This slide is for lecture purpose for undergraduate students in basic and medical science.

1. 11/23/2014
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TAG BIOSYNTHESIS AND STORAGE
Department of Biochemistry, Kathmandu Medical College, Duwakot, Nepal
Sunday, November 23, 2014
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@bloggerjesh
Fatty acids, lipids and triglycerides (TAG)
Sunday, November 23, 2014
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Fatty acids: carboxylic acid with hydrocarbon chain ranging from C4 to C36.
Lipids: chemically diverse groups of compounds, insoluble in water.
Triacylglycerol (TAG): (3 fatty acids + 1 glycerol)  simplest lipid constructed from fatty acids.
@bloggerjesh
Triacylglycerol (TAG)
Simplest lipid constructed from fatty acids are triacylglycerols.
Also known as fats, triglycerides or neutral fats.
Example: tripalmitin, tristearin, and triolein
Sunday, November 23, 2014
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@bloggerjesh
Triacylglycerol (TAG)
Sunday, November 23, 2014
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@bloggerjesh
Triacylglycerol (TAG)
Hydrophobic, non-polar, insoluble water, lower specific gravity than water.
TAG provides stored energy and insulation.
Types
Simple
Mixed
Sunday, November 23, 2014
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@bloggerjesh
Triacylglycerol
Sunday, November 23, 2014
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Simple vs. complex triacylglycerol – which one is more common?
Properties of TG
Nonpolar, hydrophobic and essentially insoluble in water.
Lower specific gravity than water.
Provide stored energy and insulation.
@bloggerjesh

2. 11/23/2014
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What is the biomedical importance of triacylglycerol (TAG)?
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Structural component of the membrane
Precursor of the hormones like “prostaglandins”.
Esterified fatty acid are stored in adipose tissue that act as a major energy reserve of the body.
@bloggerjesh
Triacylglycerol (TAG)
Lipases are present in “Adipocytes” and “germinating seeds” for hydrolysis of stored TG.
Releases fatty acids and transported to the site where it is required as fuel.
…advantages of using TAG as stored energy form rather than polysaccharides such as starch and glycogen?
Sunday, November 23, 2014
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@bloggerjesh
Triacylglycerol (TAG) Biosynthesis
Fatty acid fuels from three sources:
1. From FAT consumed in diet
2. FAT stored in cells as lipids
3. FAT synthesized in organs
70 kg man stores 15 kg of TAG which is enough to supply energy for 12 weeks, unlike Glycogen.
Sunday, November 23, 2014
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@bloggerjesh
Biosynthesis of TAG
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Adipose tissue lacks GLYCEROL KINASE!
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TAG biosynthesis
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Liver
Liver and adipose tissue
Why do some alcoholics have high VLDL level?
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TAG biosynthesis
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3. 11/23/2014
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Regulation of TAG biosynthesis by Insulin
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Triacylglycerol cycle
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Fates of TAG in the liver and adipose tissue
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In adipose tissue
Stored in cytosol of the cells in anhydrous form
Serves as “depot fat”
Small amount is stored in the liver
Most of them are exported, packaged with cholesteryl esters, cholesterol, phospholipids and proteins such as apoB-100 to form lipoprotein particle called VLDL.
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Synthesis, processing and secretion of VLDL
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Storage of TG in adipose tissue
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