Lipids Flashcards
Hydrophobicity of fatty acids is due to
Predominant hydrocarbon chain
What are simple and complex lipid
Simple lipids are those that yields two types of products on hydrolysis.
Complex lipids yields two or three types of products on hydrolysis.
Fatty acids
Simplest form of lipids. Have a long chain hydrocarbon with one carboxylic group. It is amphipathic in nature.
Essential fatty acids
Fatty acids that are not synthesized in the human body. Example linoleate and linolenate.
What affects the melting point of fatty acids
The longer the chain, the higher the melting point. Greater the number of double bonds the lower the melting point.
How does the chain length affects the solubility in water
The longer the fatty acyl chain and fewer the double bonds the lower is the solubility in water
Triacylglycerol
They have three fatty acid chain and one glycerol.
Non polar and neutral and hydrophobic in nature
Major storage form of lipids
Triacylglycerol
Saponification
Hydrolysis of triacylglycerol with an alkali such as NaOH or KOH
Waxes. Eg.
Esters of fatty acids.
Beeswax from bees have triacontanyl palmitate.
Carnauba wax from Copernicia prunifera
Ether glycerophospholipid
Possesses an ether linkage at C1 carbon of glycerol. Eg. Platelet accumulating factor
Plasmalogen
Ether glycerophospholipid in which alkyl moiety is cis a,b unsaturated
Steroid
Complex derivatives of triterpenes. Composed of four fused rings called steroid nucleus. Sterols are amphipathic in nature.
Cholesterol
Acts as a precursor for steroid hormones and bile salts. Not found in plants and fungi. 27 carbon compound has four rings and C3 has a OH group present. It keeps membrane fluid
Eicosanoids
Signalling molecules act locally.
Two types, prostanoids and leukotrienes.
Pathways of prostanoids and leukotrienes
Prostanoids - cyclooxygenase pathway
Eicosanoids - Lipoxygenase pathway
Prostanoids include?
Prostaglandins, prostacyclin and thromboxanes
Prostaglandins
Identified in human semen. All mammalian cells except RBCs produce them. Derivatives of prostanoic acid. Precursor arachidonic acid.
Precursor of prostaglandins and thromboxanes
Prostaglandins H2
Function of prostaglandins
Uterine contraction
Vasodilator
Low BP
Inflammation
Pain
Inhibitor of prostaglandins
Nonsteroidal anti inflammatory drugs
Thromboxanes
In blood platelets. Helps in clotting and vasoconstrictor.
Prostacyclin
Formed by PGH2 by enzyme prostacyclin synthase. Abundant in endothelial cells. Vasodilator and inhibits platelet aggregation
Leukotrienes
Derived from arachidonic acid. Do not have a ring. Occurs in leukocytes. Increases intracellular calcium. Decreases intracellular cAMP
