Diffusion & Osmosis

Cell Theory 1. All living things are made of one or more cells. 2. Cells are the basic units of structure and function in organisms. 3. All cells arise from existing cells.

Eukaryote- organism whose cells have a nucleus. Prokaryote- a single celled organism that lacks a nucleus and other internal compartments. Eukaryote- organism whose cells have a nucleus.

The Plasma Membrane - Define Diffusion Gateway to the Cell

Structure of the Cell Membrane

Photograph of a Cell Membrane

Define Diffusion

Define Diffusion The movement of molecules from a area in which they are highly concentrated to a area in which they are less concentrated.

Solute moves DOWN concentration gradient (HIGH to LOW)

Draw a diagram of an example of diffusion we saw in class.

See an animation of diffusion here: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

Define osmosis

Define osmosis   Osmosis- the diffusion of water through a selectively permeable membrane. http://www.usd.edu/~bgoodman/Osmos.htm

In Other words…   This means that water would cross a selectively permeable membrane from a dilute solution (less dissolved in it) to a concentrated solution (more dissolved in it). http://www.usd.edu/~bgoodman/Osmos.htm

See an animation of osmosis here: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html http://www.usd.edu/~bgoodman/Osmos.htm

Lets look even further… In this picture a red blood cell is put in a glass of distilled water.  Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS.  In this case too much water enters and the cell swells to the point of bursting open.  In the end pieces of cell membrane are left in the water. http://www.usd.edu/~bgoodman/Osmos.htm

Permeable- allows most all things to pass through Semi permeable- allows some things to pass through Impermeable- things can not pass through

Why are osmosis & diffusion important? This membrane is a complex structure that is responsible for separating the contents of the cell from its surroundings, for controlling the movement of materials into and out of the cell, and for interacting with the environment surrounding the cell.

Passive Transport- Movement across cell membrane that does NOT require energy from the cell Active Transport- Movement across cell membrane that requires energy from the cell

Be ready to explain in your own words the definition of diffusion and osmosis.