Lipids

Question 1

Describe lipid nomenclature

Answer 1

• 1.) X:Y∆n or 2.) X:Y 𝜔-n
• X = number of carbons
• Y = number of double bonds
• n = carbon atom that forms double bond
• X:Y∆n – counting from carboxyl end
• X:Y 𝜔-n
 – counting from 𝜔-carbon
• Sequential double separated by a methylene group ( – CH2 – )

Formula 1 lists ALL double bonds in the compound
Formula 2 only lists the FIRST double bond from 𝜔 end

Question 2

What is a triacylglycerol?

Answer 2

3 fatty acids joined to a glycerol backbone
• Esterified
• Diacylglycerol = glycerol + 2 fatty acids
• Monoacylglycerol = glycerol + 1 fatty acid
no charge

acyl groups may be saturated or unsaturated

Question 3

What are phosphoglycerides? What are sphingomyelins?

Answer 3

Phosphoglycerides
• Glycerol, fatty acids (C1 and C2), phosphate (C3) and alcohol
• Saturated fatty acid at C1, Unsaturated at C2

Sphingomyelins contain sphingosine instead of glycerol

Question 4

What are the functions of phospholipases? (4)

Answer 4

Hydrolyze ester bond on phospholipids
• Classified according to where they cleave (PLA1, PLA2, PLC etc.)

Membrane remodeling
• Unsaturated : saturated FA ratio affects flexibility
• Replace damaged FA’s

Signal Transduction
• PLC -> IP3 , DAG -> Ca2+ release, PKC activation
• PLA2 -> arachidonic acid -> prostaglandins synthesis

Digestion
• Pancreatic phospholipases break down dietary phospholipids
• Lysosomal phospholipases break down membrane component