a. Rearrange the following statements to produce a flow diagram to show how monoclonal antibodies are produced.

1. Hybridoma cells cultured

2. Mouse injected with antigen

3. Mouse plasma cells fused with cancer cells

4. Hybridoma cells making appropriate antibody cloned

5. Mouse B-lymphocytes that recognise the antigen become plasma cells

b. A monoclonal antibody has been produced that binds to a glycoprotein called tumour-associated antigen (TAG). TAG is found in ovarian cancer and colon cancer cells.

The antibody is labelled with the radioactive isotope indium-111, (111In). This isotope emits low-energy gamma rays that can pass through soft tissues of the body. The half-life of indium-111 is 2.8 days.

i. Explain how this monoclonal antibody can be used in the diagnosis of cancer.

ii. Suggest why indium-111 is a suitable radioactive label for this diagnostic antibody.

iii. Suggest how the antibody could be modified in order to treat a cancer.