Cell Membranes. The Cell Membrane. Cell Membrane : . At Very High Magnification & in color. Phospholipid Molecule Model. phosphate (hydrophilic/polar). glycerol fatty acids (hydrophobic/nonpolar). Membrane Structure. Hydro Philic/philia Phobic/phobia Polar=soluble in water.
At Very High Magnification
& in color
fatty acids (hydrophobic/nonpolar)
HydroPhilic/philiaPhobic/phobiaPolar=soluble in water
Every cell is encircled by a membrane and most cells contain an extensive intracellular membrane system. Membranes fence off the cell's interior from its surroundings. Membranes let in water, certain ions and substrates and they excrete waste substances. They act to protect the cell.
Without a membrane the cell contents would diffuse into the surroundings, information containing molecules would be lost and many metabolic pathways would cease to work:
The cell would die!
P-Lipids are represented like this
Fluid Mosaic Model - lipids arranged in bilayer with proteins embedded or associated with the lipids.
What color are the lipids?
What color are the integral proteins?
What color are the peripheral proteins?
Frey and Edidin
allows for different conditions between inside and outside of cell
subdivides cell into compartments with different internal conditions
allows release of substances from cell via vesicle fusion with outer membrane:
Solution = solute + solventSolute-- the thing being dissolvedSolvent--does the dissolvingkool-aid chocolate milkTerms that refer to solute:HyperHypoIso
2. What diffuses?
4.Is this diffusion or osmosis?
5.Which side is hypertonic?
6.Which side is hypotonic?
7.Why doesn’t the sugar diffuse?
Movement of water across a semi-permeable barrier.
Example: Salt in water, cell membrane is barrier. Salt will NOT move across membrane, water will.
Hypotonic solutions- swell cells
“Hypos make hippos”
Cytolysis in Animal Cells
Turgor Pressure in Plant Cells
For more animations view: http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm
View frozen frogs at:
How did the frog use the principles of osmosis and diffusion to survive the winter? Make sure you use the following terms appropriately in your description: hypertonic, hypotonic, solute, solvent, diffusion, osmosis, cytolysis, crenation, isotonic and semi-permeable membrane.
A. Facilitated Diffusion
Assist in diffusion process.
Solutes go from High conc to Low conc.
Examples: Glucose transporters
Movement from region of low free energy(low concentration) to regions of high free energy (high conc.)
Requires energy input