(a(i))[1]
Name the structure indicated by A on Fig. 1.1.
(a(ii))[1]
State the role of structure A.
(b)[2]
Haemoglobin is described as a globular protein. Explain why this protein is classified as globular.
(c)[2]
The gene $HBB$ codes for the $\beta$-globin polypeptide. State why a polypeptide such as $\beta$-globin is referred to as a polymer.
(d)[3]
A single base substitution in the DNA of the gene $HBB$ causes a change in the amino acid sequence of $\beta$-globin. In this sequence, one glutamic acid is replaced by valine. Outline the effects of this alteration in the amino acid sequence of $\beta$-globin on the structure and function of a haemoglobin molecule.
(e)[3]
Haemoglobin interacts with carbon dioxide and carbon monoxide. Outline haemoglobin’s role in carbon dioxide transport.