Two Types of Cell Division - Lab Report Example

Mitosis The living things are made of cells. There are two types of cells they are unicellular and mutlicellular. The multicellular cellsdivide somatically by mitosis. In this process, the each cell divides into two daughter cells. These cells divide by a process called mitosis. Mitosis is also called as nuclear splitting which is accompanied by cytokines is (i.e., the cytoplasm divides into two). These two steps constitute the cell cycle. All the cells grow divide and multiply among themselves. (Cregan 2007). In our experiment, the mitotic stages of onion root tip and white fish blastula were identified. The prepared and preserved slides were observed under the microscope. The different stages of the mitosis such as interphase, prophase, meta phase, anaphase and telophase of the cell along with the cytokinesis were identified and the stages were differentiated. Introduction: All the living things are made of cells. In a multi-cellular organism, two types of cell division occur: they are mitosis and meiosis. Mitosis or Somatic cell division is the process in which one cell divides into two equal cells with genetic identity. The cell division is necessary for the growth and development of the cells. The transformation of information from one generation to another is called heredity and the genes which are the fundamental part of the chromosome are responsible for the transformation. The chromosomes are present in pairs. Each pair is responsible for a specific part or function in the cell. These chromosomes are distributed equally in new cells during mitosis. Mitosis is thus described as the chromosomal division. This chromosomal division is accompanied by the cytoplasmic division called as cytokinesis. The mitosis along with cytokinesis results in the formation of two daughter cells. This is also called as cell cycle. Cell cycle is the period in which the cell divides and becomes two daughter cells. The cells cannot split into two halves, so they create the copy material and divide. The length of the cell cycle varies based on the type of cell. The interphase is the long period in the cell division, where the cell prepares itself for the cell division and performs the normal activities. It is in the mitotic phase the cell divides. There are four stages in mitosis. They are prophase, metaphase, anaphase and telophase. (Allen and Harper 2011). Prophase is the first stage of mitosis which is visible. The chromosomes, which are randomly distributed in the cytoplasm condense to form the distinct part. They are held in a single line. Metaphase is the stage in which the chromosome is attached to the centromere through the spindle fibril. The centromeres are connected to the centrioles and the centrioles pulls the chromatids to the opposite directions. This step initiates the cell division. Anaphase is the stage where the chromosomes move to the position of centriole. The chromosomes are seen as complete sets in the opposite side of the cell. Telophase is the last stage of mitosis in which the chromosomes begins to loosen itself from the thicker rigid structure into thin filaments. The division of the cytoplasm starts at this particular point. Materials required: Prepared slide of Allium root tip Prepared slide of white fish blastula. Microscope. Method: 1. The prepared slide of allium (onion) root tip was mounted on the microscope. 2. The 4x objective lenswas used to focus the centre of the slide. 3. The cells undergoing the four stages of mitosis such as prophase, metaphase , anaphase and telophase were identified in the slide using the 10x magnification. 4. Using the 40x magnification in the microscope, the distinct chromosomes and the other cell structures were identified. 5. Similarly, the whitefish blastula slide was mounted on the microscope and the blastula sections were observed using the 4x magnification. 6. Then 40 x magnification was chosen to examine the chromosomes. The cells in each phase of mitosis were identified. Result: For the Onion Root tip: 1. In the interphase stage, nucleus, nucleolus, cell wall and chromatin were identified. 2. During the prophase stage, the chromatids (which look as a dyad) and spindle fibers were identified. 3. At the metaphase stage, the chromosomes were found as distinct structures. 4. At the anaphase stage, groups of chromosomes were identified. 5. At the early and late telophase stages, the cell plate and chromosomes were identified. For whitefish blastula stage: 6. The interphase stage in the cell was located and the nucleus, nucleolus, centrioles and cell membrane were identified and drawn. 7. In the prophase stage, the chromosomes, spindle fibres and asters were identified. 8. At the metaphase stage, the chromosomes present as dyads and asters were identified. 9. During the anaphase stage, distinct structures of chromosomes were identified. 10. Finally at the telophase stage, cell and other parts of the cell were identified. Conclusion: Mitotic cell division involves two steps namely karyokinase and cytokinesis (division of nucleus) includes 4 phases namely prophase, metaphase, anaphase and telophase. Prophase: It is the first phase in karyokinesis. It takes the largest duration and is characterized by the following changes. 1. Condensation of the chromosome due to coiling. 2. Duplication of the chromosome becomes distinct as long thin threads. 3. The nucleolus and the nuclear membrane disappear in the cytoplasm. 4. The spindle fiber disappears in the cytoplasm. Metaphase: This phase has shorter duration and brings in many changes in the cell: (i) Chromosome become sharply thickened and arranged them along the equator, forming the equatorial plate. (ii) Centro mere lie along the equator are the arms towards the poles and then a contract with the spindle fiber at the equator. (iii) Centro mere divided at the end of the metaphase. Anaphase: It is the shortest of all mitotic stages and it is characterized by the following changes. (I)Separation of the sister chromatin and their movements are the opposite poles of the cell. The Centro mere is the point of movement and hence moves first along the axis taking the sister chromatic to opposite poise. (ii) The daughter chromosomes are highly condensed and from a daughter packed group at each poles of the spindle. This marks the end of anaphase. Telophase: It is characterized by the following events. (i)The daughter chromosomes are at the opposite poise and they are uncoiled to bear slender thread again. (ii)The nucleolus and the nuclear membrane begin to reappear. (iii)Cytokines occurs. (iv)It is the division of cytoplasm between the nucleuses. The cytoplasm constrict at the middle. The constriction depends till the cell divisions into 2 daughter cells. In the plant cells, the cytokinesis results in the production of two identical daughter cells of same size and they gradually divide along the cell plate and creates a new cell wall. In the animal cells, cytokinesis results in the formation of a cleavage furrow results in the production of two daughter cells. Here the constriction of the cell membrane starts from the outside to the inside. The animal cells develop well defined microtubule network, which plays an important part in the cytokinesis. (Nagata, Inzae and Matsuoka 2006). This process was also called as “pinching in”. (Cregan 2007). Figure 1: stages of mitosis. (Bijlani and Manjunatha 2010). Mitotic divisions are necessary in cell systems because, it divides the genetic material into two equal halves and provides the same information to all the cells of the same type. The cells divide and enable the organism to be alive. Though the need for mitosis varies with each and every organ, without mitosis, there is no growth of the organism and no repair of the worn out cells. The main essence of cell division lies in the replication and division of the nuclear materials. (Bijlani and Manjunatha 2010). References: Allen, C and Harper, V., 2011. Laboratory manual for Anatomy and Physiology, John Wiley and Sons. Bijlani, RL and Manjunatha, S., 2010. Understanding Medical Physiology: A text book for Medical Students, JP medical ltd. Cregan, ER., 2007. All About Mitosis and Meiosis: life science, Teacher created materials. Nagata, T., Inzae, D and Matsuoka, K., 2006. Tobacco by – 2 cells: from cellular dynamics to omics , Springer. Read More