Cell Membrane Notes Chapter 7-3

I. Cell Membrane – CM (plasma membrane) A. Its job is to control what enters or exits the cell in order to maintain homeostasis (balance) B. Its Semi-Permeable: only some things are able to pass through, but not others –1. Ex: fishing net

II. Structure A. It’s a Phospholipid Bilayer 1. 2 layers of lipids

–2. Phospholipid = Lipid with a phosphate (Lipid =Glycerol & Fatty Acid) a) Polar Head = Glycerol with a Phosphate attached –1) hydrophilic: water loving b) Nonpolar Tail = 2 Fatty Acids –1) hyrdophobic: water hating

B. It is a Fluid-Mosaic Model –1. It acts like a fluid and made up of lots of tiny parts like a mosaic

C. Other Contents in the CM: –1. Cholesterol: Spacers between phospholipids to keep them spaced out

–2. Proteins: a) Transport proteins transport items across the membrane. b) Inner Surface Proteins attach to the cytoskeleton giving the cell shape, flexibility & movement

c) Identification proteins are attached to carbohydrates on the surface of the cell –1) helps in cell identification

Types of Membrane Transport: Overview