Be able to describe the relationship between fatty acids and triacylglycerol

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Lipids are hydrophobic non-- polar large molecules that are built from smaller molecules attached by covalent bonds. Examples of lipids are  fats, oils and waxes. 

A fat is composed of glycerol and three fatty acids. Glycerol is a type of alcohol with three carbons in the molecule to which a hydroxyl group is attached to every carbon. A fatty acid contains a carboxyl group attached to a long carbon skeleton to which hydrogens are bonded. The skeleton is usually between 16-18 carbons in length. Because of the covalent bonds between carbon and hydrogen which are non polar, the skeleton is hydrophobic and the reason why fats and water do not mix--the polar water molecules hydrogen bond to eachother and don't bond to the fats.

fat molecule is formed by dehydration synthesis when three fatty acids are joined to a glycerol molecule which forms a triacylglycerol (triglyceride). The bonds where the fatty acid join to the glycerol molecule are known as ester linkages. Each of the three fatty acids may be of the same type, or different fatty acids.

Therefore the relationship between fatty acids and triacylglycerol is that a fatty acid is a component of fat and a fat molecule itself contains three fatty acids attached to a molecule of glycerol--hence the word  triacylglycerol which refers to three of those fatty acid molecules which are present in a fat. The functions of fat are--energy storage, to cushion the internal organs and for insulation.

I have included a link with a diagram showing how the macromolecule fat is formed by dehydration synthesis from its smaller components--glycerol and three fatty acids.

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