Chapter 7 - Cellular Membrane & Transport Notes

Chapter 7 - Cellular Membrane & Transport Notes -...

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AP Biology—Chapter 7 Lecture Notes The Plasma Membrane and Transport As you have already learned, the plasma membrane selectively regulates the movement of molecules into and out of the cell. It does not really protect the cell, because many undesirable substances are capable of diffusion into cells. In Eukaryotic cells, membrane bound organelles behave in similar fashion to the plasma membrane. The Fluid Mosaic Model --the membrane is a “sea” of phospholipids in which are floating carbohydrates of different buoyancy; this suggests that lipid and protein molecules are capable of moving around within this “sea.” --proteins that extend through the entire membrane must have both hydrophobic and hydrophilic regions; they must be amphipathic --many proteins and lipids are also attached to carbohydrates, which aid in cell recognition and communication --degree of membrane fluidity is determined by the type of phospholipids present; if the phospholipids contain unsaturated hydrocarbon tails, they are more fluid at lower temperatures. --cholesterol is located within the lipid bilayer and helps maintain fluidity at high and low temperatures --there are two main types of proteins in the cell membrane: 1. Integral proteins —penetrate the hydrophobic region of the membrane; many are transmembrane (they extend through both sides of the membrane) 2. Peripheral proteins —are loosely bound to the surface of the membrane, often to the exposed parts of integral proteins --proteins can be partially attached to the cytoskeleton on the cytoplasmic side of the membrane and to the ECM on the cell exterior Roles of Membrane Proteins 1. Transport 2. Enzymatic Activity 3. Signal Transduction 4. Cell-cell Recognition 5. Intercellular Joining 6. Attachment to Cytoskeleton and ECM Two Types of Membrane Carbohydrates 1. Glycoproteins—carbohydrates bonded to proteins on the membrane 2. Glycolipids—carbohydrates bonded to lipids on the membrane
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This note was uploaded on 02/14/2012 for the course BIO 151 taught by Professor Grinblat during the Fall '08 term at Wisconsin.

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Chapter 7 - Cellular Membrane & Transport Notes -...

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