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Cell membranes

Cell membranes

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Cell membranes

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  1. Cell membranes

  2. Cell membrane structure • Phospholipid bilayer • Glycerol-Hydrophilic; Fatty acid-Hydrophobic • Fluid mosaic model • Lipid bilayer, Proteins, Carbohydrates, steroids

  3. Reading quiz (pass HW, assignment sheet to center. You should also have WB __, 27 and lab report template (after WB 1). Put everything else under your desk so you are ready for the lab) • 1. Diffusion involves the movement of molecules from areas of ____ concentration to ____ concentration • 2. Which of the following best represents a concentration gradient? • There is a uniform amount of perfume in the entire classroom • There is more perfume in one area of the classroom than the rest of the classroom • 3. Osmosis is the diffusion of the molecule ____ across a ______

  4. Diffusion and osmosis • Diffusion: Process of substances moving from higher concentration to lower concentration (does not require energy) • Osmosis: Diffusion of water through a selectively permeable membrane • Equilibrium: Dynamic state when rates of movement remain constant • Tutorial

  5. Reading quiz • Match the following words with their meaning • 1. Hypertonic 2. Hypotonic 3. Isotonic 4. Equilibrium • a. state where movement occurs in both directions at the same rate • b. Has a relatively lower concentration of solutes • c. Has a relatively higher concentration of solutes • d. Has the same concentration of solutes as the surrounding

  6. Tonicity

  7. Facilitative and active transport • Passive: Small molecules • Alcohol, water, gases, small lipids • Facilitated: Some larger molecules, protein needed to facilitate transport • Require energy? • No! High  low concentration

  8. How do materials enter/leave the cell? • Glucose will go through facilitated diffusion from higher to lower concentration • What if glucose needs to be pumped out of the cell from lower to higher concentration • Requires energy from ATP!

  9. Endocytosis versus Exocytosis