B3: biological molecules

Carbohydrates, proteins, lipids

• all contain carbon

Carbohydrates: carbon, oxygen, hydrogen (CHO)

• long chains of simple sugars

• glucose

  • 2 glucose → maltose

  • lots of glucose: starch/glucose/cellulose

protein: carbon, oxygen, hydrogen, nitrogen (CHON)

• long chains of amino acids

lipid: carbon, oxygen, hydorgen (CHO)

• 1 glycerol, 3 fatty acids

• fats (solid at room temp)

• oils (liquids at room temp)

Reducing sugar (glucose)

• Add benedict’s solution

• heat in water bath

• positive: blue → orange/brick red

Starch

• add drops of Iodine solution

• positive: orange-brown → blue black

Protein

• drops of biuret solution

• positive: blue → violet/purple

Lipids

• mix with ethanol with food sample and cold water

• positive: cloudy emulsion