Transcript Unit 5 Macromolecules

Unit 5
Macromolecules
Macromolecules
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Molecules that make up living things
Carbon-based molecules
Carbohydrates
Lipids
Proteins
Nucleic acids
Macromolecules, continued
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Composed of subunits called monomers
Many monomers make a polymer
Monomers linked by covalent bonds
Process called dehydration synthesis (OR,
condensation) because a water molecule
is given off when the bond between
monomers forms
Figure 3.3 Condensation and Hydrolysis of Polymers (Part 1)
Hydrolysis
• Breaking down polymers to monomers
• Requires addition of water molecule
Figure 3.3 Condensation and Hydrolysis of Polymers (Part 2)
Carbohydrates
• Sugars, starches
• Monosaccharides
– Glucose
• Disaccharide
– Sucrose
– Formed by glucose covalently bonded to
fructose
• Polysaccharides
– Starch, glycogen, cellulose
Benedict’s test
• Benedict’s reagent tests for the presence
of a free carbonyl group
• Sugars with a free carbonyl group are
called reducing sugars
• Monosaccharides are reducing sugars
• Some disaccharides are reducing sugars
Method for Benedict’s
• Test 8 different substances for the presence of
reducing sugars.
• Add Benedict’s reagent to substance, mix.
• Heat for 3 minutes in boiling water.
• Place all tubes in a beaker of boiling water.
• Use test tube tongs.
• Look for color change.
– Orange-red is a positive reaction.
Iodine test for starch
• Starch is also a carbohydrate (a
polysaccharide)
• Starch turns blue-black in the presence of
iodine.
Lipids
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Lipids are insoluble in water
Hydrophobic
Lipids clump together in water
Examples:
– Fats, steroids, waxes, oils
Sudan IV test for lipids
• Observe what happens when oil is added
to water
• Add 5 drops of Sudan IV and mix. In
which of the liquids is the dye soluble?
• Add detergent to this mixture and mix.
What happens to the pink color?
Proteins- Biuret Test
• Composed of monomers called amino
acids
• Linked together by peptide bonds
• Biuret reagent reacts with the peptide
bonds to change color from light-blue to
violet.
• Test 8 substances for the presence of
proteins
Figure 3.5 Formation of Peptide Linkages
Hydrolysis of macromolecules
• Polymers are broken down by hydrolysis
reactions
• Bonds are broken by the addition of water
• Test what happens when starch and
sucrose are hydrolyzed.
• Hydrolysis in this case is caused by
– Boiling
• Test for hydrolysis with no heat
– Tubes # 1, 2, and 3.
• Test for hydrolysis by heating 10 minutes
– Tubes # 4, 5, 6.
• Test for hydrolysis by heating 20 minutes
– Tubes 7, 8, 9.
• For each set you will perform Benedict’s
test and Iodine test.
• Develop a hypothesis. In which tube
would you expect to positive reaction for
starch and reducing sugars? Why?
• (You will need to know which sugars are
reducing sugars. Do some internet
research this information.)
• Complete chart of colorimetric tests