Powerpoint cell membrane transport copy

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Powerpoint cell membrane transport copy

  1. 1. Transport through cell membranes Biology, Cell membranes and Transport 1
  2. 2. Transport through cell membranes The phospholipid bilayer is a good barrier around cells, especially to water soluble molecules. However, for the cell to survive some materials need to be able to enter and leave the cell. Mechanisms:4. DIFFUSION6. OSMOSIS8. ACTIVE TRANSPORT Biology, Cell membranes and Transport 2
  3. 3. DEFINITIONS DIFFUSION: the net movement of molecules from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement. OSMOSIS: the diffusion of water molecules from a region of their higher concentration (dilute solution) to a region of their lower concentration (concentrated solution), through a partially permeable membrane. ACTIVE TRANSPORT: the movement of ions in or out of a cell through the cell membrane, from a region of their lower concentration to a region of their higher concentration against a concentration gradient, using energy released during respiration. Biology, Cell membranes and Transport 3
  4. 4. Diffusion of liquids Biology, Cell membranes and Transport 4
  5. 5. •Diffusion is the net movement of molecules (orions) from a region of their high concentration toa region of their lower concentration.The molecules move down a concentration gradient.Molecules have kinetic energy, which makes themmove about randomly.As a result of diffusion molecules reach anequilibrium where they are evenly spread out.This is when there is no net movement of moleculesfrom either side. AS Biology, Cell membranes and Transport 5
  6. 6. DIFFUSIONDiffusion is a PASSIVE process which means no energy is usedto make the molecules move, they have a natural kinetic energy. AS Biology, Cell membranes and Transport 6
  7. 7. Diffusion of Bromine Biology, Cell membranes and Transport 7
  8. 8. Diffusion of Bromine Biology, Cell membranes and Transport 8
  9. 9. Diffusion through a membrane Cell membrane Inside cell Outside cell Biology, Cell membranes and Transport 9
  10. 10. Diffusion through a membrane Cell membrane diffusion Inside cell Outside cell Biology, Cell membranes and Transport 10
  11. 11. Diffusion through a membrane Cell membrane Inside cell Outside cell EQUILIBRIUM Biology, Cell membranes and Transport 11
  12. 12. AS Biology, Cell membranes and Transport 12
  13. 13. AS Biology, Cell membranes and Transport 13
  14. 14. What determines the rate of diffusion? There 4 factors: The steepness of the concentration gradient. The bigger the difference between the two sides of the membrane the quicker the rate of diffusion. Temperature. Higher temperatures give molecules or ions more kinetic energy. Molecules move around faster, so diffusion is faster. The surface area. The greater the surface area the faster the diffusion can take place. This is because the more molecules or ions can cross the membrane at any moment. The type of molecule or ion diffusing. Large molecules need more energy to get them to move so they tend to diffuse more slowly. Non-polar molecules diffuse more easily than polar molecules because they are soluble in the AS Biology, Cell membranes and non polar phospholipid tails. Transport 14
  15. 15. Molecules that diffuse through cell membranes Oxygen – Non-polar so diffuses very quickly. Carbon dioxide – Polar but very small so diffuses quickly. Water – Polar but also very small so diffuses quickly. Biology, Cell membranes and Transport 15
  16. 16. Osmosis‘The diffusion of water from an area of high concentration of water molecules (high water potential) to an area of low concentration of water (low water potential) across a partially permeable membrane.’ Biology, Cell membranes and Transport 16
  17. 17. Osmosis CONCENTRATED SOLUTION DILUTE SOLUTION Cell membrane partiallySugar molecule permeable. VERY Low conc. of water molecules. Low water potential.VERY High conc. Outside cell Inside cellof watermolecules. Highwater potential. Biology, Cell membranes and Transport 17
  18. 18. Osmosis Cell membrane partially permeable. Low conc. of water molecules. Low water OSMOSIS potential.High conc. of Inside cell Outside cellwater molecules.High waterpotential. Biology, Cell membranes and Transport 18
  19. 19. Osmosis Cell membrane partially permeable. OSMOSIS Inside cell Outside cellEQUILIBRIUM. Equal water concentration on each side.Equal water potential has been reached. There is no net AS Biology, Cell membranes andmovement of water Transport 19
  20. 20. AS Biology, Cell membranes and Transport 20
  21. 21. AS Biology, Cell membranes and Transport 21
  22. 22. OSMOSIS IN ANIMAL CELLS Red blood cells Biology, Cell membranes and Transport 22
  23. 23. OSMOSIS: Slides of red blood cells Biology, Cell membranes and Transport 23
  24. 24. OSMOSIS IN PLANT CELLS AS Biology, Cell membranes and Transport 24
  25. 25. ACTIVE TRANSPORT AS Biology, Cell membranes and Transport 25
  26. 26. Biology, Cell membranes and Transport 26
  27. 27. Biology, Cell membranes and Transport 27
  28. 28. ACTIVE TRANSPORT: Carrier + energy Biology, Cell membranes and Transport 28
  29. 29. Comparison table Biology, Cell membranes and Transport 29
  30. 30. Endocytosis is the case when a molecule causes the cell membrane to bulge inward, forming a vesicle. Phagocytosis is the type of endocytosis where an entire cell is engulfed. Pinocytosis is when theexternal fluid is engulfed. Receptor-mediated endocytosis occurs whenthe material to be transported binds to certain specific molecules in the membrane. Examples include the transport of insulin and cholesterol into animal cells. AS Biology, Cell membranes and Transport 30
  31. 31. Cell Membrane - Function - Endocytosis The cell membrane can also engulf structures that are much too large to fit through thepores in the membrane proteins this process is known as endocytosis. In this process themembrane itself wraps around the particle and pinches off a vesicle inside the cell. In this animation an ameba engulfs a food particle. AS Biology, Cell membranes and Transport 31
  32. 32. ExocytosisThe opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Biology, Cell membranes and Transport 32
  33. 33. AS Biology, Cell membranes and Transport 33
  34. 34. Vesicle-mediated transport Vesicles and vacuoles that fuse with the cell membrane may beutilized to release or transport chemicals out of the cell or to allow them to enter a cell. Exocytosis is the term applied when transport is out of the cell. AS Biology, Cell membranes and Transport 34

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