inorganic ions

• on is an atom or group of atoms that has an electric charge
• an ion with a positive charge is called a cation
• • Na+
  • Ca2+
  • Cl-
  • PO4 3-
• an inorganic ion is one which doesn't contain carbon (although there are a few exceptions to this rule)
• there are inorganic ions in solution in:

  • the cytoplasm of cells
  • in the body fluids of organisms
• eachion has a specific role, depending on its properties. an ion's role determines whether it is found in high or low conc.
• iron ions in haemoglobin - haemoglobin is a large protein that carries oxygen around the body, in the red blood cells. It is made up of 4 different polypeptide chains, each with an iron ion (Fe2+) in the centre

  it is the Fe2+ that binds to the oxygen in haemoglobin - key component

  when oxygen is bound, the Fe2+ ion temporarily becomes an Fe3+ ion until oxygen is released
• Hydrogen ions - pH is calculated based on the con of H+ ions in the environment

  • the more H+ present the lower the pH - the more acidic the environ
  • enzyme controlled reactions are all affected by pH
• Sodium ions: glucose and amino acids need help crossing cell membranes

  molecule of glucose or an amino acid can be transported into a cell alongside Na+ ions - co-transport
• Phosphate ions: when a PO4 3- ion is attached to another molecule, it is known as a phosphate group.

  • DNA, RNA and ATP all contain phosphate groups
  • it is the bonds between phosphate groups that store energy in ATP
  • the phosphate groups in DNA and RNA allow nucleotides to join up to form the polynucleotides