1.8 Inorganic Ions

Question 1

Describe the role of iron ions in cells.

Answer 1

• important component of haemoglobin
• haemoglobin binds to oxygen and transports it around the body

Question 2

Describe the role of sodium ions in cells.

Answer 2

• involved in the co-transport of glucose/amino acids into cells
• sodium is moved out by AT via the Na-K pump
• this creates a Na concentration gradient which glucose and amino acids use to enter the cells
• Na ions also affect the water potential of cells

Question 3

Describe the role of phosphate ions in cells.

Answer 3

• phosphate ions affect the water potential of cells
• phosphate ions attach to other molecules to form phosphate groups, which are an essential component of DNA, RNA and ATP
• joins nucleotides by phosphodiester bonds in the backbone of DNA/RNA
• used to produce ATP
• phosphorylates other compounds often making them more reactive
• makes up the hydrophilic component of the phospholipid bilayer

Question 4

Describe the role of hydrogen ions in relation to pH.

Answer 4

• the concentration of H+ in a solution determines its pH
• inverse relationship between the pH value and the hydrogen ion concentration
• the more H+ ions present, the lower the pH (the more acidic)
• the fewer H+ ions present, the higher the pH (the more alkaline)
• very important for enzyme-controlled reactions (all affected by pH)