• There is much variety of life within and between organisms but the biochemical basis of life is similar for all living things
• The key molecules that are required to build structures that enable organisms to function are:
  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic Acids
  • Water

   

• Monomers?are the smaller units from which larger molecules are made
• Polymers?are molecules made from a large number of monomers joined together in a chain

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The key biological molecules for living organisms

• Carbohydrates, proteins, lipids and nucleic acids contain the elements?carbon?(C) and?hydrogen?(H) making them?organic compounds
• Carbon atoms are key to the organic compounds because:
  • Each carbon atom can form?four?covalent bonds?– this makes the compounds very stable (as covalent bonds are so strong they require a large input of energy to break them)
  • Carbon atoms can form covalent bonds with oxygen, nitrogen and sulfur
  • Carbon atoms can bond to form?straight chains,?branched?chains?or?rings

   

• Carbon compounds can form small single subunits?(monomers)?that bond with many repeating subunits to form large molecules?(polymers)?by a process called?polymerisation
• Macromolecules?are very large molecules
  • That contain 1000 or more atoms therefore having a?high molecular mass
  • Polymers can be macromolecules, however?not?all?macromolecules are polymers as the subunits of polymers have to be the?same?repeating units

   

Carbohydrates

• Carbohydrates are one of the main carbon-based compounds in living organisms
• All molecules in this group contain?C,?H?and?O
• As?H?and?O?atoms are always present in the?ratio?of?2:1?(eg. water H₂O, which is where ‘hydrate’ comes from) they can be represented by the formula?C_x?(H₂O)_y
• The three types of carbohydrates are?monosaccharides,?disaccharides?and?polysaccharides

Types of Carbohydrates Table