal Isotonic cell environment- equal solute concentration inside and outside the cell i.e. pure blood Water flow in = water flow out Cells remain the same

100% Water, 0% Salt Pure Water 96% Water, 4% salt Concentrated Saltwater 100% Water, 0% Salt Pure Water 98% Water, 2% Salt Blood

Passive Facilitated Diffusion NO ENERGY (ATP) NEEDED! PASSIVE! Some particles are too large to pass through the membrane. Special proteins come to the rescue