The Cell Membrane

1
The Cell Membrane

• aka PLASMA membrane

2
Membrane makeup (proteins and lipids)

• Phospholipids
• Cholesterol (reduces fluidity)
• Oligosaccharides
• Glycolipids (head is sugar)
• Glycoproteins (stick outside of cell)
• Proteins
• Integral (embedded within membrane)
• Peripheral (inside of membrane)

3
Fluid Mosaic Model

• Phospholipids arranged in a bi-layer

Polar head hydrophilic (face out)
Nonpolar tails hydrophobic (face in)
4
The Membrane
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The Mosaic

• Each membrane has unique proteins
• Determine cell function
• Channel proteins particular molecules move
  freely
• Carrier proteins selectively interact with
  molecules
• Receptor proteins have a specific shape

6
Fluidity

• At room temperature olive oil
• More unsaturated fats more fluidity
• Tails wiggle and can switch places in the
  membrane
• Some proteins are held in place by the
  cytoskeleton

7
Cell-to-cell Recognition

• Glycolipids and glycoproteins are used to
  identify cell
• Vary in length, type of sugar and branching
• Lead to transplant rejection
• Gives us blood types (8 total)