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AQA A Level Biology
3.1 Biological Molecules
3.1.1 Monomers and Polymers
3.1.2 Carbohydrates
3.1.3 Lipids
3.1.4 Proteins and Enzymes
3.1.5 Nucleic Acids and DNA replication
3.1.6 ATP
3.1.7 Water
3.1.8 Inorganic Ions
, Monomer Smaller, soluble molecule from which Monosaccharides Monomers from which larger carbs are Cellulose structure and function
larger molecules are made made (glucose, fructose, galactose)
1) many beta glucose molecules joining together to
Polymer Molecules made from many similar form long, straight and unbranched chains of cel-
Disaccharides two monosaccharides joined together
monomers joined together lulose
Breaking and Forming Polymers Polysaccharides the condensation of many repeating 2) These chains are held together by many hydrogen
Condensation reaction: monosaccharides (e.g. starch, glycogen, bonds to form microfibrils
cellulose)
• the joining of two molecules together 3) These provide strength and rigidity to the cell
• by a chemical bond Biochemical Tests
• involving the elimination of a water mole- Starch structure and function
cule Biochemical test to find reducing sugars
Hydrolysis reaction: 1) Starch is branched: providing a higher surface area
1) + benedict's solution and heat to 95 degrees
as there are more ends for enzymes to access and
• Breaking of a chemical bond 2) Colour change blue to red
• between two molecules hydrolyse starch into glucose, so glucose can be
• involving the use of a water molecule used more rapidly for respiration
Biochemical test to find non-reducing sugars
2) Large: doesn't diffuse across cell membrane
Glucose + glucose = maltose + water 1) do benedict's test ensuring a negative result
3) Coiled into a helix: compact so a lot can fit in a
Glucose + fructose = sucrose + water 2) Boil a fresh sample with acid small space
Glucose + galactose = lactose + water 3) Neutralise with alkali 4) Insoluble: so doesn't affect water potential
4) Heat with benedict's solution at 95 degrees
Monosaccharides Glycogen structure and function
Glucose has two isomers, alpha and beta 5) Colour change blue to red if positive result
1) coiled into a helix: compact, so a lot can fit into a
Alpha Beta: small space
Biochemical test to identify starch
2) Insoluble so doesn't affect water potential
1) add iodine in potassium iodide solution
3) More highly branched (animals need more ener-
The difference: the hydrogen and 2) Colour change orange to black if positive result gy) : larger surface area for enzymes etc…
hydroxyl group on carbon 1 are inverted
4) Polymer of (alpha) glucose so provides a respiratory
Drawing condensation and hydrolysis reactions
substrate
Beta glucose
• every other molecule is flipped (to ensure the bond be-
tween carbon 1 and 4)
Monomers, Polymers and carbohydrates
• position of the hydrogen and hydroxyl group on carbon
1 is inverted Biological molecules
Alpha = starch, glycogen Beta = cellulose
AQA A Level Biology
3.1 Biological Molecules
3.1.1 Monomers and Polymers
3.1.2 Carbohydrates
3.1.3 Lipids
3.1.4 Proteins and Enzymes
3.1.5 Nucleic Acids and DNA replication
3.1.6 ATP
3.1.7 Water
3.1.8 Inorganic Ions
, Monomer Smaller, soluble molecule from which Monosaccharides Monomers from which larger carbs are Cellulose structure and function
larger molecules are made made (glucose, fructose, galactose)
1) many beta glucose molecules joining together to
Polymer Molecules made from many similar form long, straight and unbranched chains of cel-
Disaccharides two monosaccharides joined together
monomers joined together lulose
Breaking and Forming Polymers Polysaccharides the condensation of many repeating 2) These chains are held together by many hydrogen
Condensation reaction: monosaccharides (e.g. starch, glycogen, bonds to form microfibrils
cellulose)
• the joining of two molecules together 3) These provide strength and rigidity to the cell
• by a chemical bond Biochemical Tests
• involving the elimination of a water mole- Starch structure and function
cule Biochemical test to find reducing sugars
Hydrolysis reaction: 1) Starch is branched: providing a higher surface area
1) + benedict's solution and heat to 95 degrees
as there are more ends for enzymes to access and
• Breaking of a chemical bond 2) Colour change blue to red
• between two molecules hydrolyse starch into glucose, so glucose can be
• involving the use of a water molecule used more rapidly for respiration
Biochemical test to find non-reducing sugars
2) Large: doesn't diffuse across cell membrane
Glucose + glucose = maltose + water 1) do benedict's test ensuring a negative result
3) Coiled into a helix: compact so a lot can fit in a
Glucose + fructose = sucrose + water 2) Boil a fresh sample with acid small space
Glucose + galactose = lactose + water 3) Neutralise with alkali 4) Insoluble: so doesn't affect water potential
4) Heat with benedict's solution at 95 degrees
Monosaccharides Glycogen structure and function
Glucose has two isomers, alpha and beta 5) Colour change blue to red if positive result
1) coiled into a helix: compact, so a lot can fit into a
Alpha Beta: small space
Biochemical test to identify starch
2) Insoluble so doesn't affect water potential
1) add iodine in potassium iodide solution
3) More highly branched (animals need more ener-
The difference: the hydrogen and 2) Colour change orange to black if positive result gy) : larger surface area for enzymes etc…
hydroxyl group on carbon 1 are inverted
4) Polymer of (alpha) glucose so provides a respiratory
Drawing condensation and hydrolysis reactions
substrate
Beta glucose
• every other molecule is flipped (to ensure the bond be-
tween carbon 1 and 4)
Monomers, Polymers and carbohydrates
• position of the hydrogen and hydroxyl group on carbon
1 is inverted Biological molecules
Alpha = starch, glycogen Beta = cellulose
