Inorganic Ions

• Cations have a positive charge. Anions have a negative charge.
• Inorganic ions generally do not contain carbon.
• Hydrogen ions

  • pH is a measure of the H+ ions in a solution.
  • A logarithmic scale is used.
  • The more H+ ions, the more acidic the solution.
  • All enzyme controlled reactions are affected by pH.
• Iron (Fe 2+) ions

  • Haemoglobin is a large protein molecule with four subunits found in erythrocytes (red blood cells). Each subunit has a polypeptide chain and a non-protein haem group containing a single iron atom in the form of Fe 2+.
  • The iron ion can attract and bind with an oxygen molecule.
  • The haem group has a high affinity for oxygen. Each can hold one oxygen molecule (so 4 molecules per haemoglobin).
• Sodium ions

  • Sodium ions are used to co-transport glucose and amino acids into cells.
  • Co-transporters are specialised intrinsic proteins which span the phospholipid bilayer.
  • The Na+ ion is transferred across the membrane by the protein whilst linked with the amino acid or glucose molecule.
• Phosphate ion (PO4 3-)

  • DNA, RNA and ATP all contain phosphate groups.
  • The phosphate groups in ATP store energy.
  • The phosphate groups in DNA and RNA allow phosphodiester bonds to form between nucleotides, forming polynucleotides.