Chapter 7

Chapter 7 - 1. 2. Chapter 7 Life at the Edge (Overview) a....

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1. Chapter 7 2. Life at the Edge (Overview) a. Plasma membrane exhibits selective permeability (allows some substances to cross more easily than others) 3. Cellular membranes are fluid mosaics of lipids and proteins (Concept 7.1) a. Membranes are made up of mostly lipids , proteins , and carbohydrates b. Most abundant lipids are phospholipids c. Phospholipids are amphipathic (have hydrophilic and hydrophobic parts ) d. Membrane is a " fluid structure " with a " mosaic " of various proteins embedded in or attached to a double layer (bilayer) of phospholipids A. Membrane Models: Scientific Inquiry a. This section just talks about the ever-changing model for membranes (not important ) B. The Fluidity of Membranes a. Membranes are held together primarily by hydrophobic interactions b. Hydrophobic interactions are weaker than covalent bonds c. Most of the lipids and some of the proteins can shift about laterally d. Adjacent phospholipids switch positions about 100,000,000 times per second e. Although proteins are larger than phospholipids, they sometimes drift as well f. A membrane can remain fluid as temperature decreases until the tightly- packed membrane solidifies g. Membranes with phospholipids that are made up of a lot of unsaturated hydrocarbon tails do not solidify as easily because the kink in the unsaturated hydrocarbon does not allow them to pack tightly h. Cholesterol restrains phospholipids movement, hinders the close packing of phospholipids, and lowers the temperature required for the membrane to solidify i. Membranes must be fluid to function properly C. Membrane Proteins and Their Functions a. Integral proteins penetrate the hydrophobic core of the lipid bilayer b. Peripheral proteins are not embedded in the lipid bilayer but are appendages loosely bound to the surface of the membrane D. The Role of Membrane Carbohydrates in Cell-Cell Recognition a. Cell-cell is the cell's ability to distinguish one type of cell from another b. Membrane carbohydrates that are covalently bonded to lipids are called glycolipids c. Membrane carbohydrates that are covalently bonded to proteins are called glycoproteins d. Human blood types reflect variation of carbohydrates on the surface of red blood cells E. Synthesis and Sidedness of Membranes a. This stuff is relatively unimportant and talks about what happens when organelles fuse with the plasma membrane. Yawn.
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2. Membrane structure results in selective permeability (Concept 7.2)
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This note was uploaded on 08/22/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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Chapter 7 - 1. 2. Chapter 7 Life at the Edge (Overview) a....

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