Chapter 10:The variety of life, biochemical basis and cellular organisation

Haemoglobin 

• Occurs in red blood cells, vital role of oxygen transport 
• Protein with quaternary structure as it is made from four polpeptide chains
• Oxygen carried as oxyhaemoglobin in red blood cells
• Behaviour illustrated by oxygen dissociation curves 

There are two key features of oxygen dissociation curves: 

1) At the high oxygen concentrations found in the lungs, where the curve is level, haemoglobin becomes almost fully saturated with oxygen 

2) At the low oxygen concentration found in the tissues, where the curve is steep, oxyhaemoglobin dissociates, releasing much of its oxygen. In this part of the curve, a small drop in oxygen concentration can cause a relatively large change in the percentage saturation of the haemoglobin, which releases large amounts of oxygen. 

At a higher concentration of carbon dioxide, the curve is shifted to the right. This is because carbon dioxide is an acidic gas that lowers the affinity of haemoglobin for oxygen. This is knwon as the Bohr effect. The signifance of this is seen in metabolically active tissues, such as muscles…