Mr. Sover

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Lecture 8

• Mr. Sover

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Please Pass in Your Assignments

• P. 110 (1-3)

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Pass Back Homework and Review

• P. 96 (1-4)

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Mr. Sover made a Mistake

• F 1.8C 32

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The Cell and its Environment
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The First Discovery of Cells

• Robert Hooke, 1665
• Matthias Schleiden, 1838
• Plants are composed of cells and
• these cells are responsible for function
• Theodor Schwann, 1839
• Animals
• Rudolf Virchow, 1858

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Cell Theory

• 1. All organisms are composed of one or more
  cells.
• 2. The cell is the basic unit of structure and
  function in organisms.
• 3. All cells are produced from other cells.
• This is a theory because it is a major hypothesis
  that has withstood the test of time.
• Tissues

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Properties of the Plasma Membrane

• All cells are bathed in fluid.
• Cells must obtain materials from and release
  substances into their moist environment.

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• Since each cell is its own unit of life, it must
  have a boundary separating it from its external
  environment
• Selective permeability
• Tea bag

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The Lipid Bilayer

• The cell membrane is composed of two layers of
  molecules called phospholipids.Cell Membrane
  Bilayer
• Fatty acid tails and phosphate group heads

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Old Vs. New
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Most Important Role of the Plasma Membrane

• Structural Role

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The Proteins in the Plasma Membrane

• Regulate which particles cross the membrane
• Serve as enzymes which take part in chemical
  reactions
• Serve as markers for chemicals
• Disease
• Communication

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• Internal structures of cells also have membranes
• These membranes also have their own permeability
  characteristics.

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Consider the plasma membranes role as a
gatekeeper or bouncer
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Diffusion!
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Placing blue crystals of copper sulfate into a
beaker

• Initially these crystals sink to the bottom of
  the beaker.
• Then what?
• Nonrandom to random

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• The water stays blue because equal numbers of
  copper ions are entering and leaving any given
  region of water at any given time.
• Ionsrandom
• This is diffusion.

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Homework

• Please prepare flashcards for page 114, language
  of biology.