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The Cell

The Cell. Movement Across the Membrane. Cell Diagram: College of Dupage. Quiz. 1. What is the type of bond within a single water molecule? 2. A carboxyl group is symbolized by what? 3. Briefly explain what happens in a hydrolysis reaction.

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The Cell

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  1. The Cell Movement Across the Membrane Cell Diagram: College of Dupage

  2. Quiz • 1. What is the type of bond within a single water molecule? • 2. A carboxyl group is symbolized by what? • 3. Briefly explain what happens in a hydrolysis reaction. • 4. Is maltose a monosaccharide, disaccharide, lipid, or protein?

  3. Quiz cont. • 5. Are lipids hydrophobic or hydrophilic? • 6. What is the difference between a saturated vs unsaturated fatty acid? • 7. What does the secondary structure of protein refer to? • 8. How does an enzyme work?

  4. Quiz cont. • 9. What is the difference between filtration and diffusion? • 10. What happens to a rbc in a hypertonic solution? • A hypotonic solution?

  5. C. Fluid Mosaic Model Plasma membrane is oily film made of lipids with diverse proteins embedded in Phospholipid bilayer • Hydrophillic heads facing water on either side of cell membrane • Hydrophobic tails directed to center Proteins -integral or transmembrane -peripheral

  6. Plasma Membranewww.susanahalpine.com/anim/Life/memb.htm

  7. Functions of the Cell Membrane • Defines boundaries of the cell • Governs interactions with other cells • Controls passage of materials into and out of cell

  8. III. Movement Across Membrane A. Selective Permeability Depends on • Size of particle • Solubility in lipids • Charge on particle 4. Carrier molecules in membrane

  9. Movement across membrane occurs through: • Lipid bilayer • Membrane channels • With carrier molecules • In vesicles

  10. Passive vs. Active Transport Requires ___________ • Primary Active Transport • Secondary Active Transport

  11. B. Non-mediated Transport Mechanisms • Diffusion • Osmosis • Filtration • Passive • Requires no energy

  12. Concentration Gradient

  13. B. Non-Mediated Transport Mechanisms DIFFUSION = when molecules move from a higher to a lower concentration. What type of things might affect the rate of diffusion? a. Magnitude of concentration gradient b. Temperature c. Size of diffusing particles d. Viscosity (thickness) of solvent Diffusion Animation: biologycorner.com

  14. Diffusion

  15. Osmosis: Diffusion of water across the membrane Water moves from an area of more water to an area of less water

  16. Osmotic Pressure Whenever dissolved substances such as glucose or protein are confined in a space by a selectively permeable membrane, they can pull water into the compartment by osmosis. The strength of the osmotic pull is directly related to the concentration of the solution. The greater the concentration, the greater the pulling, or osmotic pressure.

  17. Tonicity =the ability of a solution to affect fluid volume and pressure within a cell Environment surrounding cells may contain amounts of dissolved substances (solutes) that are… equal to less than greater than …those found within the cell. Tonicity Isotonic: no net movement of water between cell and environment Hypertonic: a higher concentration of solute. Hypotonic : a lower concentration of solute. Water will always move toward a hypertonic environment!! Diagrams: Cell: College of DuPage Osmosis - www.scienceaid.co.uk/biology/plants/osmosis.html Blood Cells: Mariana Ruiz

  18. Effects of tonicity on RBCs:Water moves from an area of more water to an area of less water www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.htm

  19. Effects of Tonicity on RBCs Isotonic solutions: normal saline (0.9% NaCl), 5%D/W, and Ringer’s solution Under special conditions, hypotonic or hypertonic solutions may be administered IV. Most IV solutions are isotonic.

  20. Filtration- due to a pressure gradient

  21. Mediated Transport Mechanisms Characteristics 1. Specificity- carrier exhibits specificity for certain ligand, just as an enzyme does for its substrate 2. Saturation- once all carriers occupied, adding solutes will not make the process go any faster Three types 1. Facilitated Diffusion 2. Active Transport 3. Bulk Transport

  22. Facilitated Diffusion Passive -Proteins assist in diffusion of molecules across plasma membrane. -Movement only occurs in the presence of a concentration gradient. -Some molecules move across the membrane more quickly if diffusion is facilitated by a carrier molecule.

  23. Web References www.susanahalpine.com/anim/Life/memb.htm www.northland.cc.mn.us/biology/biology1111/animations/passive3.swf http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation_how_osmosis_works.html www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.htm www.education.uoit.ca/lordec/ID_LORDEC/capillary_fluid/capillary_fluid_LO.swf http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation_how_facilitated_diffusion_works.html

  24. Review What are three examples of non-mediated transport mechanisms?

  25. Review What are three examples of non-mediated transport mechanisms? 1. Diffusion 2. Osmosis 3. Filtration

  26. Review What are three examples of non-mediated transport mechanisms? 1. Diffusion 2. Osmosis 3. Filtration Are these active transport or passive transport?

  27. Review 1. Osmosis is best defined as the movement of A) molecules from an area of high concentration to an area of lower concentration B) molecules from an area of low concentration to an area of higher concentration C) water molecules across a membrane from an area of low water concentration to an area of higher concentration D) water molecules across a membrane from an area of high water concentration to an area of lower concentration 2. A red blood cell placed in a hypertonic solution will A) Expand B) Burst C) Shrink D) Have no change in shape 3. Facilitated diffusion requires A) Enzymes C) lipid carriers B) Carrier proteins D) carbohydrate carriers

  28. Review • The main difference between filtration and diffusion is

  29. Active Transport Transport of solute across membrane up (against) concentration gradient Analogous to a pump moving water uphill. ATP Driven Active Transport Energy from adenosine triphosphate (ATP) drives substances across the plasma membrane with the aid of carrier molecules. Examples: Sodium-potassium pump, bring amino acids into cell, pump Ca2+ out of cell Diagram: Cell, College of DuPage

  30. Sodium-Potassium Pump • Needed because Na+ and K+ constantly leak out of the cell • One ATP utilized to exchange three Na+ pushed out for two K+ brought in to cell

  31. Functions of Na+ K+ Pump • Regulation of cell volume • Heat production (thyroid hormone increases number of pumps; heat a by-product • Maintenance of membrane potential in all cells • Secondary active transport (no ATP used)

  32. Vesicular Transport • Transport large particles or fluid droplets through membrane in vesicles (uses ATP) • Exocytosis • Endocytosis • Phagocytosis • Pinocytosis • Receptor mediated endocytosis

  33. Phagocytosis = Cell Eating

  34. Pinocytosis= Cell Drinking Taking in droplets of ECF • Occurs in all human cells Membrane caves in, then pinches off into the cytoplasm as pinocytotic vesicle

  35. Transcytosis • Transport of a substance across a cell • Capture on one side and release on the other side • Receptor mediated endocytosis moves it into cell and exocytosis moves it out the other side

  36. Receptor Mediated Endocytosis

  37. Exocytosis

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