Biology Chapter 7 Objectives

Biology Chapter 7 Objectives - Chapter 7 Membrane Structure...

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Chapter 7 Membrane Structure and Function Membrane Structure 1. Phospholipids are amphipathic molecules because it has both a hydrophilic and hydrophobic region. 2. Free-fracture techniques reveal that proteins are embedded in the phospholipid bilayer of the membrane. It also reveals that the interior of the bilayer appears cobblestoned, with protein particles interspersed in a smooth matrix. 3. Membranes are held together primarily by hydrophobic interactions. Most of the lipids and some of the proteins can drift laterally across the plane of the membrane. The lateral movement of phospholipids within the membrane is rapid. A membrane remains fluid as temperature decreases until the phospholipids settle into a closely packed arrangement and solidifies. Also, if a membrane is rich in phospholipids with unsaturated hydrocarbon tails, the membrane is more fluid due to the kinks in the tails where the double bonds are located. 4. Cholesterol resists changes in membrane fluidity with temperature change. Since the steroid cholesterol is wedged between phospholipid molecules in the plasma membrane, cholesterol makes the membrane less fluid by restraining the movement of phospholipids. By hindering the close packing of phospholipids, it lowers the temperature required for the membrane to solidify. It can be thought of as a temperature buffer, due to the resistance in changes in temperature. Traffic Across Membranes 5. Integral proteins penetrate the hydrophobic core of the lipid bilayer. Peripheral proteins are not embedded in the lipid bilayer at all, they are appendages loosely bound to the surface of the membrane and often to the exposed parts of integral proteins. 6.
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This note was uploaded on 08/29/2009 for the course BIOL 101 taught by Professor Sakji during the Fall '08 term at Linn Tech.

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Biology Chapter 7 Objectives - Chapter 7 Membrane Structure...

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