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1 Lipids

The lipids we'll be studying are phospholipids, the primary components of cellular membranes. Phospholipids are amphipathic; that is, they are both hydrophilic and hydrophobic. The "head" of a lipid moleule is negatively charged phosphate group and the two "tails" are highly hydrophobic hydrocarbon chains.

Phospholipid tails will congregate together to form a local hydrophobic environment. This leaves the charged phosphate groups facing out into the hydrophilic environment. There are three structures that phospholipids can form because of their ampiphatic nature. Each represents a phospholipid.

  1. micelles

  2. planar lipid bilayers

  3. spherical lipid bilayers (vesicles)

    A phospholipid bilayer is approximately 5 nm thick. This membrane is semipermeable, meaning that most molecules are excluded but some molecules are allowed to pass freely (diffuse) through the membrane.

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