Transport Demo 1: Tea bag Predict! Observe! Explain!

Demo 2: Body Spray Predict! Observe! Explain!

Passive Transport: Diffusion & Osmosis Concentration gradient – different concentrations across a distance Molecules move from high to low concentration

Driven by kinetic energy (motion energy) Molecules constantly moving “down gradient” Equilibrium – concentration same throughout until reach

More about water (osmosis)… Diffuses across concentration gradient (NO energy required) High Low Concentration Osmotic direction – depends on concentration of solute on both sides of membrane

Demo 3: raisins Predict! Observe! Explain!

Where do you think the water goes? In ? Out? Doesn’t move??? 3 kinds of environments Where do you think the water goes? In ? Out? Doesn’t move??? Hypertonic – concentration of solute greater outside cell

Where do you think the water goes? In ? Out? Doesn’t move??? Hypotonic – concentration solute greater on inside of cell

Where do you think the water goes? In ? Out? Doesn’t move??? Equal concentrations, equilibrium 3. Isotonic – equal concentration in and out of cell; molecules move at equal rate

1. 2. 3.

Plasmolysis – shrinking of cell membrane, response to hypertonic solution Red Onion Cells Red Onion Cells – hypertonic solution

Simple Diffusion & Osmosis Cell membrane is selectively permeable: Small, non-lipid soluble molecules (water) Look at the membrane model again. How do you think the following materials get in/out?: Small, lipid soluble molecules (hydrocarbons) Macromolecules (starches) Large, nonpolar molecules (glucose)

Facilitated Diffusion Non-lipid soluble molecules transported by carrier proteins High Low concentration, NO energy: PASSIVE

Ion Channels Proteins transport ions from high to low concentration **SPECIFIC!!! Each ion has own type of channel** Some channels always open, others gated