Question

There are now many different types of chemotherapies used by oncologist to combat the cancer within their patients. Some of these drugs are known to allow microtubule assembly BUT prevent microtubules from disassembling. As a researcher you investigate one of these chemotherapies by putting it into a culture of actively dividing cells. In 24 hours you fix and stain the cells and observe them on a microscope. What phase of mitosis do you expect to find the majority of these cells in and why?

Answer 1

Chemotherapy drugs like vincristine and colchicine inhibit microtubule disassembly by binding to tubulin, causing cell cycle arrest at metaphase during mitosis. The chemotherapeutic agents prevent spindle fiber shortening and subsequent sister chromatid separation, which is necessary for cell division to proceed.

Step-by-step explanation:

Chemotherapy drugs like vincristine and colchicine work by disrupting the normal function of microtubules during cell division. These drugs target microtubules by binding to tubulin, which is essential for the assembly and disassembly of microtubules. As a result, microtubules can assemble but cannot disassemble.

When you treat actively dividing cells with these chemotherapy drugs, you can expect to see them arrest at metaphase during mitosis. This is because the microtubules of the mitotic spindle cannot depolymerize, which is a critical step for progressing beyond metaphase to anaphase. The spindle fibers are unable to shorten and pull apart the sister chromatids to opposite poles of the cell.

By fixing and staining cells after treatment with these drugs, the cells likely captured in the majority would be in metaphase, where they are unable to complete mitosis due to the stabilized microtubules preventing the next phase of cell division.