July 21, 2005
In the lab exercise related to Mitosis, we view various slides containing cells undergoing Mitosis. We viewed 2 different specimens; a slide of an onion root tip and a slide of Ascaris eggs. Some of the cells are at different phases of Mitosis (Interphase, Prophase, Metaphase, Anaphase, Telophase). We viewed it under HPO and LPO. Chromosomes were visible in both the LPO and the HPO although the spindle fibers were not very visible because of limitations in the light microscope. The exercise was successful because we were able to see different cells at different phases of Mitosis. We were able to discover the differences between each reaction and why Mitosis is divided into different phases. We were also able to label some of the parts in the cells undergoing mitosis. Overall, we discovered a lot of new things about Mitosis.
LPO- Low power objective
HPO- High power objective
What if your cells don't reproduce or increase in number? What will eventually happen if your arm was wounded by a knife? If cells don't reproduce, how will your arm heal? All living organisms contain cells and in order for them to grow, survive, and eventually reproduce, the cells in their body should be able to multiply. The repair of the damaged parts of different organisms also requires the cells to increase in number in order to replace the damaged ones. The growth of the cells of many organisms generally has 3 main phases; cell division, cell enlargement, and cell differentiation. The types of cell division are usually Meiosis and Mitosis, in which the latter maintains the chromosome number of parent cells to daughter cells. Mitosis is generally divided into five stages; Interphase, Prophase, Metaphase, Anaphase, and the Telophase. The Interphase may also be referred to as the "resting stage" mainly because there seems to be no apparent changes occurring within the cell. The next stage is the Prophase wherein there is a gradual appearance of chromosomes and spindle fibers and also the disappearance of the nuclear membrane and the nucleoli. The Metaphase is the stage where there is a horizontal alignment of the chromosomes at the equitorial plate. The Anaphase is characterized by the division of the Centromere and the separation of the sister chromatids. The centromeres are pulled by spindle fibers toward the opposite poles of the cell. The Telophase is the stage wherein there is gradual disappearance of the chromosomes and spindle fibers, and the appearance of the nuclear membrane of each daughter cell. It is also during this stage where there is division of cytoplasm, usually a cell plate in plants and cleavage in animals.
All of the stages described above are intertwined with each other in a sense that Mitosis is a continuous process where the stages merge with another stage without any definite demarcation. All of these stages are important for an organism to be able to distribute...