P.mauri membrane transport


Published on

Published in: Education, Technology
  • Be the first to comment

No Downloads
Total Views
On Slideshare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

P.mauri membrane transport

  1. 1. Cell Membrane and Transport Prof. Patrizia Mauri Liceo Rodari – Prato - Italy
  2. 2. About Cell Membrane <ul><li>All cells have a cell membrane. Functions: </li></ul><ul><li>It p rovides the envelope for the cell and separates cytoplasm from the outer environment </li></ul><ul><li>It controls what enters and exits the cell to maintain an internal balance called homeostasis </li></ul>
  3. 3. Cell Membranes from Opposing Neurons } cell membrane 7nm wide Cell membrane { Nerve cell Nerve cell Gap between cells
  4. 4. <ul><li>Lipid Bilayer -2 layers of phospholipids </li></ul><ul><ul><li>Phosphate head is polar (water loving) </li></ul></ul><ul><ul><li>Fatty acid tails non-polar (water fearing) </li></ul></ul><ul><ul><li>Proteins embedded in membrane </li></ul></ul>Cell Membranes Structure Phospholipid Lipid Bilayer
  5. 7. Proteins Membrane movement animation Polar heads love water & dissolve. Non-polar tails hide from water . Carbohydrate cell markers Fluid Mosaic Model of the cell membrane
  6. 8. <ul><li>Cell membrane has pores (tunnels) </li></ul><ul><li>Each pore is selectively permeable: it allows some molecules to get in and keeps other molecules out </li></ul><ul><li>The structure helps the membrane to be selective! </li></ul>About Cell Membrane
  7. 9. Outside of cell Inside of cell (cytoplasm ) Lipid Bilayer Proteins Transport Protein Phospholipids Carbohydrate chains Structure of the Cell Membrane Go to Section: Animations of membrane structure
  8. 10. Types of Cellular Transport <ul><li>Passive Transport </li></ul><ul><li>cell doesn’t use energy </li></ul><ul><ul><li>Diffusion </li></ul></ul><ul><ul><li>Facilitated Diffusion </li></ul></ul><ul><ul><li>Osmosis </li></ul></ul><ul><li>Active Transport </li></ul><ul><li>cell does use energy </li></ul><ul><ul><li>Protein Pumps </li></ul></ul><ul><ul><li>Endocytosis </li></ul></ul><ul><ul><li>Exocytosis </li></ul></ul>high low This is gonna be hard work!! high low Weeee!!!
  9. 11. Types of Passive Transport <ul><li>Diffusion </li></ul><ul><li>Facilitated Diffusion – diffusion with the help of transport proteins </li></ul><ul><li>Osmosis – diffusion of water </li></ul>
  10. 12. Diffusion <ul><li>Cell uses no energy </li></ul><ul><li>Molecules move randomly </li></ul><ul><li>Molecules spread out from an area of high concentration to an area of l ow concentration . </li></ul><ul><li>(High ------> Low) </li></ul>
  11. 13. Diffusion <ul><li>Diffusion : random movement of particles from an area of high concentration to an area of low concentration . </li></ul><ul><li>( High to Low ) </li></ul><ul><li>Diffusion continues until all molecules are evenly distributed ( equilibrium is reached)- </li></ul><ul><li>Note: molecules will then still move around but stay spread out. </li></ul>http://bio.winona.edu/berg/Free.htm Simple Diffusion Animation
  12. 14. <ul><li>We can have free diffusion only in gaseous or liquid systems. </li></ul><ul><li>To cross the cell membrane through diffusion, molecules have to be NON- POLAR and SMALL (O 2 - CO 2 ). </li></ul><ul><li>H 2 O, Glucose, Aminoacids, Ions cannot cross the plasma membrane because they are POLAR. </li></ul>
  13. 15. So ....... how can you describe : 1. The O 2 flow in a breathing cell? 2. The CO 2 f low in a breathing cell? 3. The O 2 flow in a photosynthesizing cell? 4. The CO 2 flow in a photosynthesizing cell?
  14. 16. <ul><li>Facilitated diffusion : diffusion of specific particles through transport proteins located in the membrane </li></ul><ul><li>Transport Proteins are specific – they “select” only certain molecules to cross the membrane </li></ul>Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer ) Facilitated Diffusion Carrier Protein A B
  15. 17. High Concentration Low Concentration Cell Membrane Glucose molecules Protein channel Passive Transport: Facilitated Diffusion Go to Section: Transport Protein Through Cellular Transport High Low <ul><li>Channel Proteins animations </li></ul>
  16. 18. <ul><li>Osmosis : diffusion of water through a selectively permeable membrane </li></ul><ul><li>Water moves from high to low concentrations </li></ul><ul><li>Water moves freely through pores. </li></ul><ul><li>Solute (green) to large to move across. </li></ul>Osmosis animation Osmosis
  17. 19. Now we are going to analyze the effects of osmosis on cells and organisms .........
  18. 20. We can have three different types of solution outside the cell: Hypotonic = at lower concentration Hypertonic = at higher concentration Isotonic = at the same concentration
  19. 21. Hypotonic Solution Hypotonic : The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result : Water moves from the solution to inside the cell: the cell swells and bursts open (Cytolysis)! <ul><li>Osmosis Animations for isotonic, hypertonic, and hypotonic solutions </li></ul>
  20. 22. Hypertonic Solution Hypertonic : The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) Result : Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)! <ul><li>Osmosis Animations for isotonic, hypertonic, and hypotonic solutions </li></ul>shrinks
  21. 23. Isotonic Solution Isotonic : The concentration of solutes in the solution is equal to the concentration of solutes inside the cell . Result : Water moves equally in both directions and the cell remains of the same size! (Dynamic Equilibrium) <ul><li>Osmosis Animations for isotonic, hypertonic, and hypotonic solutions </li></ul>
  22. 24. What type of solutions are these? A C B Hypertonic Isotonic Hypotonic
  23. 25. How Organisms Deal with Osmotic Pressure <ul><li>Paramecium ( protist ) removing excess water video </li></ul><ul><li>Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called turgor pressure . </li></ul><ul><li>A protist like Paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding. </li></ul><ul><li>Animal cells are bathed in blood and intercellular liquid. Kidneys keep the blood isotonic by removing excess salt and/or water. </li></ul>
  24. 26. Active Transport <ul><li>The cell uses energy </li></ul><ul><li>It actively transports molecules where they are needed </li></ul><ul><li>The movement is from an area at low concentration to an area at high concentration </li></ul><ul><li>Low ----> High </li></ul>
  25. 27. Types of Active Transport <ul><li>Protein Pumps - are transport proteins that require energy to do work. </li></ul><ul><li>Symport </li></ul><ul><li>Antiport </li></ul><ul><li>Example: Sodium/Potassium Pump </li></ul>Sodium Potassium Pumps (Active Transport using proteins) Protein changes shape to move molecules: this requires energy ! ‪http :// medicinapertutti.altervista.org /argomento/ pompa-sodio-potassio
  26. 28. Types of Active Transport <ul><li>Endocytosis : taking bulky material into a cell </li></ul><ul><li>Uses energy </li></ul><ul><li>Cell membrane in-folds around food particle </li></ul><ul><li>“ cell eating ” </li></ul><ul><li>Forms food vacuole & digests food </li></ul><ul><li>This is how white blood cells eat bacteria! </li></ul>
  27. 29. Types of Active Transport <ul><li>Exocytosis : f orces material out of cell in bulk </li></ul><ul><li>Membrane surrounding the material fuses with cell membrane </li></ul><ul><li>Cell changes shape – requires energy </li></ul><ul><li>EX: Hormones or wastes released from cell </li></ul>Endocytosis & Exocytosis animations
  28. 30. <ul><li>Animations of Active Transport & Passive Transport </li></ul>