Inorganic Ions

• An ion is an atom (or sometimes group of atoms) that have an electrical charge.
• What is an ion?

  An atom (or group of atoms) that have an electrical charge
• An ion that has a positive charge is known as a cation and an ion that has a negative charge is known as an anion.
• What is an ion with a positive charge called?

  A cation
• What is an ion with a negative charge called?

  An anion
• What charge does a cation have?

  Positive charge
• What charge does an anion have?

  Negative charge.
• Inorganic ions are molecules that don’t contain carbon atoms
• What atoms do inorganic ions not contain?

  Carbon
• What are inorganic ions?

  Ions that do not contain carbon and are not derived from living organisms.
• Inorganic ions play an important role in many essential cellular processes, they occur in solution in the cytoplasm and the body fluids of organisms, which maintain the optimum levels of each ion depending on the function of the cell.
• Because of optimum ion levels, some occur in high concentrations, while others are in very low concentrations as they would be toxic if concentrations were allowed to increase.
• Hydrogen ions are protons, and the concentration of these in solution determines the pH.
• There is an inverse relationship between pH value and the hydrogen ion concentration, as the more H+ ions that are present, the lower the pH and the fewer H+ ions that are present, the higher the pH.
• What is the relationship between the pH value and the hydrogen ion concentration?

  Inverse
• The more H+ ions present, the lower the pH (the more acidic the solution)
• The fewer H+ ions present, the higher the pH (the less acidic the solution)
• More H+ ions means that the pH is?

  Lower
• Less H+ ions means that the pH is?

  Higher
• The concentration of H+ ions are very important for enzyme-controlled reactions as they are all affected by pH.
• The maintenance of normal pH is essential for many of the metabolic processes that take place within cells.
• Changes in pH can affect enzyme structure, for example, abnormal levels of hydrogen ions can interact with the side chains of amino acids, changing the secondary and tertiary structures of the proteins that make up enzymes, which can cause them to denature.
• Different enzymes have different optimum pH ranges so some may be active at low pH while others work best at high pH.
• There are two versions of iron ions, which are known as its oxidation states:

  • Iron (II) ions, also known as ferrous ions (Fe2+)
  • Iron (III) ions, also known as ferric ions (Fe3+)
• What are the two oxidation states of iron?

  +2 and +3
• Iron ions are essential as they can bind to oxygen
• What molecule does iron ions bind to?

  Oxygen
• Haemoglobin is the large protein in red blood cells that is responsible for transporting oxygen around the body, it is made up of four polypeptide chains, each containing one Fe2+ ion.
• What is haemoglobin?


  The large protein in red blood cells that is responsible for transporting oxygen around the body
• What is haemoglobin made up of?

  Four polypeptide chains, each containing on Fe2+ ion
• The Fe2+ ion is a key component in haemoglobin as it binds to oxygen.
• Myoglobin in muscle functions in a similar way to haemoglobin as it is also an oxygen-binding protein, but it is only made up of one polypeptide chain, and thus one ferrous ion.
• Iron ions are essential as they are involved in the transfer of electrons during respiration and photosynthesis, so they are key to the biological generation of energy.
• Na+ is required for the transport of glucose and amino acids across cell-surface membranes (for example in the small intestine).
• What is Na+ used for?

  The transport of glucose and amino acids across cell-surface membranes and for the transmission of nerve impulses
• Na+ is required for the transmission of nerve impulses
• Glucose and amino acid molecules can only enter cells (through carrier proteins) alongside Na+ in a process known as co-transport.
• What is co-transport?

  The simultaneous transport of two substances across a cell membrane.
• Describe the role of Na+ in co-transport in the small intestine?

  Na+ is actively transported out of the epithelial cells that line the villi, causing its concentration inside the epithelial cells to be lower than the concentration in the small intestine. It now re-enters the cells 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.
• Phosphate ions attach to other molecules to form phosphate groups, which are an essential component of DNA, RNA and ATP