The Bohr Effect

Question 1

What is the Bohr effect and, how does it change the oxygen dissociation curve?

Answer 1

• The Bohr effect is the effect of CO2 on the oxygen dissociation curve.
  —> due to the decrease in pH produced as carbonic acid is formed and an increase in H+ ions occurs.
  —> This causes the hydrogen and ionic bonds in the tertiary structure to break, changing the structure.
• An increase in CO2 concentration depresses the curve, ie. Shifts to the right, and haemoglobin releases more oxygen to repairing tissues.

Question 2

How does an increase in CO2 concentration affect affinity?

Answer 2

The higher the volume of oxygen produced, the lower the affinity between oxygen and haemoglobin, the higher the rate of oxygen dissociation as the change in tertiary structure due to the production of H+ ions, means that the haemoglobin group is more accessible.

Question 3

Why is the Bohr effect of physiological advantage to the body?

Answer 3

• During vigorous exercise, muscle cells respire more rapidly, producing more CO2. Therefore, more oxygen is dissociated from Hb, due to the lower affinity, for the increased rate of respiration.

Question 4

How does pH affect the oxygen dissociation curve?

Answer 4

• A lower pH causes the curve to shift to the right, as the affinity of haemoglobin to attract oxygen decreases, so the rate of oxygen dissociation increases,
  —> This is due to an increased CO2 concentration from increased respiration.

Question 5

How does temperature affect the oxygen dissociation curve?

Answer 5

• An increase in temperature depresses the curve, causes it to shift to the right, so that more O2 is released to cells.
  —> This is because temperature increases during increased respiration ( respiration releases heat).