Biological macromolecules carbohydrates, lipids, proteins, nucleic acids
Unit 5 Macromolecules. Molecules that make up living things Carbon-based molecules Carbohydrates...
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Transcript of Unit 5 Macromolecules. Molecules that make up living things Carbon-based molecules Carbohydrates...
Unit 5
Macromolecules
Macromolecules
• Molecules that make up living things
• Carbon-based molecules
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
Macromolecules, continued
• 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
• 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