Chapter 5: Cell Transport: Membrane Structure and Function
Chapter Objectives <ul><li>Describe the fluid mosaic model of membrane structure and explain the underlying reasons for th...
Chapter  – Key Vocabulary <ul><li>Selectively permeable </li></ul><ul><li>Phospholipid </li></ul><ul><li>Hydrophobic </li>...
 
 
 
<ul><li>Membranes organize the chemical activities of cells. </li></ul><ul><ul><li>They separate cells from their outside ...
<ul><li>Membrane phospholipids form a bilayer. </li></ul><ul><li>Phospholipids   are: </li></ul><ul><ul><li>fats with two ...
<ul><li>The membrane is a  Fluid Mosaic  of phospholipids and proteins.  WHY? </li></ul><ul><ul><li>There are proteins emb...
Fluid-mosaic model of plasma membrane structure Slide number: 1 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 2 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 3 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 4 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 5 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 6 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 7 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 8 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 9 Copyright © The McGraw-Hill Companies, Inc. Permission req...
Fluid-mosaic model of plasma membrane structure Slide number: 10 Copyright © The McGraw-Hill Companies, Inc. Permission re...
Functions of Membrane Proteins <ul><li>Channel – moves materials </li></ul><ul><li>Carrier – combines with a substance to ...
Chart from Textbook  Fig. 4.2
Transport through cell membranes <ul><li>The phospholipid bilayer is a good barrier around cells, especially to water solu...
Fig. 4.3
Passage Through The Phospholipid Bilayer <ul><li>What molecules can pass through the phospholipids bilayer? </li></ul><ul>...
Diffusion of liquids
Fig. 4.4
Fig. 4.4.a
Fig. 4.4.b
Fig. 4.4.c
Diffusion through a membrane Cell membrane Inside cell Outside cell
Diffusion through a membrane Cell membrane Inside cell Outside cell diffusion
Diffusion through a membrane Cell membrane Inside cell Outside cell EQUILIBRIUM
Simple Diffusion <ul><li>Diffusion is the  net movement  of molecules (or ions) from a region of their high concentration ...
REMEMBER….. <ul><li>DIFFUSION refers to the movement (or non) of the SOLUTE (glucose, starch, gases across the membrane! <...
Molecules that diffuse through cell membranes!
Osmosis
Osmosis <ul><li>‘ The  diffusion  of water from an area of high concentration of water molecules to an area of low concent...
Osmosis Cell membrane partially permeable. Inside cell Outside cell VERY High conc. of water molecules.  VERY Low conc. of...
Osmosis Cell membrane partially permeable. Inside cell Outside cell High conc. of water molecules. Lower  water potential....
Osmosis Cell membrane partially permeable. Inside cell Outside cell OSMOSIS EQUILIBRIUM. Equal water concentration on each...
 
<ul><li>Tonicity </li></ul><ul><li>Movement of  water  in response to the amount of solute on either side of a membrane. <...
Tonicity <ul><li>Tonicity comes  -in 3 types: </li></ul><ul><li>Hypertonic – the side the membrane or part of the solution...
? ? Which side is hypotonic and which side is hypertonic? A B Draw THIS  U-TUBE as it will appear after osmosis takes place.
Which way  will the water move?
WHY?
 
<ul><li>A solution is made of a solute and solvent. </li></ul><ul><ul><li>OSMOSIS:  solvent  is WATER. </li></ul></ul><ul>...
<ul><li>Remember: A hypertonic solution is always relative to a hypotonic solution  </li></ul>
TONICITY IN CELLS <ul><li>Osmosis  </li></ul>
Water Movement in the Cell <ul><li>This is an Osmosis tutorial…for the smart board…. </li></ul><ul><li>osmosis#Osmosis#Osm...
 
 
 
 
Hypotonic vs. Hypertonic Cells placed in a: <ul><li>Hypotonic </li></ul><ul><li>animal cell will gain water – LYSE </li></...
Do Water Molecules Stop Moving in Isotonic Conditions ? <ul><li>No. </li></ul><ul><li>They continue to diffuse, however th...
Facilitated Diffusion <ul><li>Large polar molecules such as  glucose  and  amino acids , cannot diffuse across the phospho...
Facilitated Diffusion Animation
Facilitated Diffusion through a membrane Cell membrane Inside cell Outside cell Protein channel
Facilitated Diffusion through a membrane Cell membrane Inside cell Outside cell Protein channel diffusion
Facilitated Diffusion through a membrane Cell membrane Inside cell Outside cell Protein channel diffusion EQUILIBRIUM
Facilitated Diffusion: Molecules will randomly move through the opening like pore, by diffusion.  This requires no energy,...
Active Transport
<ul><li>Cells expend energy for  active transport . </li></ul><ul><ul><li>Active transport  involves the aid of a transpor...
 
 
<ul><li>Exocytosis  and  Endocytosis  transport large molecules. </li></ul><ul><ul><li>In  exocytosis , membrane-bound  ve...
Exocytosis
<ul><ul><li>In  endocytosis , the plasma membrane surrounds materials outside the cell, closes around the materials, and f...
a) Phagocytosis <ul><li>The “engulfing” of material by the cell </li></ul>
b) Pinocytosis <ul><li>The “cell drinking” of material by the cell </li></ul>Phagocytosis takes in solid particles. Pinocy...
<ul><li>Active transport is used to: </li></ul><ul><li>Generate charge gradients. Ex. In the mitochondrion, hydrogen ion p...
Review of passive and active transport: ?
Review of passive and active transport: ?
Review of passive and active transport: ?
Review of passive and active transport: ?
Review of passive and active transport:
 
 
 
 
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Membrane structure and function master 2011

  1. 1. Chapter 5: Cell Transport: Membrane Structure and Function
  2. 2. Chapter Objectives <ul><li>Describe the fluid mosaic model of membrane structure and explain the underlying reasons for this structure. </li></ul><ul><li>Outline the roles of phospholipids, cholesterol, glycolipids, proteins and glycoproteins in membranes. </li></ul><ul><li>Outline the roles of the plasma membrane, and the roles of membranes within cells. </li></ul><ul><li>Describe and explain how molecules can get in and out of cells (cross cell membranes) by the processes of diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis. </li></ul><ul><li>Describe the effects on animal and plant cells of immersion in solutions of different “water potential”. </li></ul>
  3. 3. Chapter – Key Vocabulary <ul><li>Selectively permeable </li></ul><ul><li>Phospholipid </li></ul><ul><li>Hydrophobic </li></ul><ul><li>Hydrophilic </li></ul><ul><li>Passive Transport </li></ul><ul><li>Active Transport </li></ul><ul><li>Diffusion </li></ul><ul><li>Osmosis </li></ul><ul><li>Concentration Gradient </li></ul><ul><li>Hypertonic </li></ul><ul><li>Hypotonic </li></ul><ul><li>Isotonic </li></ul><ul><li>Turgor </li></ul><ul><li>Plasmolysis </li></ul><ul><li>Facilitated diffusion </li></ul><ul><li>Exocytosis </li></ul><ul><li>Endocytosis </li></ul><ul><li>Phagocytosis </li></ul><ul><li>Pinocytosis </li></ul><ul><li>Fluid Mosaic Model </li></ul><ul><li>Equilibrium </li></ul>
  4. 7. <ul><li>Membranes organize the chemical activities of cells. </li></ul><ul><ul><li>They separate cells from their outside environments. </li></ul></ul><ul><ul><li>They control the passage of molecules from one side of the membrane to the other. </li></ul></ul><ul><ul><li>Membranes are selectively permeable ; that is, they allow some substances to cross more easily than others and blocks passage of some substances altogether. </li></ul></ul>
  5. 8. <ul><li>Membrane phospholipids form a bilayer. </li></ul><ul><li>Phospholipids are: </li></ul><ul><ul><li>fats with two nonpolar fatty acid “tails” </li></ul></ul><ul><ul><li>one polar phosphate “head” </li></ul></ul><ul><ul><li>attached to glycerol. </li></ul></ul><ul><li>In water , thousands of individual molecules form a “stable bilayer”, aiming their heads out and their tails in. </li></ul><ul><li>The hydrophobic interior of this bilayer offers an effective barrier to the flow of most hydrophilic molecules. </li></ul>
  6. 9. <ul><li>The membrane is a Fluid Mosaic of phospholipids and proteins. WHY? </li></ul><ul><ul><li>There are proteins embedded in the lipid bilayer. </li></ul></ul><ul><ul><ul><ul><li>Attached to the outer surface: Peripheral Protein </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Running through the whole membrane: Integral Protein </li></ul></ul></ul></ul><ul><ul><li>The cell membrane appears to show some fluidity…lipids and proteins moving sideways in response to functions and surrounding conditions. </li></ul></ul><ul><ul><li>Cholesterol helps stabilize the fluidity at different temperatures. </li></ul></ul>
  7. 10. Fluid-mosaic model of plasma membrane structure Slide number: 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain phospholipid bilayer integral protein cholesterol peripheral protein filaments of the cytoskeleton hydro- phobic tails hydrophilc heads hydrophilc heads
  8. 11. Fluid-mosaic model of plasma membrane structure Slide number: 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycoprotein carbohydrate (sugar) chain
  9. 12. Fluid-mosaic model of plasma membrane structure Slide number: 3 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain
  10. 13. Fluid-mosaic model of plasma membrane structure Slide number: 4 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain integral protein
  11. 14. Fluid-mosaic model of plasma membrane structure Slide number: 5 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain integral protein cholesterol
  12. 15. Fluid-mosaic model of plasma membrane structure Slide number: 6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain integral protein cholesterol peripheral protein
  13. 16. Fluid-mosaic model of plasma membrane structure Slide number: 7 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain integral protein cholesterol peripheral protein filaments of the cytoskeleton
  14. 17. Fluid-mosaic model of plasma membrane structure Slide number: 8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain phospholipid bilayer integral protein cholesterol peripheral protein filaments of the cytoskeleton
  15. 18. Fluid-mosaic model of plasma membrane structure Slide number: 9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain phospholipid bilayer integral protein cholesterol peripheral protein filaments of the cytoskeleton hydro- phobic tails hydrophilc heads hydrophilc heads
  16. 19. Fluid-mosaic model of plasma membrane structure Slide number: 10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inside cell Outside cell glycolipid glycoprotein carbohydrate (sugar) chain phospholipid bilayer integral protein cholesterol peripheral protein filaments of the cytoskeleton hydro- phobic tails hydrophilc heads hydrophilc heads
  17. 20. Functions of Membrane Proteins <ul><li>Channel – moves materials </li></ul><ul><li>Carrier – combines with a substance to move </li></ul><ul><li>Cell Recognition – glycoproteins – helps cells find molecules </li></ul><ul><li>Receptor – specific to a certain molecule </li></ul><ul><li>Enzyme – carries out metabolic functions </li></ul>
  18. 21. Chart from Textbook Fig. 4.2
  19. 22. Transport through cell membranes <ul><li>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. </li></ul><ul><li>There are 5 basic mechanisms: </li></ul><ul><li>Passive Transport </li></ul><ul><li>DIFFUSION </li></ul><ul><li>OSMOSIS </li></ul><ul><li>FACILITATED DIFFUSION </li></ul><ul><li>_______________________________________ </li></ul><ul><li>Active Transport </li></ul><ul><li>4. ENDOCYTOSIS </li></ul><ul><li>5. EXOCYTOSIS </li></ul>
  20. 23. Fig. 4.3
  21. 24. Passage Through The Phospholipid Bilayer <ul><li>What molecules can pass through the phospholipids bilayer? </li></ul><ul><li>Small non polar (O2) </li></ul><ul><li>Large non polar (lipids) </li></ul><ul><li>Small polar (water and CO2) </li></ul><ul><li>What molecules cannot pass freely through the bilayer? </li></ul><ul><li>Large polar (starch, glucose, and proteins) </li></ul><ul><li>Ions (Na+, K+) </li></ul>
  22. 25. Diffusion of liquids
  23. 26. Fig. 4.4
  24. 27. Fig. 4.4.a
  25. 28. Fig. 4.4.b
  26. 29. Fig. 4.4.c
  27. 30. Diffusion through a membrane Cell membrane Inside cell Outside cell
  28. 31. Diffusion through a membrane Cell membrane Inside cell Outside cell diffusion
  29. 32. Diffusion through a membrane Cell membrane Inside cell Outside cell EQUILIBRIUM
  30. 33. Simple Diffusion <ul><li>Diffusion is the net movement of molecules (or ions) from a region of their high concentration to a region of their lower concentration. </li></ul><ul><li>molecules move down a concentration gradient . </li></ul><ul><li>Molecules have kinetic energy , which makes them move about randomly. </li></ul><ul><li>As a result of diffusion, molecules reach an equilibrium where they are evenly spread out. </li></ul><ul><li>Equilibrium = no net movement of molecules from either side. </li></ul>
  31. 34. REMEMBER….. <ul><li>DIFFUSION refers to the movement (or non) of the SOLUTE (glucose, starch, gases across the membrane! </li></ul>
  32. 35. Molecules that diffuse through cell membranes!
  33. 36. Osmosis
  34. 37. Osmosis <ul><li>‘ The diffusion of water from an area of high concentration of water molecules to an area of low concentration of water across a semi permeable membrane. </li></ul>
  35. 38. Osmosis Cell membrane partially permeable. Inside cell Outside cell VERY High conc. of water molecules. VERY Low conc. of water molecules. Sugar molecule DILUTE SOLUTION CONCENTRATED SOLUTION
  36. 39. Osmosis Cell membrane partially permeable. Inside cell Outside cell High conc. of water molecules. Lower water potential. Low conc. of water molecules. High water potential. OSMOSIS
  37. 40. Osmosis Cell membrane partially permeable. Inside cell Outside cell OSMOSIS EQUILIBRIUM. Equal water concentration on each side. Equal water potential has been reached. There is no net movement of water
  38. 42. <ul><li>Tonicity </li></ul><ul><li>Movement of water in response to the amount of solute on either side of a membrane. </li></ul><ul><li>The Rule - </li></ul><ul><li>Water will always move toward the side of the membrane with the most solute! </li></ul>
  39. 43. Tonicity <ul><li>Tonicity comes -in 3 types: </li></ul><ul><li>Hypertonic – the side the membrane or part of the solution with the greater amount of solute </li></ul><ul><li>Hypotonic – side/part with the lower amount of solute </li></ul><ul><li>Isotonic – equal solute content </li></ul>
  40. 44. ? ? Which side is hypotonic and which side is hypertonic? A B Draw THIS U-TUBE as it will appear after osmosis takes place.
  41. 45. Which way will the water move?
  42. 46. WHY?
  43. 48. <ul><li>A solution is made of a solute and solvent. </li></ul><ul><ul><li>OSMOSIS: solvent is WATER. </li></ul></ul><ul><ul><li>Solute is what is dissolved in water. </li></ul></ul><ul><ul><li>THE DIRECTION OF WATER’S CONCENTRATION GRADIENT IS ALWAYS OPPOSITE TO THE DIRECTION OF THE SOLUTE’S CONCENTRATION GRADIENT . </li></ul></ul>LOW SOLUTE CONCENTRATION HIGH SOLUTE CONCENTRATION HYPOTONIC HYPERTONIC HIGH WATER CONCENTRATION LOW WATER CONCENTRATION LOW OSMOTIC POTENTIAL HIGH OSMOTIC POTENTIAL DILUTE CONCENTRATED
  44. 49. <ul><li>Remember: A hypertonic solution is always relative to a hypotonic solution </li></ul>
  45. 50. TONICITY IN CELLS <ul><li>Osmosis </li></ul>
  46. 51. Water Movement in the Cell <ul><li>This is an Osmosis tutorial…for the smart board…. </li></ul><ul><li>osmosis#Osmosis#Osmosis#Osmosis </li></ul>
  47. 56. Hypotonic vs. Hypertonic Cells placed in a: <ul><li>Hypotonic </li></ul><ul><li>animal cell will gain water – LYSE </li></ul><ul><li>Plant cell will swell and become TURGID </li></ul><ul><li>Hypertonic </li></ul><ul><li>animal cell will lose water – shrivel </li></ul><ul><li>Plant will lose water – plant cell membrane will detach from cell wall - plasmolysis </li></ul>
  48. 57. Do Water Molecules Stop Moving in Isotonic Conditions ? <ul><li>No. </li></ul><ul><li>They continue to diffuse, however there is no net movement. </li></ul><ul><li>Equal does not mean STOP </li></ul>
  49. 58. Facilitated Diffusion <ul><li>Large polar molecules such as glucose and amino acids , cannot diffuse across the phospholipid bilayer. Also ions such as Na + or Cl - cannot pass. </li></ul><ul><li>These molecules pass through protein channels instead. Diffusion through these channels is called FACILITATED DIFFUSION. </li></ul><ul><li>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. </li></ul>
  50. 59. Facilitated Diffusion Animation
  51. 60. Facilitated Diffusion through a membrane Cell membrane Inside cell Outside cell Protein channel
  52. 61. Facilitated Diffusion through a membrane Cell membrane Inside cell Outside cell Protein channel diffusion
  53. 62. Facilitated Diffusion through a membrane Cell membrane Inside cell Outside cell Protein channel diffusion EQUILIBRIUM
  54. 63. Facilitated Diffusion: Molecules will randomly move through the opening like pore, by diffusion. This requires no energy, it is a PASSIVE process . Molecules move from an area of high concentration to an area of low conc.
  55. 64. Active Transport
  56. 65. <ul><li>Cells expend energy for active transport . </li></ul><ul><ul><li>Active transport involves the aid of a transport protein in moving a solute up a concentration gradient (from an area of low concentration to an area of high concentration). </li></ul></ul><ul><ul><li>Energy is required to help the protein to move the solute molecule. </li></ul></ul><ul><ul><li>What molecular form does this energy usually have? </li></ul></ul><ul><ul><ul><ul><li>ATP – usable cellular energy! </li></ul></ul></ul></ul>
  57. 68. <ul><li>Exocytosis and Endocytosis transport large molecules. </li></ul><ul><ul><li>In exocytosis , membrane-bound vesicles (tiny membrane-bounded sacs) containing large molecules fuse with the plasma membrane and release their contents outside the cell. </li></ul></ul>
  58. 69. Exocytosis
  59. 70. <ul><ul><li>In endocytosis , the plasma membrane surrounds materials outside the cell, closes around the materials, and forms membrane-bound vesicles to contain the materials. </li></ul></ul><ul><ul><ul><li>Two important types of endocytosis are </li></ul></ul></ul><ul><ul><ul><ul><li>phagocytosis (“cell eating”) and </li></ul></ul></ul></ul><ul><ul><ul><ul><li>pinocytosis (“cell drinking”). </li></ul></ul></ul></ul>
  60. 71. a) Phagocytosis <ul><li>The “engulfing” of material by the cell </li></ul>
  61. 72. b) Pinocytosis <ul><li>The “cell drinking” of material by the cell </li></ul>Phagocytosis takes in solid particles. Pinocytosis takes in liquids.
  62. 73. <ul><li>Active transport is used to: </li></ul><ul><li>Generate charge gradients. Ex. In the mitochondrion, hydrogen ion pumps, pump hydrogen ions into the “intermembrane” space of the organelle as part of making ATP.  </li></ul><ul><li>2. Concentrate ions , minerals and nutrients inside the cell that are in low concentration outside.  </li></ul><ul><li>3. Move sodium and potassium ions in and out of the cell. VERY important for nerve function. </li></ul>
  63. 74. Review of passive and active transport: ?
  64. 75. Review of passive and active transport: ?
  65. 76. Review of passive and active transport: ?
  66. 77. Review of passive and active transport: ?
  67. 78. Review of passive and active transport:

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