Haemoglobin

Question 1

Describe the structure of haemoglobin

Answer 1

Quaternary structure made up of four polypeptide chains

Haem group contains an Fe2+ which can bind to an o2 molecule forming oxyhaemoglobin

Question 2

Define affinity

Answer 2

How easily haemoglobin binds and disassociates with oxygen

Question 3

Define partial pressure

Answer 3

The amount of particular gas in a mixture of gases or solution

Question 4

Why is the oxygen disassociation curve s shaped

Answer 4

Shallow curve bottom left - difficult for first o2 to bind to haemoglobin

Steeper in the middle - After first o2 binds it makes it easier

level off top right corner as haemoglobin has become fully saturated with oxygen

Question 5

Explain the Bohr shift

Answer 5

High conc of o2 - haemoglobin’s affinity for oxygen is lowered. This also decreases the saturation of haemoglobin so the curve shifts to the right

Question 6

Define cooperative binding

Answer 6

The binding of the first oxygen molecule results in a conformational change in the structure of the haemoglobin which makes it easier for each successive oxygen molecule to bind

Question 7

Three basic types of haemoglobin

Answer 7

1) Found in adult humans and many other species which live on land at sea level

2) Found in species that live in environments where environmental partial pressure of oxygen is low (high altitude or bottom of lakes)

Their haemoglobin dissociation curve is shifted to the left, their hb has a higher affinity for o2 and becomes fully saturated at lower ppo2 and therefore rapidly unloads when passing into tissues

3) A form with a curve shifted right and characteristic of species with a high metabolic rate

Hb has a lower affinity for oxygen and therefore dissociates more readily