M. Tweedie College/Honors Biology

First, Some Vocabulary!!!! Concentration gradient: the difference between the HIGH and LOW concentration areas (tells you direction)

More Vocabulary!!!! Isotonic – same concentration as inside the cell Hypertonic – higher concentration outside the cell Hypotonic – lower concentration outside the cell

Passive Transport Simple Diffusion – movement of molecules (through the membrane) from an area on High concentration to Low concentration ****SEE PPT #1*** Osmosis – the diffusion of water through a membrane (water needs HELP!!!!) Protein that helps is called AQUAPORIN Facilitated Diffusion – movement (without energy input) of non-membrane soluble or larger particles with the help of membrane proteins (CHANNELS)

OSMOSIS Water will move from a high water concentration (LOW solute) to low water concentration (HIGH solute) Isotonic solutions will have no net movement of water!

What happens to living cells when they are not in isotonic solutions? Hypertonic solutions (like ocean water)– water will move out of the animal cell and it will shrink Hypotonic solutions (like fresh water) – water will move into the animal cell and it will burst (lysis) What about PLANT CELLS? Remember Turgor Pressure?

Facilitated Diffusion If substance is to big, or hydrophilic (polar) Still moves from HIGH to LOW = NO ENERGY!!!!! Uses protein channels or gates