Biology 2485B Lecture Notes - Lecture 5: Phospholipid, Glycerophospholipid, Sphingolipid
Section 05: Membranes and Membrane Proteins
Biomembranes Membranes define what is a cell. Allow specialized functions to occur in a localized
manner. Basic components: Lipids, Sterols and Proteins.
- Due to amphipathicity, phospholipids spontaneously form lipid bilayers in aqueous solution where
properties of the fatty acids confer properties onto the bilayers.
Fatty Acid
- Long hydrocarbon chain attached to a polar carboxyl head group
- Amphipathic.
- Often Cx:y, where x = number of carbon molecules, y = number of double bonds.
- No double bonds = saturated.
- One double bond = unsaturated.
- More than one double bond = polyunsaturated.
- Melting point increases with increasing chain length (more interactions), but melting point decreases
with increasing unsaturation (adding dble. bonds = harder to pack = more fluid at lower temperature).
- Fatty acids used as components of membrane lipids – phospholipids, phosphoglycerides, sphingolipids
etc. (and sterols).
Properties of Biomembranes
1. Fluid
2. Closed compartments
3. Semi-permeable
4. Asymmetric
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Document Summary
Biomembranes membranes define what is a cell. Allow specialized functions to occur in a localized manner. Due to amphipathicity, phospholipids spontaneously form lipid bilayers in aqueous solution where properties of the fatty acids confer properties onto the bilayers. Long hydrocarbon chain attached to a polar carboxyl head group. Often cx:y, where x = number of carbon molecules, y = number of double bonds. More than one double bond = polyunsaturated. Melting point increases with increasing chain length (more interactions), but melting point decreases with increasing unsaturation (adding dble. bonds = harder to pack = more fluid at lower temperature). Fatty acids used as components of membrane lipids phospholipids, phosphoglycerides, sphingolipids etc. (and sterols).
