A new cancer fighting agent was discovered in a rare tropical plant. In animals, the substance prevents mitosis by disrupting the formation of microtubules. If the microtubules are not working properly, which of the following is specifically affected?

A. Anaphase
B. The spindle fibers
C. formation of the centrioles
D. The S-phase is interphase

1.) During interphase, cells prepare to divide by making proteins and doubling chromasomal material.

2.) Centrioles form spindle fibers which attach to cetromeres at the cell.

3.) During anaphase, the spindle fibers pull chromosomes to opposite sides of the cell before telophase where the cytoplasm is divided and division is completed.

Since microtubules make up the spindle apparatus and allow for the attachment of the spindle fiber, the spindle fibers would be directly affected and anaphase can not be completed. So, I would go with answer choice B.

To determine which process is specifically affected when the microtubules are disrupted, let's break down the steps of cell division.

Mitosis is a cellular process that consists of several stages: prophase, metaphase, anaphase, and telophase. During metaphase, the chromosomes line up along the equator of the cell, while spindle fibers, which are made up of microtubules, attach to the chromosomes and help align them correctly. Anaphase occurs when the sister chromatids separate and move to opposite poles of the cell, a process that is driven by the shortening of the microtubules within the spindle fibers. Finally, telophase is when the chromosomes reach their respective poles and the cell begins to divide.

Given that the microtubules are disrupted by the cancer-fighting agent, it will most likely affect the process of anaphase (option A) since it is dependent on the proper functioning of microtubules within the spindle fibers. Therefore, the correct answer is:

A. Anaphase