The Composition of Carbohydrates

Forensic Chemistry > 2. Analysis of organic material can distinguish plant and animal material > The Composition of Carbohydrates >

Identify that carbohydrates are composed of carbon, hydrogen and oxygen according to the formula: Cx (H2O)y

Carbohydrates

  • often referred to as “Sugars”
  • one of the four biomolecules which are composed of carbon, hydrogen and oxygen, specifically polyhydroxyaldehydes, polyhydroxyketones and their derivatives.
  • follows the general formula, Cx(H2O)y
  • classified according to the number of sugar units and carbon atoms per sugar units

Monosaccharide

  • Simplest form of carbohydrate
  • The D-enantiomer is the naturally occurring form
  • Single glucose unit
  • Examples: Trioses (C3H6O3), Tetroses (C4H8O4), Pentoses (C5H10O5) and Hexoses (C6H12O6)
  • Categorized based on functional groups present
      • Aldoses
        • – contain an aldehyde group
        • Examples: Glyceraldehyde (Triose), Erythrose (Tetrose), Ribose (Pentose), Glucose (Hexose)
      • Ketoses
        • – contain a ketone group
        • – Examples: Dihydroxyacetone (Triose), Erythrulose (Tetrose), Ribulose (Pentose), Fructose (Hexose)

Disaccharide

  • Consists of 2 monosaccharide units which are connected by ether linkage or glycosidic bond
  • Can undergo hydrolysis into simpler sugars
  • Examples: Maltose, Sucrose (table sugar), Lactose

Oligosaccharide

  • Consists of 3 – 10 monosaccharide units which are connected by ether linkage or glycosidic bond
  • Examples: Raffinose, Stachyose, Verbascose

Polysaccharide

  • Consists of many monosaccharide units (> 10 glucose units) which are connected by ether linkage or glycosidic bond
  • Examples: Glycogen, Starch, Cellulose, Hemicellulose