Unit 4: Biological Molecules

Simple sugars

Basic unit of starch and glycogen

Fatty acid and glycerol

Basic units of fats and oils

Amino acids

Basic units of proteins

Starch

Add a few drops of iodine. Positive result: blue black color

Reducing sugars/ Glucose

Add Benedict’s Reagent, then mixture is heated in water bath for 2-3 minutes. Positive result: brick-red precipitate, negative result: remains blue

Proteins

Add few drops of Biuret Reagent, positive color: purple color

Fats

Emulsion test; ethanol is added to the mixture and this is poured into a test tube with an equal amount of distilled water; positive results milky white emulsion

Vitamin C

Decolonization of DCPIP shows that vitamin C is probably present

Structure of DNA

Two strands of Chromosomes together to form a double helix with each strand containing chemicals called bases (A, T, C, G)