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5.1 Mini Lecture

5.1 Mini Lecture. AP Biology. Which model was correct?. PDQ 1. Singer and Nicholson. PDQ #2. Polar group – phosphate group  negative charge Net negative charge. PDQ #3 Membrane Parts. Add descriptions/functions. Integral Proteins transports molecules across membrane

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5.1 Mini Lecture

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  1. 5.1 Mini Lecture AP Biology

  2. Which model was correct? PDQ 1. Singer and Nicholson

  3. PDQ #2 Polar group – phosphate group  negative charge Net negative charge

  4. PDQ #3 Membrane Parts Add descriptions/functions • Integral Proteins • transports molecules across membrane B. Peripheral Proteins – • transports molecules from protein to protein • do NOT penetrate the membrane • are hydrogen bonded to membrane

  5. PDQ #3 Membrane Parts Add descriptions/functions C. lipid Bilayer • Hydrophilic end of phospholipids • Polar head • Has a negative charge • Hydrophobic end of phospholipids • Nonpolar tail • Cholesterol • Maintain fluidity of membrane • See steroid structure?

  6. PDQ #3 Membrane Parts Add descriptions/functions • Glycolipid • Carbohydrate + lipid • Cell recognition • Glycoprotein • Carbohydrate + protein • Assist in binding of hormones • Oligosaccharides • Small polysaccharides • Cell recognition • Cytoskeleton • Cell shape, movement of organelles

  7. #4. What is meant by the phrase, membranes are asymmetric. • Proteins are embedded asymmetrically across the membrane

  8. #5. What components of the cell membrane contribute to the fluid quality of the cell membrane? • Cholesterol – maintain the fluidity • Fatty acids on hydrophobic portion (nonpolar tails)

  9. Cholesterol • Controls the fluidity of the cell membrane

  10. Phospholipids Phospholipids may differ in: • Fatty acid chain length • Degree of saturation • Kinds of polar groups present

  11. Two important factors in membrane fluidity: Lipid composition—types of fatty acids can increase or decrease fluidity Temperature—membrane fluidity decreases in colder conditions PDQ 6

  12. Proteins • Peripheral membrane proteins lack hydrophobic groups and are not embedded in the bilayer. • Integral membrane proteins are partly embedded in the phospholipidbilayer. PDQ 7. transmembrane protein extends through the bilayer on both sides

  13. PDQ 8. • Amphipathic – has hydrophilic and hydrophobic portions • permanent

  14. 9. Types of amino acid side chains interface with fatty acid chains Nonpolar Hydrophobic Non-charged

  15. 10. Glycoprotein vs. Glycolipid • Glycoprotein – carbohydrate attached to a protein • Glycolipid – carbohydrate attached to a lipid

  16. 11. Roles of carbohydrates on surface of cell membrane • Binding sites for molecules • Help hold adjacent cells together

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