Plasma Membrane

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					Plasma Membrane
Plasma Membrane
Structure

  Phospholipid bi-layer
Structure

 Phosphate Head – Hydrophilic

 Lipid Tail – Hydrophobic

 Glycoprotein/Glycolipids – Cell markers

 Carrier Protein – Passive and Active
Structure
                     Carbohydrate cell
                     markers




 Proteins           Phospholipid molecules




  Floating Mosaic
Function of the Plasma
Membrane
  - selectively permeable membrane
  - allows for communication between cells
  - provides the cell with a specific “marker”
Plasma Membrane

  http://telstar.ote.cmu.edu/Hughes/tutorial/
   cellmembranes/bil.swf

  Construction of the Cell Membrane -
   Learning Ac - Flash Player Installation
Carrier Protein

  Passive Channel – Leakage channel

  Active Channel – Open and close to let
   larger molecules through
                 - Uses Cellular energy
                     (ATP)
  Channel Protein
Particle Theory

  1. All matter is made of particles

  2. The particles are in constant motion
   (Kinetic motion of particles)

  3. The closer the particles are together,
   the greater the attractiveness between
   them.
Particle Theory

  Solids – definite shape and volume

  Liquids – definite volume but indefinite
   shape

  Gases – indefinite shape and volume
  Matter
Cellular Transport

  Passive Transport – use no cellular
   energy
  A) Diffusion
  B) Osmosis
  C) Facilitated Diffusion
A. Diffusion
  - Movement of particles from an area of
   High concentration to an area of Low
   concentration
  - Particles will move until they are evenly
   distributed in an Equilibrium
  - Particles continue random movement,
   but it has no affect on the equilibrium
  Diffusion
B. Osmosis

  - special diffusion where water passes
   through a selectively permeable
   membrane from an area of High
   concentration to an area of Low
   concentration
  Osmosis
  Osmosis II
C. Facilitated Diffusion

  - special diffusion that is made faster by
   using Passive Channels (leakage
   channels)
  - can result in a conformational change in
   the shape of the protein.
  Facilitative Diffusion
  Facilitated Diffusion II
  Facilitated Diffusion III
Try these:
  1. The plasma membrane consists of ___ layers.
  2. The molecules that make up the plasma membrane
   are called ______
  3. The phosphate heads like water and are called
   ______.
  4. The lipid tails don’t like water and are called ______.
  5. Special protein molecules called _____ are found
   throughout the plasma membrane.
  6. Cell markers called _______ are attached to the top
   of these protein molecules.
  7. The Particle Theory states that all matter is made up
   of tiny particles and that they are in _________.
  8. Cells need to move materials in and out to maintain
   a state of balance between what is inside and outside.
   This balance is called _______
 9. Cells move materials in and out in 2 ways.
  ___________ and ___________
 10. ________transport doesn’t require the cell to
  expend any energy.
 11. ________ transport requires the cell to use some of
  it’s own energy stored in _____
 12. There are 3 types of Passive Transport ________,
  _________ and __________.
 13. Movement of any particles from H to L is called
  ________.
 14. Movement of water molecules from H to L is called
  ________.
 15. Diffusion of particles that are helped by carrier
  protein is called __________.
Review of Passive
Transport
  Passive Transport
Environments that Cells
might find themselves in:
  A) Hypotonic Solutions – greater concentration
   of water OUTSIDE the cell

  B) Hypertonic Solutions – greater
   concentration of water INSIDE the cell

  C) Isotonic Solutions – even concentrations of
   water inside and outside the cell
How will cells react in
each??
  Animal cells

  Hypotonic Solution
  - water moves into the cell (osmosis), the
   cell swells, and may burst (Cytolysis)

  Hypotonic Solution
How will cells react in
each?
  Animal cells

  Hypertonic – water moves from inside
   out and the cell shrivels and dehydrates

  Hypertonic
How will cells react in
each?
  Animal cells

  Isotonic – water moves in and out of the
   cell at the same rate (Random movement)

  Isotonic
Another look:

 




          Solutions
What about plant cells?

  Hypotonic – water moves in and Turgor
   Pressure in the cell increases.
What about plant cells?

  Hypertonic – water moves out of the cell
   and turgor pressure drops
             - the plasma membrane pulls
   away from the cell wall and the cell wilts.
  Plasmolysis
What about plant cells?

  Isotonic – water moves in and out at the
   same rate.
Another look:
Cellular Traffic

  Active Transport (uses ATP)
    A) Endocytosis
    B) Exocytosis
    C) Movement against the “concentration
     gradient”.
Cellular Traffic
  A) Endocytosis – movement of large particles
   into a cell packaged in vesicles . The cell uses
   energy stored in ATP

  i) Phagocytosis -

  - cell engulfs a large food particle by wrapping
   it’s cytoplasmic arms around the particle
  Phagocytosis
Cellular Traffic

  i) Pinocytosis – cell engulfs a smaller
   particle or water droplet into the cell by
   indenting the plasma membrane. The cell
   uses energy stored in ATP
  Pinocytosis
  Pinocytosis 2
Cellular Traffic

  B) Exocytosis – excreting materials from
   a cell packaged in vesicles. The cell uses
   energy stored in ATP.

  Exocytosis
  Exocytosis 2
Cellular Traffic

  C) Movement against the Concentration
   Gradient (L to H)
  Particles are drawn against the concentration
   gradient using active channels that open and
   close using cellular energy

  L to H
  L-H
Cellular Transport Review

  Thirst Reflex

  Passive Transport

  Environments

  Drag and Drop Cell membrane
         Homeostasis

 All these examples of cellular traffic are
  designed to help the cell maintain a state
  of balance between the inside and the
  outside of the cell.

				
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