Cell%20Membrane%20Plasma%20Membrane%20Phospholipid%20Bilayer%20Semipermeable%20Membrane

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Cell MembranePlasma MembranePhospholipid
BilayerSemipermeable Membrane

• Ch. 7
• 7.1-7.2

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Function of the Cell Membrane

• MAINTAIN HOMEOSTASIS
• (Stable internal environment)

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The Gatekeeper

• Selectively permeable allows some substances to
  cross more easily than others
• Made mainly of lipids proteins

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Fluid Mosaic Model

• Membrane is a fluid structure with a mosaic of
  various proteins
• Lipids some Proteins move laterally
• Some Proteins are held still by the cytoskeleton

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Proteins determine function

• 1. Integral many (not all) are transmembrane
• 2. Peripheral not embedded in bilayer

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What moves in and out of the Cell Membrane?

• Small molecules ions move in out at different
  rates.
• Some move easily, some need help from proteins

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Transport Proteins

• Allow substances to pass avoiding contact with
  the lipid bilayer.
• Channel Proteins act like a tunnel through the
  membrane. Pg. 131
• Carrier Proteins carry substances change
  their shape to accommodate pass through the
  membrane.
• Specific for the substances it moves

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Carrier Protein Example

• Glucose has a specific carrier protein to help it
  move across the membrane.
• The protein rejects fructose b/c it is specific
  for Glucose only.
• (Ex. On pg. 131)

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Animation