3.1.8 Inorganic ions Flashcards

• Ion


  an atom (or group of atoms) that has an electric charge
• Cation

  ion with a positive charge— e.g Na+ , Ca²+

  
• Anion


  ion with a negative charge— e.g Cl- , PO4³-

  
• Inorganic ion


  an ion that does not contain carbon— there are a few exceptions

  
• There are inorganic ions, in solution, in


  ● the cytoplasm of cells ● the body fluids of organisms
• Each ion has a specific role, depending on its properties, which


  determines whether it is found in high or low concentrations
• Inorganic ions

  ● Hydrogen ions (H+)● Iron ions (Fe²+/Fe³+)● Sodium ions (Na+)● Phosphate ions (PO4³-)● Calcium ions (Ca²+)
• Sodium ions (Na+)


  are involved in the co-transport of glucose and amino acids across membranes
• Why can't glucose and amino acids easily cross cell membranes ?


  ● are large molecules — molecule of glucose or an amino acid can be transported into cell across the cell - surface membrane alongside sodium ions Na + in co transport
• Hydrogen ions (H+)


  ● determine pH levels and acidity● the pH level is determined by the concentration of hydrogen ions in the environment in question ● enzyme controlled reactions are all affected by pH

  
• To calculate pH

  pH=-log10[H+]

  
• Iron ions (Fe²+/Fe³+)


  ● important part of haemoglobin ● are key to how oxygen is transported around the body by blood cells● the Fe²+ that binds to the oxygen in haemoglobin ● when oxygen is bound the Fe²+ ion temporarily becomes an Fe³+ ion— until oxygen is released

  
• Haemoglobin

  ● large globular protein ● carries oxygen around the body in the red blood cells● It's made up of four different polypeptide chains — each with an iron ion (Fe²+) in the centre

  
• Phosphate ions (PO4³-)


  ● essential component of nucleic acids DNA, RNA — Phosphodiester bonds are used to form the backbone of DNA and RNA● Used to Produce ATP● Key to phosphorylation — phosphate ions are added to other molecules— usually make them more reactive ● Found in phospholipids and form hydrophilic part of the phospholipid bilayer — cell membrane

  
• Calcium ions (Ca²+)


  ● essential in the movement of organisms● stimulates muscle contraction● activates many enzymes● regulate protein channels● form blood clots
• Ca²+ are essential in the movement of organisms


  In synapses they regulate the transmission of impulses from neurone to neurone
• Ca²+ stimulates muscle contraction


  ● When an impulse reaches a muscle fibre— Ca²+ is released from the sarcoplasmic reticulum● This Ca²+ binds to troponin C— removing the tropomyosin from myosin-binding sites on actin● This allows actin-myosin cross-bridges to form when the muscle fibre contracts
• Ca²+ activates many enzymes


  making these ions key regulators in many biological reactions
• Ca²+ can help regulate protein channels


  which affects the permeability of Cell membranes
• Ca²+ presence is necessary for

  the formation of blood clots— known as a clotting factor