Chapter 7: Membrane Structure and Function AP Biology Mrs. Ramon

Plasma Membrane Boundary that separates living cell from environment Controls chemical traffic into and out of the cell Selectively permeable

Early Models Sandwich Model, Davson and Danielli (1935) Phospholipid bilayer between two layers of globular protein

Fluid Mosaic Model Singer and Nicholson (1972)

Fig. 7-7 Fibers of extracellular matrix (ECM) Glyco- Carbohydrate protein Carbohydrate Glycolipid EXTRACELLULAR SIDE OF MEMBRANE Figure 7.7 The detailed structure of an animal cell’s plasma membrane, in a cutaway view Cholesterol Microfilaments of cytoskeleton Peripheral proteins Integral protein CYTOPLASMIC SIDE OF MEMBRANE

Passive Transport Characteristics Types No energy is required [High]  [low] http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html Types Diffusion Facilitated Transport Osmosis

Active Transport Characteristics Requires energy [low]  [high] Transport proteins act as “pumps” http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html

Moving LARGE Molecules Exocytosis Endocytosis Three types: Phagocytosis Pinocytosis Receptor-mediated endocytosis

Environment: 0.01 M sucrose “Cell” 0.01 M glucose 0.01 M fructose Fig. 7-UN3 Environment: 0.01 M sucrose 0.01 M glucose 0.01 M fructose “Cell” 0.03 M sucrose 0.02 M glucose

You should now be able to: Define the following terms: amphipathic molecules and diffusion Explain how membrane fluidity is influenced by temperature and membrane composition Distinguish between the following pairs or sets of terms: peripheral and integral membrane proteins; osmosis, facilitated diffusion, and active transport; hypertonic, hypotonic, and isotonic solutions Explain how transport proteins facilitate diffusion Explain how large molecules are transported across a cell membrane Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings