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The Plasma Membrane -

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Aim: How cell membrane organized? HW #10 1. Complete the handout on the cell Do now: You have 5 min. Explain how the following structures: Nucleolus – PowerPoint PPT presentation

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Title: The Plasma Membrane -


1
Aim How cell membrane organized?
HW 10 1. Complete the handout on the cell
  • Do now You have 5 min.
  • Explain how the following structures
  • Nucleolus
  • Ribosomes
  • Endoplasmic reticulum
  • cytoplasm

2
The Plasma Membrane

3
Photograph of a Cell Membrane

4
I. Cell Membrane A. General
  • 1. Flexible and allows a unicellular organism to
    move

5
B. Function
  • Maintain a high concentration of materials
  • in the cell.

2. Keep harmful materials out.
3. Control the movement of materials into
and out of the cell.
4. Let the cell sense its environment.
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5. Protective barrier 6. Regulate transport in
out of cell (selectively permeable) 7. Allow
cell recognition 8. Provide anchoring sites for
filaments of cytoskeleton
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Membrane Components
8
Proteins Are Critical to Membrane Function
9
  • 9. Provide a binding site for enzymes
  • 10. Interlocking surfaces bind cells together
  • 11. Contains the cytoplasm (fluid in cell)

10
C. Maintains homeostasis
  • Balanced internal condition of cells.
  • Also called equilibrium
  • Maintained by plasma membrane controlling what
    enters leaves the cell.

11
  • Review
  • Explain what would happen to a cell if the cell
  • membrane did not do its job properly.

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D. Structure of the Cell Membrane

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1. Membrane Components
Proteins (peripheral integral)
Phospholipids
Cholesterol
Carbohydrates (glucose)
14
a. Phospholipids
  • 1. Make up the cell membrane

a. Contains 2 fatty acid chains that are nonpolar
b. Head is polar contains a PO4 group

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FLUID MOSAIC MODEL
  • 1. FLUID- because individual phospholipids and
    proteins can move around freely within the layer,
    like its a liquid.
  • 2. MOSAIC- because of the pattern produced by the
    scattered protein molecules when the membrane is
    viewed from above.

20
Cell Membrane
Polar heads are hydrophilic water loving
Nonpolar tails are hydrophobic water fearing
Makes membrane Selective in what crosses
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Cell Membrane
Hydrophobic molecules pass easily hydrophillic
DO NOT
The cell membrane is made of 2 layers of
phospholipids called the lipid bilayer
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Solubility
  • Materials that are soluble in lipids can pass
    through the cell membrane easily

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Semipermeable Membrane
Small molecules and larger hydrophobic molecules
move through easily. e.g. O2, CO2, H2O

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Semipermeable Membrane
Ions, hydrophilic molecules larger than water,
and large molecules such as proteins do not move
through the membrane on their own.
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