Biol 217-Lecture 2- Lipids 1: Lipids and Membranes

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  • Created by: hope ball
  • Created on: 14-12-12 09:42

Lipids 1: Lipids and membranes 

What are lipids?

  • Diverse class of molecules
  • Rich in Carbon and Hydrogen, but few Oxygen molecules
  • Most are not soluble in water
  • Many are amphiphathic
  • They have a Polar, hydrophillic head and a Non polar hydrophobic tail

Lipids are split into Fatty acids (Eicosanoids, Triacylglycerols, Waxes, Sphingolipids), Phospholipids (Phosphatidates), Glycolipids and Polyprenyl compounds (Steroids).

Fatty Acids

  • There are over 100 different fatty acids
  • R-COOH structure
  • They differ in level of unsaturation and the length of their hydrocarbon tail
  • Their melting point depends on their degreee of unsaturation and position of the double bonds
  • Saturated= no C=C e.g. Stearate (C18)
  • Monounsaturated= 1 C=C e.g. Oleate (C18)
  • Polyunsaturated= more than one C=C e.g. Linolenate (C18)
  • Omega fatty acids (w) e.g. "w-3 fatty acid"- 20C,double bond every 3 Carbons, w on 1
  • "Cis and trans" fatty acids- e.g. Oleic aid (Cis) and Elaidic acid (Trans)

Fatty acid in the living cell

  • C12-C20, even number
  • Free fatty acids only in traces
  • Essential fatty acids

Triacylglycerols (Triglycerides)

  • A triacylglycerol molecule is a Glycerol compound with 3 fatty acids attached via an Ester bond. O=C-O
  • Triacylglycerols are the most abundant lipids in human food
  • Fats: Solid at room temperature, Long-chained, saturated fatty acids
  • Oils: Liquid at room temperature, Shorter-chained, more unsaturated fatty acids
  • Triacylglycerols storage- They have a high energy content and hydrophobic. Anhydrous storage and form adipocytes. 
  • They are the most abundant lipids in mammals
  • They are NOT found in membranes
  • They are NOT amphipathic


  • Most abundant lipids in biological membranes
  • Amphipathic
  • Glycerol…


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