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Biology chapter 3

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Transcript of "Biology chapter 3"

  1. 1. MOVEMENT OF SUBSTANCE ACROSS THE PLASMA MEMBRANE Chapter 3 O2 CO2 CO2 O2
  2. 2. Movement of substance across plasma membrane  Living cell carrying out life process: a) Absorb water and nutrient b) Excrete waste product c) Exchange respiratory waste product  These process IMPORTANT because : a) Maintain optimal pH value b) Obtain nutrient for metabolism c) Eliminate toxic waste product d) Secrete useful substance like hormone and enzyme  Movement substance in and out via PLASMA MEMBRANE ~regulate exchange between content of cell and external envi.
  3. 3. STRUCTURE OF PLASMA MEMBRANE
  4. 4. PLASMA MEMBRANE…  Was proposed by S.J Singer and G. Nicolson (1972) ~FLUID MOSAIC MODEL  Based on this model, structure of plasma membrane compose of phospholipids bilayer and various type of protein molecule
  5. 5.  A phospholipids is AMPHIPATHIC MOLECULE~ has both hydrophilic region and hydrophobic region  Polar head is HYDROPHILIC (attracted to water) while non-polar tail is HYDROPHOBIC (repelled by water)  The interaction ~~prevent adjacent phospholipids from packing too tightly ~more fluid  Cholesterol ~stabilize and strength the plasma membrane, more flexible
  6. 6. PLASMA MEMBRANE  According to this model:  Phospholipids, protein and other component of membrane are not rigid or static, but form a dynamic and fluid structure  Protein molecule embedded in phospholipis bilayer float freely  Protein and phospholipids free to move sideways within membrane~~FLUID CHARACTERISTIC  Various protein built into plasma membrane~form MOSAIC PATTERN
  7. 7. THE PERMEABILITY OF PLASMA MEMBRANE  Plasma membrane ~PARTIALLY PERMEABLE @ SEMI-PERMEABLE~ certain substance can move freely while other cannot  Membrane envelope organelles and allow certain substance enter or leave the organelles Eg: Visking tube, cellophane tape, egg membrane  Selective permeability depend on~~Size and polarity a) Small & neutral (H2O, O2, CO2), Lipid soluble ~~easily across b) big & polar (glucose, amino acid), charge ion ~~cannot cross and need help of TRANSPORT
  8. 8. MOVEMENT OF SUBSTANCE ACROSS PLASMA MEMBRANE Passive transport •Movement of substance from concentration to concentration •Move DOWN their concentration gradient •NOT required energy Simple diffusion Osmosis Facilitated diffusion Active transport •Movement of substance from concentration to concentration •Move AGAINTS their concentration gradient •Required energy
  9. 9.  In liquid and gases  Molecule diffuse DOWN concentrated gradient via plasma membrane until EQUILIBRIUM is reach  At eq. molecule continue move back and forth, but no net change to both side  Soluble are small uncharged & molecule dissolve in fats (vit A, D, E, and K)  The bigger concentration gradient, the faster PASSIVE TRANSPORT 1) Simple diffusion
  10. 10. PASSIVE TRANSPORT 2) osmosis  Passive transport in WATER  Diffusion of water (solvent) DOWN concentration gradient via semi permeable membrane  Water move from higher [water] ~dilute~ to a region of lower [water] ~concentrated~ until concentration of both side are same. Then water molecule move at a same rate in both direction  Eg : absorption of water by root hair of a
  11. 11. Comparison between simple diffusion and osmosis Similarities •Not require energy. Kinetic energy molecule/ion that make them move randomly •Move DOWN concentration gradient •Move high concentration region to low concentration gradient until reach equilibrium Differences SIMPLE DIFFUSION CRITERIA OSMOSIS Gaseous and water Molecule Water Not required semi permeable Membrane Required semi permeable
  12. 12.  Some substance cannot cross plasma membrane via simple diffusion ~ need help of transport protein  Move DOWN concentration gradient  Rate depend on number of transport protein how fast it move  The solute transported by carrier protein & protein pore  Protein pore small charge (ion) via pore in protein  Carrier protein uncharged polar~~ can change shape and each carrier move specific substance PASSIVE TRANSPORT 3) facilitated diffusion
  13. 13.  Movement of substance across plasma membrane from a region of LOW concentration to region of HIGH concentration (AGAINTS concentration gradient)  Require work to transport against concentration so need energy ~ATP  Perform by specific protein molecule ~~need energy to change the shape ~~to pump or transport  EG : intake of mineral ions by root hair of plant ACTIVE TRANSPORT
  14. 14. Active transport of sodium ions (Na+)
  15. 15. Comparison between passive transport and active transport Please make a mind mapping the movement of substance across the plasma membrane
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