1. Eukaryotic Cell Membrane

2. Cell Membrane Cell membrane: the flexible boundary of a cell (also called a plasma membrane) It separates a cell from its surroundings. It allows nutrients to enter and waste to be removed.

3. Cell Membrane Homeostasis: maintaining a healthy balance The cell membrane allows some molecules into the cell and keeps others out.

4. Cell Membrane Selective permeability: allowing only certain molecules to enter and leave the cell Selective permeability is like a screen on a window

5. Cell Membrane What gets in? H 2 O freely enters cell O 2 in,CO 2 out Na and Ca at certain times in certain amounts Waste leaves but can’t reenter

6. Membrane Structure Phospholipid: lipid with a glycerol backbone and two fatty acid chains, and a phosphate group

7. Membrane Structure The polar head is hydrophilic: it likes water Fatty acid tail is hydrophobic: it does not like water. They form a bilayer

8. Membrane Structure

9. The cell membrane also contains proteins to help support the cell structure. Cholesterol to keep the fatty acid tails from sticking together

10. Membrane Structure Fluid Mosaic Model: the organization of the cell membrane. Fluid because it is not fixed in a particular spot Mosaic because of the patterns the proteins make

11. Membrane Structure Proteins in the membrane function as: Transport proteins: moving molecules across the membrane Identify chemical signals