Carbohydrates
Cue Notes
Glossary Monomer: A single repeating unit of a polymer.
Polymer: A large molecule comprising of repeating units, monomers, bonded together.
Condensation reaction: A reaction where 2 molecules bond together to form a larger
molecule with the elimination of a water molecule.
Alpha glucose: An isomer of glucose with the first -OH facing the opposite direction to the
CH2OH
Beta glucose: An isomer of glucose with the first -OH facing the same direction to the
CH2OH
Isomer: Molecules that have the same chemical formula but have a different arrangement.
1-4 glycosidic bond: A bond between the C1 on the first monomer and C4 on the second
monomer.
1-6 glycosidic bond: A cross link bond between C1 on one molecule and C6 on another
(creating a branch)
Disaccharide: 2 monosaccharide molecules bonded together with a glycosidic bond.
Polysaccharide: Large molecules with many monomer linked with glycosidic bonds.
Amylose: A form of starch (with only alpha-glucose): a linear unbranched polysaccharide
containing only 1-4 glycosidic bonds which coils into a helix
Amylopectin: A form of starch (with only alpha-glucose): the same as amylose but has 1-6
glycosidic bonds which form branches every 24-30 glucose molecules.
Glycogen: The main storage product in animals: the same as amylopectin but the 1-6 bonds
are every 8-10 glucose molecules, more branched.
Cellulose: A structural polysaccharide found in plant cell walls.
Chitin: A structural polysaccharide found in the exoskeletons of insects and fungi cell walls.
Microfibrils: Parallel chains of cellulose molecules cross linked with H-bonds to form a
bundle.
Alpha vs Beta glucose Glucose exists in both straight chain and ring form, with rings forming when glucose is dissolved in
water
Formations of Disaccharides
Benedict’s test for sugar Tests for reducing sugars (those that donate an electron to copper (||) ions in copper
sulphate solution [blue] to turn it to copper(|) ions [brick red])
1. Equal volumes of benedict’s solution and test solution heated to 70 oC
2. If reducing sugar is present solution will change colour blue(negative) green(V low)
yellow (low)orange(medium) red (high){precipitate}. Qualitative test.
If it’s a non-reducing sugar then it needs to be broken down with HCl+ heat, then an alkali is
added for pH>7. If it changes colour then a non-reducing sugar was initially present.
Enzymes could also be used to break down disaccharides or a bio sensor could be used to
precisely measure the concentrations, useful for diabetes.
Cue Notes
Glossary Monomer: A single repeating unit of a polymer.
Polymer: A large molecule comprising of repeating units, monomers, bonded together.
Condensation reaction: A reaction where 2 molecules bond together to form a larger
molecule with the elimination of a water molecule.
Alpha glucose: An isomer of glucose with the first -OH facing the opposite direction to the
CH2OH
Beta glucose: An isomer of glucose with the first -OH facing the same direction to the
CH2OH
Isomer: Molecules that have the same chemical formula but have a different arrangement.
1-4 glycosidic bond: A bond between the C1 on the first monomer and C4 on the second
monomer.
1-6 glycosidic bond: A cross link bond between C1 on one molecule and C6 on another
(creating a branch)
Disaccharide: 2 monosaccharide molecules bonded together with a glycosidic bond.
Polysaccharide: Large molecules with many monomer linked with glycosidic bonds.
Amylose: A form of starch (with only alpha-glucose): a linear unbranched polysaccharide
containing only 1-4 glycosidic bonds which coils into a helix
Amylopectin: A form of starch (with only alpha-glucose): the same as amylose but has 1-6
glycosidic bonds which form branches every 24-30 glucose molecules.
Glycogen: The main storage product in animals: the same as amylopectin but the 1-6 bonds
are every 8-10 glucose molecules, more branched.
Cellulose: A structural polysaccharide found in plant cell walls.
Chitin: A structural polysaccharide found in the exoskeletons of insects and fungi cell walls.
Microfibrils: Parallel chains of cellulose molecules cross linked with H-bonds to form a
bundle.
Alpha vs Beta glucose Glucose exists in both straight chain and ring form, with rings forming when glucose is dissolved in
water
Formations of Disaccharides
Benedict’s test for sugar Tests for reducing sugars (those that donate an electron to copper (||) ions in copper
sulphate solution [blue] to turn it to copper(|) ions [brick red])
1. Equal volumes of benedict’s solution and test solution heated to 70 oC
2. If reducing sugar is present solution will change colour blue(negative) green(V low)
yellow (low)orange(medium) red (high){precipitate}. Qualitative test.
If it’s a non-reducing sugar then it needs to be broken down with HCl+ heat, then an alkali is
added for pH>7. If it changes colour then a non-reducing sugar was initially present.
Enzymes could also be used to break down disaccharides or a bio sensor could be used to
precisely measure the concentrations, useful for diabetes.
