Final answer:
Chemotherapy drugs targeting microtubules interfere with the mitotic spindle function, causing errors in chromosome separation which can lead to cell cycle arrest and apoptosis, ultimately killing tumor cells.
Step-by-step explanation:
Chemotherapy drugs such as vincristine and colchicines target microtubules during cell division. Microtubules play a critical role in mitosis, particularly in the formation of the mitotic spindle, which is responsible for segregating chromosomes into daughter cells. By disrupting or stabilizing microtubule dynamics, these drugs prevent the mitotic spindle from functioning correctly, leading to errors in chromosome separation.
As a consequence, this can arrest the cell cycle and trigger apoptosis, the programmed cell death, ultimately causing tumor cells to die. In cases where disruptors of microtubule assembly are used, such as vinblastine, the prevention of spindle fiber formation leads to an inability of the cells to proceed past mitotic prophase. Additionally, drugs like Taxol stabilize microtubules to the extent that they cannot depolymerize, hindering completion of mitosis and causing cell death.