Biosynthesis and storage of tag

11/23/2014

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TAG BIOSYNTHESIS AND

STORAGE

Department of Biochemistry, Kathmandu Medical College,

Duwakot, Nepal Sunday, November

23, 2014

1 @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


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Hydrophobic, non-polar, insoluble water, lower specific gravity than water.

TAG provides stored energy and insulation.

Types

Simple

Mixed


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Triacylglycerol


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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

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.

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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?


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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.


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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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11/23/2014

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Regulation of TAG biosynthesis by

Insulin 13

Sunday, November 23, 2014 @bloggerjesh

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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Biosynthesis and storage of tag

Science

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