BIOC 2300 Lecture Notes - Lecture 12: Adipose Tissue, Ester, Carboxylic Acid
3 May 2018
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Department
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Lipids and Membranes
February 1st, 2016
Lipids: An overview
• Lipids are very heterogenous, hydrophobic (or amphipathic) and thus insoluable (storage
and transport is a challenge)
• Lipids associate into bilyaers, vesicles, micelles, droplets and can complex with proteins
but are rarely free in a solution
• Classified by structure:
o Fatty acids (FAs: alipathic carboxylic acids)
o Triaclyglycerides (TAGs: 3 FAs esterified to glycerol)
o Phospholipids (PLs: phosphor-head gropu attached to Diacylglycerol or ceramide)
o Isoprenoids/steroids
o Glycolipids
Fatty Acids:
• Amphipathic: hydrophilic carboxyl group and hydrophobic hydrocarbon tail
• FAs may be saturated (no double bonds), mono/poly-unsaturated – double bond positions
are specified from COOH end or tail (omega nomenclature) **ex. 18:0 = 18 carbons, no
double bonds
• Cis = same side; trans = opposite
• Most natural unsaturated FAs have unconjugated cis double bond
• Some essential FAs must be obtained from the diet
• In humans, most Fas are found esterified to cholesterol or to glycerol (TAGs or PLs) or
are bound to albumin in the blood
• FAs are also used to make important signalling molecules, such as eicosanoids
• Two types of Nomenclature:
o Count carbons starting from COOH – list position of double bonds ex.
18.3(9,12,15)
o Count carbons starting from tail to the first double bond next carbon is the
omega carbon next is the alpha
▪ 18.3(n-3) OR 18.3w-3
• Fatty Acid derivatives – important for biosignalling *Arachiodonic acid (20:4) is the
precursor of eicosanoids
o Soap = Na+ salts of FAs
o Waxes – consist of FA….
Traicylglyercols:
• 3 FAs esterified to glycerol: they are found in circulating liproteins or in insoluble
cytosolic lipid droplets *nonpolar; hydrophobic
• TAG in lipoproteins are delivered in the blood to peripheral tissues as a fuel source, or
for food storage in adipose tissue
• In adipose tissue, stored TAG in droplets can be hydrolyzed to release FFA and glycerol
for delivery to the liver and other tissues
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