LO6: Haemoglobin

What is haemoglobin composed of?

Four polypeptide chains — 2 alpha (α) chains and 2 beta (β) chains — each bound to a heme pigment.

What is the heme pigment’s key component?

A single iron (Fe) atom at the center of each heme group.

How many oxygen molecules can one haemoglobin molecule carry?

Up to 4 oxygen molecules (one per heme group).

How many haemoglobin molecules are in one red blood cell (RBC)?

Approximately 250 million haemoglobin molecules per RBC.

What is the primary function of haemoglobin?

To bind oxygen in the lungs and transport it to body tissues; it also helps carry some carbon dioxide (CO2) back to the lungs.

What property allows haemoglobin to pick up and release oxygen efficiently?

Reversible binding — haemoglobin binds oxygen where oxygen concentration is high and releases it where it is low.

How does haemoglobin contribute to blood colour?

Oxygenated haemoglobin gives bright red colour; deoxygenated haemoglobin is darker red.