Background to the Mitotic Cell Cycle
Mitotic can be defined as the type of eukaryotic cell division which creates two daughter cells with similar genetic elements as their parent cell. Cells behave almost the same way when they replicate and therefore, chromosomes replicate the same during the S phase to make sure that each daughter cell formed as a copy of the chromosome. However, the cell cycle is the series of stages or events which occur in a cell to cause its division and duplication of the cell DNA as well. However, the mitotic cell cycle is composed of metaphase, anaphase, prophase, Cytokinesis, and telophase. According to Larsen (2012, p.10), each of these phases is essential to the mitotic cell cycle, and at each stage, there is an event that occurs to facilitate the formation of daughter cells. For instance, at metaphase, the chromosome aligns themselves along the plate of metaphase of the spindle of the apparatus (Larsen, 2012, p. 12).
The Prophase stage is important to the cell cycle since it is the phase where the nuclear membrane breaks into pieces to form several small nucleolus and vesicles disintegrate. This is the phase whereby the mitotic spindle is formed for mitotic cell duplication which allows the mitotic to form two daughter cells. As stated by Lersen (2012), the cell cycle is essential because it prevents the division of the cell when it is not required to occur and it makes the division of the cell take place when it is needed. Therefore, cell division is essential for cells to grow and divide in multicellular organisms. Mitosis is important because it ensures that there is continuity of genetics by making sure that it creates a copy of DNA. It makes sure that the DNA is taken by carried by keeping the same number of chromosomes carried from one cell to another. Therefore, mitosis takes place in the skin, bones, and muscles, and immediately after the mitosis is complete a daughter cell is formed.
Studies have established that phases of the cell cycle can take different times to complete a complete cycle. Bettitta, Yigin, and Kiriaki (2015) noted that normally human cell has 24 hours of cycle time and the G1 phase is likely to take about eleven hours, the G2 phase will take about four (4) hours, the S phase eight (8) hours and M phase is also likely to take about one (1) hour. However, other types of cells can divide very rapidly though yeasts can go through all four stages of cell division. The most important thing is that the chromosome condenses during the mitotic cell cycle. The shape and the degree of compaction of chromosomes undergo several changes at the interphase immediately after it enters the mitosis which further condenses and individualizes to form a chromosome (Buttitta, Yiqin, & Kiriaki, 2015).
According to Antomin and Heinz (2016), once the chromosome is segregated by the spindle, the chromatin is reignited to reform its interphase structure fit or which can be competent for DNA transcription and replication. The molecular mechanism of mitosis then condenses and decadence to reform its interphase structure (Antonin & Heinz, 2016). It is proper to note that chromosome replicates during the S phase and therefore, it changes its structure when it condenses and decondense to regain a new shape.
Data Analysis
The experiment was completed in the laboratory using toluidine blue and dye that binds to DNA to give an accurate result. The experience result indicates that the cell of the untreated root has the lowest number of mitotic indexes. Though untreated root has the highest number of cells at the interphase and the cells continue to reduce as the cells of untreated root go through the cell cycle. From the result, it seems Organophosphate treated roots have the highest mitotic index of 7.9, followed by Baby treated roots with a mitotic index of 7.2. This means that the cell takes more time at the interphase stage compared to others like Metaphase and Telophase.
| Cell in | Cell in | Cell in | Cell in | Cell in | Mitotic | |
| Interphase | Prophase | Metaphase | Anaphase | Telophase | Index | |
| Data | 60 | 30 | 10 | 5 | 2 | 43.5 |
| Untreated root | 1882 | 49 | 24 | 31 | 11 | 5.8 |
| Manure Treated root | 1800 | 51 | 27 | 37 | 9 | 6.4 |
| Organophosphate treated roots | 1210 | 42 | 20 | 31 | 10 | 7.9 |
| Baby treated Roots | 1584 | 53 | 23 | 32 | 16 | 7.2 |
Table 1: Experiment result of cells cycle on various components
| Stages of Mitosis | Number of times in Eyepiece | Size of cell in each stage |
| Interphase | 14.5 | 14.5X0.01= 0.014 |
| Prophase | 0 | 0X0.001= 0 |
| Metaphase | 1 | 1X0.001 = 0.001 |
| Anaphase | 1 | 1X0.001 = 0.001 |
| Telophase | 2 | 2X0.001 = 0.002 |
Table 2: Size of cell in each stage of the cell cycle (x 100 magnification)
Data Interpretation
The present experience demonstrates the change in DNA at every stage of the cell cycle. Based on the observation of the five datasets, it is evident in the prophase cell cycle chromatin start to gather together and form chromosomes. The nuclear size of chromosomes and density are noticed and later disperse. It, therefore, means the interphase has gone nuclear membrane but in the prophase, the nuclear membrane is broken. A closer observation of the interphase and prophase from the test conducted reflects the fact that in interphase the mitosis of the cell several times. The experiment indicates that at metaphase the chromosomes have collected at the center of the cell. It is means the chromosomes are being prepared to move to the opposite side of the pole. This is why at metaphase there is a chromosome at the center of the cell and a closer look at t figure 3 of the metaphase will confirm.
However, the five datasets are compared using Fisher’s exacts test to confirm whether the proposed value is different from the values obtained from the experience. In this case, the fisher exact test is supposed to test the hypothesis that the duration of each cell cycle depends on the content of the cell. It is also supposed to confirm if the hypothesis is true that the cells which are divided mitotically are larger than normal cells, and check whether the higher the percentage of cells that are divided in one phase, the larger duration the cell takes on every phase. But the p-value is used to evaluate how best the data supports the hypothesis. It is used to compare the data collected and the accuracy of the data which, therefore, confirms the result obtained from the experience. According to Larsen (2012, p.12), the p-value is a probability that restricts certain principles in observation data, and therefore, in this experience the p-value is (0.05) which was used to conduct the test.
The experiment indicates that the size of the cell changes as the cycle continues. However, Table 2 indicates the size of cells in every phase. The result shows that the size of cells in every stage increases from interphase to telophase (Gogoi, Saurav, Sayak, & Mohammad, 2016, p. 32). It means the sizes of the cells which are undergoing interphase are usually tinny compared to the size of cells at other stages which are approximately 0.001. It is because chromosomes when in the cells are always uncoiled and not divided as well. And since the cell size of the chromosomes cannot be verified because at prophase there is no prophase cell.
The data collected is different from control data because the experiment discovered that the cell cycle time depends on the size of the cell and the content as well. It is discovered it is similar to control data because the number of cells in every dataset is different and the way it is reflected in the result from the experience. (Gogoi, Saurav, Sayak, & Mohammad, 2016, p. 21).
Based on the result obtained it is evident the three fertilizers catalyze the reaction and therefore, increase the mitosis of the cells. It is discovered that the manure-treated root has a mitotic index of 5.8, which is the lowest while the organophosphate-treated roots have a mitotic index of 7.9, the highest among the three fertilizers,s and Baby has a mitotic index of 7.2. This means that manure-treated root is not a fertilizer and therefore, it does not have an organic element. Organophosphates are the best fertilizer since it has the highest mitotic index and the highest number of cells at the interphase. The manure Treated roots are not working despite the fact that they had the highest number of cells, it still registers the lowest mitotic index and from the experience, it is clear the onion roots do not react quickly to manure compared to organophosphate and Babybio treated roots.
Bibliography
Antonin, W., & Heinz, N. 2016. Chromosome condensation and decondensation during
mitosis. https://www.sciencedirect.com/science/article/pii/S0955067416300059 , 2-45.
Buttitta, L., Yiqin, M., & Kiriaki, K. 2015. How the cell cycle impacts chromatin architecture
and influences cell fate. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315090/ , 2-35.
Gogoi, P., Saurav, D., Sayak, D., & Mohammad, Z. A. 2016. Effect of Organophosphorus
Insecticide, Malathion on the Division of Meristems of Allium cepa L. International Journal and Pure Applied , 2-34.
Larsen, M. V. 2012. Cell Cycle and Cell Division: CBS, DTU Systems Biology.
http://www.cbs.dtu.dk/courses/27008/F13/slides/Ch11_presentation.pdf, 1-34.
Appendix 1 Experiment result
