1. The cell membrane, diffusion and osmosis
Caylor
Day Five
The cell membrane, diffusion and osmosis

2. Journal 5 Complete the Venn diagram below: Animal Cell Plant Cell 1.2. 1. 2. 1. 2.

3. Describe the functions of the cell membrane.
Provides boundary for cell
Controls flow in and out of cell
Selectively permeable
Maintains homeostasis: balance within the cells

4. Relate the structure of the cell membrane to its function.
Membrane is a lipid bilayer
Made up of molecules which are free to move; called fluid-mosaic
Phospholipids: fatty areas that attract and repel water; makes membrane behave like a fluid
Embedded proteins: determine which particles can pass through
Also serve as recognition markers
Form channels from one side of the cell to the other

5. Compare diffusion and osmosis.
DIFFUSION: movement of particles from high concentration to low concentration
Causes substances to move across membrane
Does not require the cell to use energy
Substances move across membrane until there are equal amounts on either side: EQUILIBRIUM

6. OSMOSIS: diffusion of water through a membrane
How osmosis works: water moves from where there is a lot to where there is a little until equilibrium is reached
Osmosis exerts pressure (OSMOTIC PRESSURE) which can cause some problems for certain cell swelling
Higher Concentration
of Water
Water molecules
Lower Concentration
of Water
Sugar molecules

7. Quiz 5 Which of the following is NOT found in the plasma membrane?
a. phospholipids b. proteins c. plasma
If a cell only lets certain things in and certain things out, it is referred to as ___.
a. permeable b. selectively permeable c. osmotic
___ is the movement of particles from high concentration to low concentration.
a. diffusion b. selectively c. osmosis
Since the plasma membrane moves around the surface of the cell, it is called a ___ model.
a. fluid-mosaic b. passively transported c. static
If a salt water worm is placed in a container of fresh water, what would happen to the worm?
a. it would shrink up b. nothing c. it would swell up
Quiz 5