Organic compounds - Carbohydrates

Monosaccharides (single sugar)

• Energy source for cells.
• Formula typically n (CH₂O). Where n=integer.
• Single bond hydroxyl on each C, except one double bond to a carbonyl.
• Characterized by number of C atoms in ring (3 to 7).
• Common sugars:
  • glyceraldehyde C₃H₆O₃     (triose)
  • ribose C₅H₁₀O₅     (pentose)
  • glucose C₆H₁₂O₆     (hexose)
  • fructose C₆H₁₂O₆     (hexose)
  • galactose C₆H₁₂O₆     (hexose)

Disaccharides (two sugars)

• Dehydration synthesis: -OH from one sugar and H from another form
  H₂O and covalently bond sugars.
• Common Disaccharides:
  • sucrose : glucose + fructose
  • lactose : glucose + galactose
  • maltose : glucose + glucose

Polysaccharides (many sugars)

• Can be 1 x 10⁶ monosaccharides long.
• Long chains can cross-link using hydrogen bonds.
• Storage uses:
  • plants : starch (glucose polysaccharide).
  • animals : glycogen (highly cross-linked glucose polysaccharide).
• Structural uses:
  • plants : cellulose (glucose polysaccharide).
    Created from glucose isomer with bonds most organism can't break.
    Most abundant organic compound on Earth.
  • animals (arthropods) : chitin (polysaccharide of glucose + amino group).