Plasma Membrane Structure and Function

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Plasma MembraneStructure and Function
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Plasma Membrane Graphic
See Inside the Cell
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What is the plasma membrane made of?

• Made mostly of
• proteins
• phospholipids (two fatty acids and one phosphate
  group)

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What is the structure of the phospholipid?

• Two fatty acids - Tail
• Hydrophobic
• Directed Inward
• Phosphate group - Head - negatively charged
• Hydrophilic
• Directed Outward
• The structure of phospholipids enables them to
  form boundaries or membranes between two watery
  boundaries

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Phospholipid Sandwich

• Phospholipid Bilayer - a two-layer sandwich of
  molecules surrounds the cell
• The phosphate heads face the watery insides and
  watery outside of the cell

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What Can EASILY Pass?

• Nonpolar Molecules
• Oxygen
• Carbon dioxide

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What Cant EASILY Pass?

• Polar molecule
• Ions
• Sugars

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Membrane Lipids

• Phospholipids
• Glycolipids - used to identify the cell
• Cholesterol - responsible for keeping the
  membrane fluid

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Membrane Proteins

• Scattered randomly throughout each membrane is
  different
• Integral Proteins - Embedded in the membrane
• Peripheral Proteins - Attached to the membrane
• Membrane Animation

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Types of Membrane Proteins

• Enzymes - Carry out some of the cells important
  chemical reactions
• Membrane Proteins (Glycoproteins)- Help the cells
  communicate and recognize each other
• Cell to Cell Recognition
• Cell Signaling
• Transport Proteins - Help move certain substances
  such as water and sugar across the membrane
• Channel Proteins - allow a particular molecule to
  cross the membrane freely
• Carrier Proteins - interact with a specific
  molecule so it can cross the plasma
• Receptor Proteins - shaped so a specific molecule
  can bind to it.