Biology AS revision

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Biological molecules are organic molecules made up primarily of carbon, hydrogen, nitrogen and oxygen. There are 3 groups of molecules; Carbohydrates, proteins and lipids.

CARBOHYDRATES

  • Carbohydrates contain carbon, hydrogen and oxygen.
  • There are 3 types of carbohydrates; monosaccharides, disaccharides and polysaccherides. 
  • Monosaccharide (monomers) and disaccharide (dimers) are simple sugars. Monosaccharides include glucose, fructose and ribose. Disaccharides include Maltose, sucrose and lactose.
  • Polysaccharides are complex sugars such as starch, glycogen and cellulose.
  • Their main functions are to act as a source of energy in both plants and animals, and to play a structural role in plant cell walls.

MONOSACCHARIDES

  • Monosaccharides are used for energy and building blocks for other carbohydrates.
  • (CH2O)n 
  • Triose = C3 H6 O3
  • Pentose = C5 H10 O5 (ribose)
  • Hexose = C6 H12 O6 (glucose + fructose)
  • Some compounds can have the same chemical formula but different structural formula.This is called structural isomerism. An example of this is glucose. in which it has alpha or beta structure.

DISACCHARIDES

  • This is when two monosaccharides are bonded together by a glycosidic bond, which is a condensation reaction due to the elimination of water. Hydrolysis is used to break this bond.
  • The 3 most…

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