Topic 1.1 Monomers and Polymers and 1.2 Carbohydrates
Monomer - Smaller units, identical or similar, from which larger molecules are made.
Polymer - Molecules made from a large number of monomers joined together.
Condensation Reaction - Joins two molecules together with the formation of a chemical bond and involves the
elimination/removal of a water molecule.
Hydrolysis Reaction - Breaks a chemical bond between two molecules and involves the addition of a water
molecule.
Polymer Monomer
Carbohydrates Glucose
Proteins Amino Acids
Nucleic Acids Nucleotides
Lipids are NOT polymers - Made up of different monomers. Triglycerides do not chemically join with other
triglycerides as they are all different.
Carbohydrates contain the elements:
- Carbon - Oxygen - Hydrogen
They are split into 3 groups known as:
Monosaccharides (Monomers) - One sugar
Disaccharides (Dimers) - Two sugars
Polysaccharides (Polymers) - Many sugars
Monosaccharides and disaccharides are sweet, small and soluble whereas polysaccharides are large, insoluble
and not sweet.
Monosaccharides
There are 3 types:
Glucose, Fructose and Galactose - They all have the same molecular formula but different structures (isomers).
The most important monosaccharide is glucose.
Carbon 1 - The hydroxyl group and hydrogen have been
switched in beta glucose compared to alpha glucose.
Formation of Maltose through condensation reaction:
, Maltose Molecular Formula = C12H22011
3 Main Disaccharides:
Glucose + Glucose = Maltose
Glucose + Fructose = Sucrose
Glucose + Galactose = Lactose
Polysaccharides:
- Starch - Cellulose - Glycogen
Chemical Tests
Test for starch is iodine. If the solution turns blue/black, starch is present.
Test for simple carbohydrates is heating with benedict's reagent. If reducing sugar is present, solution turns green
(least concentrated), yellow, orange or brick red (most concentrated)
Starch
Amylopectin = Branched chains of alpha glucose molecules.
This provides a large SA for rapid hydrolysis by enzymes releasing alpha glucose for respiration. It has 1-6 and 1-4
glycosidic bonds
Amylose = Long and straight chains of alpha glucose which coil into a helix.
This structure is compact so is good for storage - Large amount in a small space.
It has 1-4 glycosidic bonds only.
Starch is insoluble so has no effect on water potential - Osmosis does not occur and cause cell lysis. It is also too
large to pass through the cell membrane.
Glycogen
It has shorter chains, so it is more readily available to be hydrolysed into glucose - Due to higher metabolic rate of
animals and humans compared to plants. It is more highly branched therefore has a larger surface area. It is
stored in muscles and liver.
Glycogen is insoluble so does not affect water potential or diffuse out of cells.
Cellulose
It is made up of beta glucose molecules and has only 1-4 glycosidic bonds.
Beta glucose molecules join together through condensation reactions to form long straight, unbranched chains
that are parallel to one another.
Every other beta glucose molecule rotates 180° to allow OH groups on carbon 1 and 4 to be adjacent to each other
to form a glycosidic bond.
Several chains of cellulose are joined together in layers; these chains are held together by the formation of
hydrogen bonds formed between OH groups. Many chains joined by hydrogen bonds form a microfibril - many
microfibrils joined together form cellulose fibre to provide strength.
Topic 1.3 Lipids
Monomer - Smaller units, identical or similar, from which larger molecules are made.
Polymer - Molecules made from a large number of monomers joined together.
Condensation Reaction - Joins two molecules together with the formation of a chemical bond and involves the
elimination/removal of a water molecule.
Hydrolysis Reaction - Breaks a chemical bond between two molecules and involves the addition of a water
molecule.
Polymer Monomer
Carbohydrates Glucose
Proteins Amino Acids
Nucleic Acids Nucleotides
Lipids are NOT polymers - Made up of different monomers. Triglycerides do not chemically join with other
triglycerides as they are all different.
Carbohydrates contain the elements:
- Carbon - Oxygen - Hydrogen
They are split into 3 groups known as:
Monosaccharides (Monomers) - One sugar
Disaccharides (Dimers) - Two sugars
Polysaccharides (Polymers) - Many sugars
Monosaccharides and disaccharides are sweet, small and soluble whereas polysaccharides are large, insoluble
and not sweet.
Monosaccharides
There are 3 types:
Glucose, Fructose and Galactose - They all have the same molecular formula but different structures (isomers).
The most important monosaccharide is glucose.
Carbon 1 - The hydroxyl group and hydrogen have been
switched in beta glucose compared to alpha glucose.
Formation of Maltose through condensation reaction:
, Maltose Molecular Formula = C12H22011
3 Main Disaccharides:
Glucose + Glucose = Maltose
Glucose + Fructose = Sucrose
Glucose + Galactose = Lactose
Polysaccharides:
- Starch - Cellulose - Glycogen
Chemical Tests
Test for starch is iodine. If the solution turns blue/black, starch is present.
Test for simple carbohydrates is heating with benedict's reagent. If reducing sugar is present, solution turns green
(least concentrated), yellow, orange or brick red (most concentrated)
Starch
Amylopectin = Branched chains of alpha glucose molecules.
This provides a large SA for rapid hydrolysis by enzymes releasing alpha glucose for respiration. It has 1-6 and 1-4
glycosidic bonds
Amylose = Long and straight chains of alpha glucose which coil into a helix.
This structure is compact so is good for storage - Large amount in a small space.
It has 1-4 glycosidic bonds only.
Starch is insoluble so has no effect on water potential - Osmosis does not occur and cause cell lysis. It is also too
large to pass through the cell membrane.
Glycogen
It has shorter chains, so it is more readily available to be hydrolysed into glucose - Due to higher metabolic rate of
animals and humans compared to plants. It is more highly branched therefore has a larger surface area. It is
stored in muscles and liver.
Glycogen is insoluble so does not affect water potential or diffuse out of cells.
Cellulose
It is made up of beta glucose molecules and has only 1-4 glycosidic bonds.
Beta glucose molecules join together through condensation reactions to form long straight, unbranched chains
that are parallel to one another.
Every other beta glucose molecule rotates 180° to allow OH groups on carbon 1 and 4 to be adjacent to each other
to form a glycosidic bond.
Several chains of cellulose are joined together in layers; these chains are held together by the formation of
hydrogen bonds formed between OH groups. Many chains joined by hydrogen bonds form a microfibril - many
microfibrils joined together form cellulose fibre to provide strength.
Topic 1.3 Lipids
