Molecules
Disaccharides
Glucose + Glucose = Maltose
Glucose + Fructose = Sucrose
Glucose + Galactose = Lactose
Glycogen
• Used by animals to store excess glucose to be hydrolysed back into glucose when
animals require energy
• It has all the same properties as starch but is more branched.
Starch
Features for a good energy store:
Insoluble - doesn’t effect the water potential of the cell
• Amylopectin- highly branched and so allow enzymes to break the glycosidic bonds
for rapid release of glucose.
• Amylose - It's coiled and so compact so that a lot of glucose can be stored.
Testing for starch
1. Add iodine solution to the food samples and shake
2. Should turn from orange to blue-black for a positive result.
Cellulose
• Made up beta-glucose monomers joined via glycosidic bonds.
• They alternate 180° to keep the hydroxyl groups close enough to react.
• This allows for hydrogen bonds to form individual chains to make cell walls.
Testing for reducing sugars
1. Add benedict's solutión
2. Heat the mixture in a bath: Red= present
3. Use a colorimeter or filter and weight the precipitate
Testing for non- reducing sugars
1. Same test
2. Add hydrochloric acid and heat, to neutralise by adding sodium hydrogen carbonate
solution
, Lipids
Lipids and their roles
1. Energy supply - can be oxidised to provide energy to cells
2. Structural components - phospholipids in the cell membrane
3. waterproofing - they are insoluble
4. Insulation - lipids retain heat or act as electrical conductors.
Fatty acids
Saturated fatty acids - no double bonds. They have a higher melting point and are
usually solid at room temperature
Unsaturated fatty acids - have a double bond. They have a lower melting point and are
usually liquid at room temperature.
Testing for lipids
1. Add ethanol to your food sample
2. Add distilled water
3. A milky white precipitate will appear if present.
Triglycerides
Disaccharides
Glucose + Glucose = Maltose
Glucose + Fructose = Sucrose
Glucose + Galactose = Lactose
Glycogen
• Used by animals to store excess glucose to be hydrolysed back into glucose when
animals require energy
• It has all the same properties as starch but is more branched.
Starch
Features for a good energy store:
Insoluble - doesn’t effect the water potential of the cell
• Amylopectin- highly branched and so allow enzymes to break the glycosidic bonds
for rapid release of glucose.
• Amylose - It's coiled and so compact so that a lot of glucose can be stored.
Testing for starch
1. Add iodine solution to the food samples and shake
2. Should turn from orange to blue-black for a positive result.
Cellulose
• Made up beta-glucose monomers joined via glycosidic bonds.
• They alternate 180° to keep the hydroxyl groups close enough to react.
• This allows for hydrogen bonds to form individual chains to make cell walls.
Testing for reducing sugars
1. Add benedict's solutión
2. Heat the mixture in a bath: Red= present
3. Use a colorimeter or filter and weight the precipitate
Testing for non- reducing sugars
1. Same test
2. Add hydrochloric acid and heat, to neutralise by adding sodium hydrogen carbonate
solution
, Lipids
Lipids and their roles
1. Energy supply - can be oxidised to provide energy to cells
2. Structural components - phospholipids in the cell membrane
3. waterproofing - they are insoluble
4. Insulation - lipids retain heat or act as electrical conductors.
Fatty acids
Saturated fatty acids - no double bonds. They have a higher melting point and are
usually solid at room temperature
Unsaturated fatty acids - have a double bond. They have a lower melting point and are
usually liquid at room temperature.
Testing for lipids
1. Add ethanol to your food sample
2. Add distilled water
3. A milky white precipitate will appear if present.
Triglycerides
