 Macromolecules are polymers made through
dehydration synthesis (reaction that removes a
molecule of water).
 Examples of macromolecules are:
 Carbohydrates – sugars
 Proteins- amino acids
 Lipids- fatty acids and glycerol
 Nucleic acids – nucleotides
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 Composed of monosaccharaides, disaccharides and
polysaccharides.
 Monosaccharaides: simple sugars that contain a ratio
of C:H:O of 1:2:1
 Examples
glucose, fructose and galactose
 Disaccharides: composed of 2 monosaccharaides
 Examples
sucrose, maltose and lactose
 Polysaccharides: chain of 3 or more monosaccharaides.
 Starch, glycogen and cellulose
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 Sugars with free carbonyl groups are called reducing sugars.
 They cause the copper (Cu ²⁺) in the Benedict’s reagent to become reduced
(gain electrons) to form Cu ¹⁺, forming Cu₂O .
 The reaction occurs when the mixture is heated to 100 °C.
Before the addition of Benedict’s reagent
water
glucose
sucrose
starch
milk
apple juice potato
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 After the addition of the
Benedict’s reagent
Water glucose sucrose starch milk apple potato
juice juice
 After the application of heat for 3
minutes.
RESULTS:
Blue= negative
Red = high concentration
Orange and yellow = medium concentration
Green = low concentration
-
+
-
-
+
+
+
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 Starch is a polysaccharide consisting of many glucose monomers linked
together into long branching chains. It is the primary storage carbohydrate in
plants. In the presence of iodine (I₂-KI) a solution containing starch will turn
blue-black in color.
 The test tube rack contains substances to be tested.
water
glucose
sucrose
starch
milk
apple
juice
potato
juice
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Blue-black = positive
Yellow = negative
water
glucose
sucrose
starch
milk
apple
juice
potato
juice
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 Some water, 10 drops of oil, 5 drops of Sudan
IV were added to a tube.
 Detergent water was added to the test tube
and mixed. Detergent is an emulsifier. It
surrounds the oil droplets and allows them
to stay suspended in the water. The
suspended oil droplets stained with Sudan
IV give color to the solution. This is an
emulsion.
 After the test tube sits, the oil will separate
from the water.
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 In the presence of proteins, biuret reagent reacts with the peptide
bonds between the amino acids changing in color from light blue to
violet. The intensity of the violet color is proportional to the protein
concentration. Biuret reagent does not react with free amino acids.
Solutions tested for proteins
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Light blue= negative
Violet = positive
End
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