Download Lipids

Lipids
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Include substances commonly called fats, oils
and waxes.
Made up of C, H and O but relatively less
oxygen than in carbohydrates.
Dissolve in organic solvents but not in water
(hydrophobic)
Formed from the combination of fatty acids and
glycerol.
Functions of Lipids
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Reserve Energy Supply - Fats yield more than twice as
much energy as carbohydrates when broken down.
Component of cell structure, especially cell membrane
Act as cushion for delicate organs
Help to retain body heat (insulation)
Serve as carriers for vitamins A, D, E, K
Act as the raw material for the synthesis of hormones.
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A fatty acid molecule consists of a chain of
carbon atoms to which hydrogen atoms are
bonded. At one end of the chain there is a
carboxyl group COOH.
Carboxyl group
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Glycerol – is an alcohol that has three OH
groups in its molecule.
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A molecule of fat (triglyceride) is produced by
the combination of three fatty acid molecules
with one glycerol molecule. A condensation
reaction takes place between a hydroxyl group
of the glycerol and the carboxyl group of a fatty
acid.
The bond is called an ester linkage.
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Saturated Fats – A fat formed from fatty acids
in which all carbon-to-carbon bonds are single
bonds.
Unsaturated Fats – A fat formed from a fatty
acid in which there are one or more double or
triple carbon-to-carbon bonds.
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Waxes – Fatty acids combined with either
alcohols or other hydrocarbons that form a
hard, water-repellent covering.
Waxes coat leaves, fruit, fur, and feathers
making them water repellent.
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Steroids (sterols) – Lipids that have four
interconnected carbon rings with various side
chains.
Cholesterol is an important steroid component
of cell membranes. It is used to produce bile
salts and vitamin D. Forms the sex hormones
e.g. estrogen and testosterone.
Cortisone
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Phospholipids – Consists of glycerol attached
to 2 (not 3) fatty acids chains. A phosphate
group attaches to the third hydroxyl group of
glycerol. Forms a major part of cell membranes.
Micelles – spheres
formed when
phospholipids are
added to water
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Questions p. 40 #11, 12 & 16
Questions on handout