Inorganic Ions

• What is an ion?

  an atom (or group of atoms) that has an electric charge
• What is a cation?

  an ion with a positive charge
• What is an anion?

  an ion with a negative charge
• what is an inorganic ion?

  an ion that doesn't contain carbon (are a few exceptions)

  Inorganic ions play an important role in many essential cellular processes

  Some occur in high concentrations and others in very low concentrations
• Where are some places that inorganic ions can be found ?

  • solution
  • cytoplasms of cells
  • body fluids of organisms
• How are iron ions important in haemoglobin?

  • haemoglobin is a large protein that carries oxygen around the body in the red blood cells
  • its made up of 4 different polypeptide chains - each with an iron ion(Fe2+) in the centre
  • Its the Fe2+ that actually binds to the oxygen in haemoglobin - key component
  • when oxygen is bound , the Fe2+ ion temporarily becomes an Fe3+ ion, until oxygen is released
• What do hydrogen ions determine ?

  • pH is calculated based on the concentration of hydrogen ions (H+) in the environment
  • The more H+ present, the lower the pH (and the more acidic the environment)
  • The fewer H+ ions present, the higher the pH (the more alkaline the solution)
  • Enzyme-controlled reactions are all affected by pH
• What do sodium ions (Na+) do ?

  • Help transport glucose and amino acids across membranes (e.g. in the small intestine)
  • glucose and amino acids need a bit of help crossing cell membranes
  • a molecule of glucose or an amino acid can be transported into a cell (across the cell-surface membrane) alongside sodium ions (Na+)(through carrier proteins)- known as co-transport
• How are Phosphate ions important ?

  • are an essential component of ATP and DNA
  • when a phosphate ion is attached to another molecule, its known as a phosphate group
  • DNA,RNA & ATP all contain phosphate groups
  • Its 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
  • Phosphates are also found in phospholipids, which are key components of the phospholipid bilayer of cell membranes
• sodium ions p2 = describe the process they are used in the small intestine (co-transport)

  • First, Na+ is actively transported out of the epithelial cells that line the villi
  • The Na+ concentration inside the epithelial cells is now lower than the Na+ concentration in the lumen of the small intestine
  • Na+ now re-enters the cells (moving down the concentration gradient) through co-transport proteins on the surface membrane of the epithelial cells, allowing glucose and amino acids to enter at the same time