Biological molecules (AQA AS Biology) PART 8 of 8 TOPICS

Inorganic ions:

Inorganic ions can either occur in high concentrations or low concentrations in the cytoplasm and body fluids.

H⁺ ions regulate how acidic a solution is where the more protons there are the more acidic a solution is.

Iron ions in haemoglobin bind to oxygen so that oxygen can be released to respiring cells (more on this in a later module in AS, check it out).

Sodium ions are used for the transfer of glucose to the cells by co transport:

• Sodium ions are pumped out of the cell into the blood by the sodium-potassium pump powered by Pi. (Potassium ions come in from the blood also but have no relevance to co transport)
• This causes the concentration of sodium ions in the cell to drop so the sodium ions from the lumen comes into the cell down its concentration gradient along with glucose going up its concentration gradient by facilitated diffusion through the coupled transport protein. This is called a symport.

NB: Sodium-potassium pump is on the opposite side to the coupled transport protein of the cell when glucose is transported which is described above. When it comes to amino acids the sodium-potassium pump is on the same side to the coupled transport protein of the cell. Sodium ions are actively transported into the ileum from the epithelial cells instead of into the blood. Then the sodium ions diffuse back in along with amino acids into the epithelial cells.

Phosphate ions are used to make nucleotides, ATP and making bones strong by reacting with calcium to make calcium phosphate [Ca₃(PO₄)₂]

] That is all that you need to know about inorganic ions [