Carbohydrates

• A monosaccharide is a carbohydrate monomer
• The monosaccharides consist of alpha and beta glucose, galactose and fructose
• The disaccharides are sucrose, maltose and lactose
• lactose is made from galactose and alpha glucose
• sucrose is non reducing and made from fructose and alpha glucose
• Maltose is made from two alpha glucose monomers
• The three polysaccharides are starch, glycogen and cellulose
• Cellulose is a structural carbohydrate consisting of many beta glucose monomers joined with 1-4 and 1-6 carbon bonds
• To form a straight chain, beta glucose molecules flip 180 degrees every other molecule, this ensures each chain is parallel to allow for many hydrogen bonds to form providing strength
• Starch is a storage polysaccharide used in plants consisting of helical amylose and branched amylopectin - this keeps the molecule compact for storage
• Starch is large to prevent it from leaving the cell
• Starch is insoluble to prevent changes to water potential
• Glycogen is a storage carbohydrate in animals designed for rapid release due to its heavily branched nature - it is made from many alpha glucose monomers
• Glycogen is large and insoluble preventing it from leaving and changing the cellular water potential
• Condensation reactions between carbohydrates release a water molecule and form a glycosidic bond
• To test for sucrose, a negative benedicts test is needed, add hydrochloric acid to break glycosidic bonds between alpha glucose and fructose, add sodium hydrogen carbonate to neutralise the solution, repeat the benedicts test
• The most positive benedicts test is red, the least positive test result is blue
• A benedicts test and solution must be heated to 100 degrees
• C1 V1 + C2 V2 : C1 is the concentration of stock solution, V1 is the volume of stock solution, C2 is the concentration of the dilution, V2 is the volume of the dilution