Interphase

How Much Time Do Cancerous and Apical Meristem Cells Spend in Each Mitotic Stage in Comparison to Normal Animal Cells? Introduction The cell cycle is the cycle of growth by which eukaryotic cells asexually reproduce by replicating themselves. The process of replicating a cell's DNA and dividing into two cells is called mitosis. Mitosis consists of five main stages. These include interphase, prophase, metaphase, anaphase, and telophase. In order to ensure proper cell replication, cells have crucial checkpoints in which they determine whether the proper tasks have been completed correctly and if the cell should continue through the cycle. There are three main checkpoints. These include the G1, G2, and Mphase checkpoints. During G1 (gap 1), a cell grows larger and synthesizes organelles. After this section of the cell cycle, a checkpoint is installed to make sure the cell should continue to replicate, as interphase follows this gap. In interphase, each chromatid replicates itself, which creates chromosomes, or a pair chromatid that carry the same genetic information. The replication of all of the DNA contained in a cell must be done efficiently and thus takes time; consequently, a cell spends its most amount of time in interphase. Since this task requires an immense amount of energy from the cell, a checkpoint is needed to ensure that it is worth spending energy on. Next, a cell goes through the Sphase, or synthesis of DNA. This phase is the interphase stage of mitosis. Then comes G2, where the cell grows further and gets ready to duplicate its centrioles/ microtubules. After these two phases are complete, another checkpoint is installed before proceeding to physically split the cell, because once you pass into Mphase (mitosis), you cannot turn back and cease splitting. This checkpoint is there to make sure that the DNA and centrioles were properly duplicated. After Mphase is complete and the cell has successfully split, a last checkpoint is installed. This checkpoint serves as a barrier in which a cell can either continue to divide or stop dividing. This is important because cells need to stop diving at one point or else tumors and or excess cells will become present, which is harmful and potentially fatal to the body. In cancerous cells, the checkpoints are ignored and a cell goes through the whole cell cycle rapidly in order to speed up its pace of reproduction. They will eventually form tumors and metastasize unless addressed at an early stage. The ignorance of checkpoints causes cancerous cells to be potentially fatal. Hypothesis It was hypothesized that onion's apical meristem cells will be in interphase for comparatively less time than normal cells because they are dividing more often in order to speed up cell division so that the roots can grow. It was also hypothesized that cancerous cells will spend comparatively less time in interphase than normal animal cells because they ignore the checkpoints in the cell cycle and spread by dividing, Therefore, they will spend less time in interphase to accommodate the need to divide faster. Methods First, a slide containing a snapshot of the cells in the apical meristem was observed under the microscope. Then, the amount of cells in each mitotic stage was counted in order to calculate the approximate number of minutes a cell spends in each specific stage. Therefore, this is a quantitative experiment because it dealt with a numerical amount, that is, how many minutes does a cell spend in each mitotic stage. Data This chart shows the number of cells in each mitotic stage in an onion's apical meristem cells. * This chart shows the number of cells in each mitotic stage in normal cells. * This chart shows the number of cells in each mitotic stage in cancerous cells. * Analysis The slides used to obtain the data was a snapshot of the cell's activity at one given moment. This data was used in the calculations to discover the number of minutes a specific kind of cell spends in each stage as it is proportional to the number of cells in each stage. The equation used to determine the number of minutes each type cell spends in each phase was: Number of cells in a specific phase x total amount of time specific type = time spent in Total number of cells counted of cell spends in one cell cycle specific phase ____ = divided by x = multiplied by An onion's apical meristem cells spend 720 minutes in one cell cycle. The total number of cells counted was 289. Therefore, the specific equation used to determine the number of minutes spent in each stage was: Number of cells in a specific phase x 720 = time spent in specific phase 289 cells A normal cell spends 625 minutes in one cell cycle. The total number of cells counted was 500. Therefore, the specific equation used to determine the number of minutes spent in each stage was: Number of cells in a specific phase x 625 = time spent in specific phase 500 cells A cancerous cell spends 448 minutes in one cell cycle. The total number of cells counted was 500. Therefore, the specific equation used to determine the number of minutes spent in each stage was: Number of cells in a specific phase x 448 = time spent in specific phase 500 cells * * * The following graph supplies the data needed to determine a conclusion to the hypothesis * Conclusion The data collected supported the hypothesis because it showed that both the onion's apical meristem cells and the cancerous cells spent a lower percentage of time in interphase than normal animal cells. While a normal animal cell spends 88% of its time