Cell Boundaries

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Cell Boundaries

• Chapter 7-3

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Cell Membrane

• The cell membrane (plasma membrane) acts as a
  boundary between the cell and its environment
• Regulates homeostasis
• Selective because it allows only certain
  materials into and out of the cell

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Cell Membrane

• Whats it made of? The phospholipid bilayer!!
• Whats a phospholipid? 1. Glycerol backbone
• 2. Two
  fatty acid tails
• 3.
  Phosphate group

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Phospholipid
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Fatty Acid Tails

• Nonpolar!!! What does this mean? Equal
  distribution of charges!!
• Do not attract to polar molecules
• Hydrophobic

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Phosphate Head

• Polar!!! What does this mean? Unequal
  distribution of charges!
• Attracts to other polar molecules
• Hydrophilic!!

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The Phospholipid Bilayer
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The Fluid Mosaic Model

• A mosaic is a complete work composed of many
  parts
• The cell membrane is also composed of many parts
  working together to create a perfectly regulated
  barrier for the cell!

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The Fluid Mosaic Model

• What are the components of the phospholipid
  bilayer?
• 1. Phospholipids (In two layers bilayer)
• 2. Proteins
• 3. Cholesterol

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Cholesterol

• Cholesterol is a steroid. So, what type of
  organic compound is it?
• In the cell membrane, cholesterol acts to
  stabilize phospholipids
• It does this by keeping fatty acids from sticking
  together

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Protein

• Proteins embedded in the cell membrane help with
  molecular transport
• Allow molecules into and out of the cell!
• Make the cell semi-permeable

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Transport Protein
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Proteins

• Also help with cellular 1. Support
• 2.
  Flexibility
• 3.
  Identification
• 4.
  Enzymatic reactions
• 5. Cell to
  cell adhesion

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Cell Wall

• Not a part of animal cells!
• Found in plant cells, fungi and some prokaryotes
• Additional support to the cell membrane

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Cell Wall

• Whats its function? To provide support and
  protection for the cell
• Whats it made of? Carbohydrates and protein
• Cellulose is the main carbohydrate that
• composes the cell wall
• What is cellulose?

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Cell Wall
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Plant Cells

• Two major differences between plant and animal
  cells
• Cell wall, and therefore, presence of cellulose
• Large central vacuole to store large amounts of
  water

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Plant Cell
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Plant Cell