All Cells: Cell Membrane Cell Wall What are the Cell Boundaries??? Some Cells, Mostly PLANT:

Cell Membrane aka. THE GATE KEEPER Function: regulates what enters and leaves the cell Function: provides protection and support aka. THE GATE KEEPER

Hydrophilic To Fear Hydrophobic TO LOVE The phospholipid bilayer Function: give membranes a flexible structure that forms a STRONG barrier between the cell and its surroundings Hydrophilic TO LOVE To Fear Hydrophobic

Cell Wall: found in plants, algae, and many prokaryotes Porous: allow water, oxygen, carbon dioxide, and other substance to pass MAIN Function: provide support and protection for the cell Made mostly from: carbohydrates :the polysaccharide…Cellulose

Diffusion The process in which particles move from a HIGHER concentration to a LOWER concentration of particles NO ENERGY is required The particles are working toward EQUILIBRIUM

Diffusion is ALWAYS occurring Molecules that are dissolved in water take up space SALT IS NOT ALLOWED TO DIFFUSE THROUGH THE MEMBRANE

Question #1: If a solution is 10% salt, what percentage of the solution is water? 90%

This cell’s cytoplasm is 95% water. Question #2: This cell’s cytoplasm is 95% water. so how much is dissolved “stuff”? The cell is placed in a 10% salt solution. So how much is water? WHAT HAPPENS TO THE CELL? 10% salt 90% water 95% water 5% “stuff”

Diffusion Problems Step 1: Determine the concentrations of water on both sides of the membrane Step 2: State the direction of the diffusion that is occurring

when substances can pass through the membrane What does it mean to be permeable? What does it mean to be impermeable? What does it mean to be selectively permeable? when substances can pass through the membrane when substances can't pass through the membrane SOME substances can pass through the membrane

Have you ever learned by OSMOSIS? The diffusion of WATER through a selectively permeable membrane PROBABLY NOT!

Osmosis ENERGY http://www.usd.edu/~bgoodman/Osmos.htm

Important Terms Isotonic: the concentration of solutes is the same inside and outside the cell Hypertonic: Solution has a higher solute concentration than the cell Hypotonic: Solution has a lower solute concentration than the cell

Osmosis in Red Blood Cells Normal RBC Shrunken RBC

Osmotic Pressure is building!!!

Facilitated Diffusion High Concentration to Low concentration NO ENERGY required The cell membrane protein facilitates movement http://www.d.umn.edu/favicon.ico In your body: Red blood cells (RBC’s) have a cell membrane protein with an internal channel that only allows glucose to pass through

Active Transport ENERGY LOW concentrations HIGH concentrations Animations Requires Movement of molecules from areas of to areas of ENERGY LOW concentrations HIGH concentrations

A few examples of Active Transport Endocytosis: Taking materials IN Examples of endocytosis Phagocytosis: cell eating Endocytosis - Animation of Phagocytosis Pinocytosis: WATER Endocytosis - Animation of Pinocytosis Exocytosis: Letting Materials OUT http://www.stanford.edu/group/Urchin/GIFS/exocyt.gif

Comparing Passive and Active Transport