1.8 Inorganic ions

• Where are inorganic ions found in the body?

  In solution in cytoplasm and body fluid, some in high concentrations and others in very low concentrations.
• Describe the role of hydrogen, iron?

  Hydrogen ions (H + )

  ● Maintain pH levels in the body → high conc. = acidic / low pH

  ● Affects enzyme rate of reaction as can cause enzymes to denature (topic 1.4.2)

  Iron ions (Fe 2+ )

  ● Component of haem group of haemoglobin

  ● Allowing oxygen to bind / associate for transport as oxyhaemoglobin (topic 3.4.1)
• Sodium ions (Na + )

  1. Involved in co-transport of glucose / amino acids into cells (topic 2.3 / 3.3)
  2. 2. Involved in action potentials in neurons (topic 6.2) 3. Affects water potential of cells / osmosis (topic 2.3)
• Phosphate ions (PO4 3- )

  1. Component of nucleotides, allowing phosphodiester bonds to form in DNA / RNA
  2. Component of ATP, allowing energy release
  3. Phosphorylates other compounds making them more reactive (topic 1.6)
  4. Hydrophilic part of phospholipids, allowing a bilayer to form (topic 1.3 / 2.3)
• Exam insight: common mistakes ❌-(1/2)

  ❌-*Naming an ion as an element.*

  ✅-For example, you need to say ‘iron ions’ and not just ‘iron’.
• Exam insight: common mistakes ❌-(2/2)

  ❌-“ATP hydrolysis creates energy.”

  ✅-Energy cannot be created - only transferred / released