Question

Assume that a drug is developed that prevents the prometaphase stage of mitosis from occurring but does not prevent any stages of mitosis prior to prometaphase from occurring nor does it interfere with any part of interphase. What will be the immediate consequence of this drug?

1. DNA replication will not happen so that each chromosome will contain a single DNA molecule.
2. The chromosomes will not be able to condense.
3. Sister chromatids will not be present.
4. Spindle microtubules will not be able to attach to chromatids.
5. Sister chromatids will separate and move toward opposite poles prematurely.

Answer 1

4. Spindle microtubules will not be able to attach to chromatids

Step-by-step explanation:

Mitosis is a kind of cell division that results in identical daughter cells. Prior to the actual division (mitotic phase), the cell undergoes certain preliminary stages that aims to prepare it for division. This stage is called INTERPHASE. What occurs mainly during interphase, specifically during S-phase is the replication of the genetic material (DNA). The DNA content becomes doubled forming sister chromatids, which is a replicated chromosome. When this and other structural adjustments occur in the Interphase, the cell enters mitosis proper.

The first stage of mitosis is Prophase, where the DNA found as Chromatin material condenses to a visible X-shaped structure called CHROMOSOME. The next stage after Prophase and before metaphase is the prometaphase stage. Ideally, proteinous structures called Kinetochores are formed from the chromosomes and centrosomes from each end of the cell form spindle microtubules to attach to the kinetochores of each chromosome.

In a case where a prometaphase inhibitory drug is used on the cell, every other process before prometaphase occurs normally but the spindle microtubules will not be able to attach to the kinetochores of each chromosome (sister chromatid) making aligning them to the equator (metaphase plate) difficult or impossible.