Testing for biological molecules 0.0 / 5 ? BiologyCells, tissues and organsGCSEOCR Created by: Molly BeverlyCreated on: 30-11-18 16:31 Non-reducing sugars If there aren’t any reducing sugar you can test for non reducing sugars Eg. Sucrose 1) Add hydrochloric acid 2) Heat in 75*c water bath 3) Add Sodium hydrogen carbonate (to neutralise) 4) Add Benedict’s reagent Positive result - coloured precipitate Negative result- stays blue 1 of 5 Reducing sugars Simple sugars made of one or two units eg. Glucose, Maltose 1) Add Benedict’s reagent (blue) 2) Put in 75*c water bath Positive result - coloured precipitate Higher concentration of sugar = further colour change Blue ~ Green ~ Yellow ~ Orange ~ Red 2 of 5 Starch Add iodine Positive result - colour change to Blue-Black colour Negative result- stays brown-orange 3 of 5 Protein 1) Add sodium hydroxide (to make solution alkaline) 2) Add copper (2) sulfate - blue Positive result - turns purple Negative result - stays blue 4 of 5 Lipids 1) Shake substance with Ethanol until it dissolves 2) Pour solution into water Positive result - milky emulsion will show up 5 of 5
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