Biochemistry Practical Report: The Effect Of Colchicine Against Mitosis

In this practical we were investigating the effect of colchicine against mitosis. We counted the number of cells found in each stage of mitosis (including only prophase, metaphase, anaphase and telophase) for both untreated and treated cells.

Hypothesis: The treatment of the root tips with colchicine will reduce mitosis.

Null hypothesis: Colchicine treatment will have no significant effect on mitosis within the root tip cells.

The results I obtained from this practical provide insufficient evidence to support either the alternate or the null hypothesis. This is because while undergoing the investigation it was very difficult to find cells in any of the four phases. However, the class results showed far more reliable data. In the class results the ratio of cells in prophase to those in any other mitotic phase is higher for the treated cells. Many more cells were found in prophase for the treated cells than the untreated cells, and far fewer cells were found in any other mitotic phase in the treated cells than the untreated cells. This indicates that the treatment of colchicine is causing mitosis to slow or is preventing mitosis entirely in some cells. Therefore, there is evidence to suggest that colchicine is an inhibitor cell division.

In part 2 of this practical we were investigating the difference between the number of chromosomes present during metaphase in diploid and aneuploid cells.

Diploid cells are the most common form of cell found in the body. They contain two sets of chromosomes, one set obtained from each parent. A normal diploid cell has 46 chromosomes. These cells undergo cell division in the body in order to replace and produce new cells. An example of this is skin cells. Skin cells constantly need to be replaced therefore mitosis of skin cells is vital. Haploid cells contain half as much genetic information as diploid cells as they contain only one set of chromosomes. Examples of haploid cells are sperm cells and egg cells – gametes. Gametes divide by meiosis and contain only 23 chromosomes. Gametes contain one set of chromosomes so that when fusion occurs between an egg and a sperm cell to produce a zygote, the new cell contains two sets -one from each parent. This cell is now diploid and will go on to divide by mitosis producing identical clones of itself. Both diploid and haploid cells are normal cell types. Aneuploid cells contain an abnormal number of chromosomes. Normal cells are either haploid or diploid containing either 23 or 46 chromosomes. An aneuploid cell has a different number of chromosomes. Aneuploidy in cells can cause serious problems and often the person with the aneuploid cells is unable to function in the same way as those with normal a normal chromosome count in their cells. As a result, aneuploidy can cause major disabilities such as down syndrome or even be fatal.

The results I obtained show that the aneuploid cells do not contain a normal number of chromosomes at metaphase. However, our results contain inconsistencies and an anomalous result for the third karyotype we tested in the diploid cells. For this reason, it is difficult to draw conclusions about the number of chromosomes present in aneuploid vs diploid cells at metaphase. This is due to difficulties in accurately counting the number of chromosomes visible as the magnification and resolution we used made some of the chromosomes indistinct.