1. 1.3 & 1.4 Cellular Membranes

2. Read & Consider 1.3.1 – 1.3.3 What do you know? What questions do you have?

3. Cells are surrounded by water inside and out. Membrane behavior is dictated by interactions with water. Polar Nonpolar

5. The diagram should include: Phospholipid bilayer Cholesterol Glycoproteins Integral proteins Peripheral proteins academic.brooklyn.cuny.edu

7. Watch – History of Cell Membrane up to Gorter and Grendel’s 1925 discovery “Insights into cell membranes via dish detergent”Insights into cell membranes via dish detergent Davson and Danielli’s “Fat Sandwich Model” – accepted until 1972 Singer and Nicolson’s “Fluid Mosaic Model” – accepted today

8. Read & Consider 1.4.1-1.4.2 What do you know? What questions do you have? Compare and contrast diffusion and osmosis.

9. Diffusion: passive movement of particles from a region of high concentration to a region of low concentration.

10. Osmosis: passive movement of water molecules from a region of lower solute concentration to a region of higher concentration. Isite.lps.org

11. Simple Diffusion –there is no expenditure of energy in moving the molecules across the membrane. Facilitated Diffusion – larger molecules move passively through the membrane via channel proteins. sjcabiology.wikispaces.com

12. Molecules moving from low to high concentration must be actively moved. Kenpitts.net Video

13. A transport mechanism for the movement of large quantities. Exocytosis: vesicle membrane fuses with the plasma membrane. Endocytosis: a vesicle is formed by the in folding of the plasma membrane. Material Transport

14. o Phospholipid molecules can change places in the horizontal plane (creates fluidity). o Molecule exchange in the vertical plane DOES NOT occur (maintains integrity). Video

15. Inner Life of a Cell 2007 – the President and Fellows of Harvard College

16. Tissue or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis. Complete the exploration phase for the lab with the following aim: To determine the osmolarity of an unknown substance by bathing samples in hypotonic and hypertonic solutions.