Transport through cell         membranes          AS Biology, Cell membranes andi                     Transport           ...
Transport through cell                membranes    The phospholipid bilayer is a good barrier around     cells, especiall...
Diffusion of liquids    AS Biology, Cell membranes and               Transport             3
•Diffusion is the net movement of molecules (orions) from a region of their high concentration toa region of their lower c...
DIFFUSIONDiffusion is a PASSIVE process which means no energy is usedto make the molecules move, they have a natural kinet...
Diffusion of Bromine     AS Biology, Cell membranes and                Transport             6
Diffusion of Bromine     AS Biology, Cell membranes and                Transport             7
Diffusion through a membrane                                  Cell membrane  Inside cell                        Outside ce...
Diffusion through a membrane                                  Cell membrane                       diffusion  Inside cell  ...
Diffusion through a membrane                                  Cell membrane  Inside cell                        Outside ce...
AS Biology, Cell membranes and           Transport             11
AS Biology, Cell membranes and           Transport             12
What determines the rate of diffusion?                There 4 factors:1.   The steepness of the concentration gradient. Th...
Molecules that diffuse through cell                membranes1.   Oxygen – Non-polar     so diffuses very     quickly.1.   ...
Facilitated diffusion   Large polar molecules such as    glucose and amino acids, cannot    diffuse across the phospholip...
AS Biology, Cell membranes and           Transport             16
Facilitated Diffusion through a membrane                                        Cell membrane                             ...
Facilitated Diffusion through a membrane                                        Cell membrane                             ...
Facilitated Diffusion through a membrane                                        Cell membrane                             ...
Facilitated Diffusion:Molecules will randomly move through the opening like pore, bydiffusion. This requires no energy, it...
Facilitated diffusion     AS Biology, Cell membranes and                Transport             21
Osmosis‘The diffusion of water from an area of high concentration of water molecules (high water potential) to an area of ...
Osmosis                                                    CONCENTRATED SOLUTION            DILUTE SOLUTION               ...
Osmosis                                                   Cell membrane                                                   ...
Osmosis                               Cell membrane                               partially                               ...
AS Biology, Cell membranes and           Transport             26
AS Biology, Cell membranes and           Transport             27
AS Biology, Cell membranes and           Transport             28
AS Biology, Cell membranes and           Transport             29
AS Biology, Cell membranes and           Transport             30
AS Biology, Cell membranes and           Transport             31
AS Biology, Cell membranes and           Transport             32
AS Biology, Cell membranes and           Transport             33
AS Biology, Cell membranes and           Transport             34
AS Biology, Cell membranes and           Transport             35
AS Biology, Cell membranes and           Transport             36
ExocytosisThe opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released throug...
AS Biology, Cell membranes and           Transport             38
AS Biology, Cell membranes and           Transport             39
Endocytosis is the case when a molecule causes the cell membrane to      bulge inward, forming a vesicle. Phagocytosis is ...
AS Biology, Cell membranes and           Transport             41
AS Biology, Cell membranes and           Transport             42
Cotransport also uses the process of diffusion. In this case a moleculethat is moving naturally into the cell through diff...
Receptor Proteins  These proteins are used in intercellular communication. In thisanimation you can see the a hormone bind...
Cotransport also uses the process of diffusion. In this case a moleculethat is moving naturally into the cell through diff...
These are carrier proteins. They do not extend through the membrane. They bond and drag molecules through the bilipid laye...
Vesicle-mediated transportVesicles and vacuoles that fuse with the cell membrane may be utilized  to release or transport ...
Cell Membrane - Function - Endocytosis The cell membrane can also engulf structures that are much too large to fit through...
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Cell membrane transport

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Cell membrane transport

  1. 1. Transport through cell membranes AS Biology, Cell membranes andi Transport 1s
  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. There are 4 basic mechanisms:1. DIFFUSION and FACILITATED DIFFUSION2. OSMOSIS3. ACTIVE TRANSPORT4. BULK TRANSPORT AS Biology, Cell membranes and Transport 2
  3. 3. Diffusion of liquids AS Biology, Cell membranes and Transport 3
  4. 4. •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 4
  5. 5. 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 5
  6. 6. Diffusion of Bromine AS Biology, Cell membranes and Transport 6
  7. 7. Diffusion of Bromine AS Biology, Cell membranes and Transport 7
  8. 8. Diffusion through a membrane Cell membrane Inside cell Outside cell AS Biology, Cell membranes and Transport 8
  9. 9. Diffusion through a membrane Cell membrane diffusion Inside cell Outside cell AS Biology, Cell membranes and Transport 9
  10. 10. Diffusion through a membrane Cell membrane Inside cell Outside cell EQUILIBRIUM AS Biology, Cell membranes and Transport 10
  11. 11. AS Biology, Cell membranes and Transport 11
  12. 12. AS Biology, Cell membranes and Transport 12
  13. 13. What determines the rate of diffusion? There 4 factors:1. The steepness of the concentration gradient. The bigger the difference between the two sides of the membrane the quicker the rate of diffusion.2. Temperature. Higher temperatures give molecules or ions more kinetic energy. Molecules move around faster, so diffusion is faster.3. 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 one moment.4. 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 13
  14. 14. Molecules that diffuse through cell membranes1. Oxygen – Non-polar so diffuses very quickly.1. Carbon dioxide – Polar but very small so diffuses quickly.2. Water – Polar but also very small so diffuses quickly. AS Biology, Cell membranes and Transport 14
  15. 15. Facilitated diffusion Large polar molecules such as glucose and amino acids, cannot diffuse across the phospholipid bilayer. Also ions such as Na+ or Cl- cannot pass. These molecules pass through protein channels instead. Diffusion through these channels is called FACILITATED DIFFUSION. Movement of molecules is still PASSIVE just like ordinary diffusion, the only difference is, the molecules go through a protein channel instead of passing between the phospholipids. AS Biology, Cell membranes and Transport 15
  16. 16. AS Biology, Cell membranes and Transport 16
  17. 17. Facilitated Diffusion through a membrane Cell membrane Protein channel Inside cell Outside cell AS Biology, Cell membranes and Transport 17
  18. 18. Facilitated Diffusion through a membrane Cell membrane diffusion Protein channel Inside cell Outside cell AS Biology, Cell membranes and Transport 18
  19. 19. Facilitated Diffusion through a membrane Cell membrane diffusion Protein channel Inside cell Outside cell EQUILIBRIUM AS Biology, Cell membranes and Transport 19
  20. 20. Facilitated Diffusion:Molecules will randomly move through the opening like pore, bydiffusion. This requires no energy, it is a PASSIVE process.Molecules move from an area of high concentration to an area oflow conc. AS Biology, Cell membranes and Transport 20
  21. 21. Facilitated diffusion AS Biology, Cell membranes and Transport 21
  22. 22. 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.’ AS Biology, Cell membranes and Transport 22
  23. 23. Osmosis CONCENTRATED SOLUTION DILUTE SOLUTION Cell membrane partiallySugar molecule permeable. VERY Low conc. of water molecules. High water potential.VERY High conc. Outside cell Inside cellof watermolecules. Highwater potential. AS Biology, Cell membranes and Transport 23
  24. 24. Osmosis Cell membrane partially permeable. Low conc. of water molecules. High water OSMOSIS potential.High conc. of Inside cell Outside cellwater molecules.High waterpotential. AS Biology, Cell membranes and Transport 24
  25. 25. 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 25
  26. 26. AS Biology, Cell membranes and Transport 26
  27. 27. AS Biology, Cell membranes and Transport 27
  28. 28. AS Biology, Cell membranes and Transport 28
  29. 29. AS Biology, Cell membranes and Transport 29
  30. 30. AS Biology, Cell membranes and Transport 30
  31. 31. AS Biology, Cell membranes and Transport 31
  32. 32. AS Biology, Cell membranes and Transport 32
  33. 33. AS Biology, Cell membranes and Transport 33
  34. 34. AS Biology, Cell membranes and Transport 34
  35. 35. AS Biology, Cell membranes and Transport 35
  36. 36. AS Biology, Cell membranes and Transport 36
  37. 37. ExocytosisThe opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. AS Biology, Cell membranes and Transport 37
  38. 38. AS Biology, Cell membranes and Transport 38
  39. 39. AS Biology, Cell membranes and Transport 39
  40. 40. 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 40
  41. 41. AS Biology, Cell membranes and Transport 41
  42. 42. AS Biology, Cell membranes and Transport 42
  43. 43. Cotransport also uses the process of diffusion. In this case a moleculethat is moving naturally into the cell through diffusion is used to draganother molecule into the cell. In this example glucose hitches a ride with sodium. AS Biology, Cell membranes and Transport 43
  44. 44. Receptor Proteins These proteins are used in intercellular communication. In thisanimation you can see the a hormone binding to the receptor. Thiscauses the receptor protein release a signal to perform some action. AS Biology, Cell membranes and Transport 44
  45. 45. Cotransport also uses the process of diffusion. In this case a moleculethat is moving naturally into the cell through diffusion is used to draganother molecule into the cell. In this example glucose hitches a ride with sodium. AS Biology, Cell membranes and Transport 45
  46. 46. These are carrier proteins. They do not extend through the membrane. They bond and drag molecules through the bilipid layer and release them on the opposite side. AS Biology, Cell membranes and Transport 46
  47. 47. Vesicle-mediated transportVesicles and vacuoles that fuse with the cell membrane may be utilized to release or transport chemicals out of the cell or to allow them toenter a cell. Exocytosis is the term applied when transport is out of the cell. AS Biology, Cell membranes and Transport 47
  48. 48. 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 48

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