Natural Macromolecules

• Natural Macromolecules: Food’s main constituents are proteins, fats and carbohydrates.

• Proteins: Proteins contain the same linkages (amide links) as nylon, but with different units.
• Protein structure

  
• In digestion proteins are broken down into amino acids (hydrolysis).
• Fats are esters possessing the same linkage as Terylene (ester links) but with different units.
• Soap is a product of the hydrolysis of fat. It is done using sodium hydroxide (as opposed to acid, in digestion). The hydrolysis gives glycerol and the sodium salts of fatty acids. The salts are used as soaps.
• Complex carbohydrates: are a large number of joined sugar units (monosaccharide like glucose).
• The sugar units of carbohydrates are represented in this image

  
• Carbohydrate sugar molecules join together in a condensation polymerization

  
• In digestion, the hydrolysis (Decomposition of a chemical compound by reaction with water) of starch happens in the mouth by the enzyme amylase to make glucose
• Hydrolysis:

  • Starch → glucose
  • Proteins → amino acids
  • Fats → fatty acids and glycerol
• If hydrolysis is not complete, macromolecules are not completely broken down so you get a mixture of molecules of different sizes
• Identification of carbohydrates:

  • Chromatography can be used to identify products & substances
  • However, amino acids and sugars are colourless when dissolved in water, so a locating agent is used.
  • Substances can be identified using Rf values or by matching them with spots which are horizontal