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Carbo, Lipid & Proteins PreLab
Lipids (Fats/Oils)
Lipids are organic compounds
consisting of carbon, hydrogen and oxygen that are soluble in a variety
of organic solvents but insoluble in water. Included in this 
heterogeneous
group of organic molecules are fats, oils, steroids and phospholipids.
Fats and oils are storage forms of lipids commonly referred to as triglycerides.
Saturated Fatty Acid (left)
They are comprised of three fatty acid molecules attached to a glycerol molecule. At room temperature, fats are solid (generally those found in animal tissues) and oils are liquid to semi-liquid (generally those found in plant tissues). Fats and oils are particularly important in biological systems as sources of energy and as structural components of cells.
The
difference in the structure between saturated and. unsaturated fatty
acids gives them different chemical properties.
Unsaturated fatty Acid (left)
Saturated fatty acids
can align closely together so lipids containing primarily saturated
fatty acids are usually solid at room
temperature
(aka Fat).The C=C double
bond(s) in unsaturated fatty acids causes the molecule to "bend" (a
fatty acid with one C=C bond
is mono-unsaturated, a fatty acid with several C=C bonds
is poly-unsaturated).
Because they are "bent", unsaturated fatty acids are less able to interact and lipids contain primarily unsaturated fatty acids are liquid at room temperature (oils).
TriGylceride (left)
Sudan IV Test In this reaction, you will be testing for the presence of lipids. The lipid used for your positive control is oil. The negative control is water. Like lipids, the chemical Sudan IV is not soluble in water; it is, however, soluble in lipids. Therefore to test for the presence of lipids in a solution you will use a Sudan IV Test. In this test, if lipids are present the Sudan IV will stain them reddish-orange, giving a positive test.
NOTE: Sudan IV will stain skin and clothing. Handle with care!
Sudan IV Lipid test
