Cell Boundaries and Movement

Cell Barriers Cell membranes – Structure: contain a flexible lipid bilayer with imbedded protein molecules and carbohydrate molecules – Function: Substances move across the cell membrane through A.) lipid bilayer B.) protein channels C.) assistance of protein molecules D.) Processes of endocytosis and exocytosis

Cell Barriers Cell Walls – Structure: made mostly of tough carbohydrate fiber called cellulose – Function: Cell walls support and protect cells; cell walls are porous and allows substances to move through easily

Types of Movement Through Cells A.) Diffusion B.) OSMOSIS C.) Facilitated Diffusion D.) Active Transport

REMEMBER DIFFUSION?

WATER IS SO SPECIAL. WHEN IT DIFFUSES ACROSS A SEMI-PERMEABLE MEMBRANE…. IT HAS A SPECIAL NAME: OSMOSIS

REMEMBER: WHICH WAY DO SOLUTES WANT TO MOVE? FROM ______________ concentration to ______________ concentration. THE SAME CAN BE SAID ABOUT WATER.

Osmosis The diffusion of water across a cell membrane Types of osmotic solutions – Hypotonic – Isotonic – Hypertonic

Which way will the water move?

What’s up with these blood cells?

3 Types of Solutions

Hypotonic Solution the solution has a lower solute concentration than the cell so water moves into the cell causing plant cells to swell and animal cells to swell and burst Lower solute concentration outside cell Animal Cell

Isotonic Solution The concentration of solutes is equal inside and outside the cell so water moves across the membrane in both directions maintaining cell size Animal Cell Equal solute concentration inside and outside cell

Hypertonic Solution The solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to shrivel. Animal Cell higher solute concentration outside cell

Time for your brain to hurt. #1 #2#3 WHAT SOLUTION ARE TUBES #1, #2, & #3 in? ISOTONIC, HYPERTONIC, HYPOTONIC?

PLANT CELLS HYPERTONIC ISOTONIC HYPOTONIC