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Cell Membrane and Transport (PowerPoint)

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Cell Membrane and Transport (PowerPoint) Powered By Docstoc
					  What is an Isotonic Solution?
• [Water] inside cell =
  [Water] outside cell

• Cell is at equilibrium
   – Molecules are equally
                             95%
     distributed in end      water
• The amount of water
  entering the cell = the            95%
                                     water
  amount of water
  leaving the cell
 What is a hypotonic solution?
• A solution that has
  MORE water, and
  LESS solute

• The cell can lyse or   100%
                         water
  burst if left in a
  hypotonic solution
                                 95%
                                 water
 What is a hypertonic solution?
• A solution that has
  LESS water and MORE
  solute

• The cell will dehydrate
                            90%
                            water
                                    95%
                                    water
 Which direction does water flow?
a) Water doesn’t flow at all.
b) Water flows from an area of low
   concentration to an area of high
   concentration.
c) Water flows from an area of high
   concentration to an area of low
   concentration.
                   Lipids
• Lipids function in:
  – Energy (E) storage,
  – forming cell membranes,
  – and as chemical messengers
    (e.g., hormones)
• Nonpolar (hydrophobic)
• Made up mostly of Carbon and Hydrogen
  (with a few Oxygen)
                  Lipids
1. Fats (Triglycerides)
  – Glycerol + 3 Fatty Acids
  – Saturated = No Double Bonds (solid)
  – Unsaturated = Double Bonds (liquid)

    OH
         OH




    OH
         OH    Ester Bonds


    OH
         OH
Organic Compounds: Lipids: Phospholipids


                                Lipids
   2. Phospholipids
       – Glycerol with Phosphate Head +
         2 Fatty Acid Chains
       – Amphiphilic (“Both” “lover”)
           •   Hydrophilic headPhosphate
           •   Hydrophobic tail
                              Glycerol
       – Forms 2 layers in water
       – Makes up cell membranes
                             Fatty Acids
                 Egg lab
• Dissolve egg shells
• Rinse
• Calculate initial mass
The plasma/cell membrane is selectively
              permeable
 ~only certain substances are allowed to
             pass through
   What can and can not pass
    through the membrane?
CAN PASS THROUGH    CAN NOT PASS THROUGH
• Things that can   1. Things that can dissolve in
  dissolve in fat      water
• Small molecules   2. Large molecules
• Water             3. Ions: Molecules with plus
                       (+) or minus (-) charges
                              CH2OH




                                  OH
            There are three types…




               No energy is used
     [High]  [Low] (it’s the natural flow)
This means it goes down a concentration gradient
   3 types of Passive Transport

1. Diffusion
2. Osmosis
3. Facilitated Diffusion
Diffusion

[High]  [Low]
Osmosis
               +                           CH2OH

                   Facilitated Diffusion
                                              OH




Passive Transport: Facilitated Diffusion
     There are three types…




        Energy is used
        [Low]  [High]
This means it goes up or against a
     concentration gradient
       3 Examples of Active
            Transport
1. Protein pumps
2. Endocytosis
3. Exocytosis
            Protein Pumps
Protein Pumps: proteins use energy to pull or
    pump materials into or out of the cell to
    stockpile or store substances the cell needs
                     Endocytosis
•   When cells engulf particles into the cell
•   2 types
    1. Phagocytosis: When a cell wraps part of its
       membrane around
       a large particle
       forming a “pocket”
       or vesicle
    2. Pinocytosis: The
       same process,
       but with smaller
       particles or liquids
                 Exocytosis
1. A vesicle carrying a
   substance
2. fuses with the cell
   membrane
3. and releases the
   substance