In Chapter 1 it was noted that microtubules are tiny tubes made of protein subunits which join together and the protein is called tubulin. Colchicine is a natural chemical which binds to tubulin molecules, thus preventing the formation of microtubules.

a. Why should the binding of colchicine to tubulin molecules interfere with the formation of microtubules?

b. What structure or structures involved in mitosis are made of microtubules?

c. When cells treated with colchicine are observed, the dividing cells are all seen to be in the same stage of mitosis. Suggest with reasons the identity of this stage.