Mitosis and Meiosis Essay -- essays research papers

Cell division may happen by either mitosis or meiosis, depending on what type of cell is invovled. Mitosis is a process by which a cell divides to form two daughter cells. They each direct the same exact number and kind of chromosomes as the parent cell. pupillary reflex occurs in the primary sex cells leading to the formation of viable nut case and sperm cells. They reduce the number of chromosomes to half in each gamete so that when they are getting furtilized, the species chromosome number is kept even. Mitosis happens in the reproduction of unicellular organisms and in the addition of cells to a tissue or organ in a multicellular organism.There are four pointednesss of mitosis. The first set up is the prophase. In this order the chromosomes become shorter and thicker and they each consist of two chromatids. The nuclear membrane begins to disintegrate. The centrioles in animal cells, fungi, algae and some other ferns threefold and a pair bleed toward each pole and the ch romosomes begin to pretend toward the equator of the cell.The second stage is called the metaphase. In this stage the centrioles move to the poles. The chromosomes line up at the equator of the spindle and the spindle fibers are attached to the centromeres connecting them to the poles of the spindle.The third stage is called the anaphase. By this time, the centromeres split apart. The chromatid pairs of each chromosome separate from each other and they move quickly in opposite directions, one toward each pole.The last stage is cal...