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3.1 Biological molecules

  • All life on Earth shares a common chemistry. This provides indirect evidence for evolution.
  • Despite their great variety, the cells of all living organisms contain only a few groups of carbon-based compounds that interact in similar ways.
  • Carbohydrates are commonly used by cells as respiratory substrates. They also form structural components in plasma membranes and cell walls.
  • Lipids have many uses, including the bilayer of plasma membranes, certain hormones and as respiratory substrates.
  • Proteins form many cell structures. They are also important as enzymes, chemical messengers and components of the blood.
  • Nucleic acids carry the genetic code for the production of proteins. The genetic code is common to viruses and to all living organisms, providing evidence for evolution.
  • The most common component of cells is water; hence our search for life elsewhere in the universe involves a search for liquid water.

Source: AQA Spec

Included in this download

3.1.1Monomers and polymers
3.1.5Nucleic acids
3.1.8Inorganic ions