Mass transport 3.3.4

Question 1

Describe the structure of haemoglobin?

Answer 1

A globular protein with a quaternary structure, consisting of 4 polypeptide chains, each carrying a haem group and is water soluble

Question 2

What is the role of haemoglobin in red blood cells?

Answer 2

Each haem group binds to a molecule of oxygen and carries it to respiring tissues

Question 3

Give three factors that affect the binding of haemoglobin to oxygen

Answer 3

• partial pressure of oxygen
• partial pressure of carbon dioxide
• saturation of haemoglobin with oxygen

Question 4

How does ppO2 affect oxygen binding to haemoglobin?

Answer 4

As ppO2 increases the affinity of haemoglobin for oxygen increases. When ppO2 is low oxygen disassociates from oxyhaemoglobin

Question 5

How does ppCO2 affect the binding of oxygen t haemoglobin?

Answer 5

As ppCO2 increases then the acidity increases causing the haemoglobin to change shape. The affinity of haemoglobin for oxygen decreases and oxygen is more readily uploaded into respiring tissue, this is known as the Bohr effect

Question 6

How does saturation of oxygen effect oxygen binding with haemoglobin?

Answer 6

It is difficult for the first molecule of oxygen to bind but once it does it makes it easier for the second and then third to bind because the shape of haemoglobin is altered slightly, this is known as positive cooperativity. It is then slightly more difficult for the last molecule to bind as there is only one binding site available.