Haemoglobin

Question 1

Structure of haemoglobin

Answer 1

4 polypeptide chains each containing a haem prosthetic group (iron)
2 alpha and 2 beta chains

Question 2

Haem structure

Answer 2

Iron found in haem
Each Fe2+ binds with 1O2
1 haemoglobin binds with 4 O2 molecules
Different shapes will affect affinity in other organisms

Question 3

Process of disassociation curve

Answer 3

Hard for first O2 molecule to bind as haem groups are in the middle of the haemoglobin molecule
Second and third O2 bind easier as first binding has caused a conformational change in haemoglobin molecule, tertiary structure altered
4th Oxygen does not bind as easily as hard to reach 4th binding site, less chance of collision

Question 4

Why do different haemoglobin have different affinities for O2

Answer 4

Different haemoglobin have slightly different amino acid sequences. Therefore, their tertiary and quaternary structures differ and so have different oxygen binding properties

Question 5

Effects of high CO2 concentration of haemoglobin

Answer 5

In rapidly respiring tissue, the conc of CO2 is high
This decreases the pH of the respiring tissue, changing the shape of the haemoglobin
The haemoglobin as a result more readily dissociates from the O2 into the muscle cells
This causes the oxyhaemglobin dissociation curve to shift right

Question 6

Effect of Low conc of CO2 on haemoglobin

Answer 6

As gas exchange surface, low concentration of CO2 due to excretion by expiration.
Affinity of haemoglobin to O2 increased
High concentration of O2 at lungs
O2 more readily loaded by haemoglobin
Shifts curve to the left