Mitosis evolved in complex plants and animals for growth and repair. Mitosis, the division of a cell resulting in two identical daughter cells, prolongs an organism s life by replacing old, dead, and damaged cells. In complex animals and plants, mitosis occurs everywhere, except sex cells. Meiosis evolved in complex plants and animals to increase variation in offspring and to maintain the number of chromosomes from generation to generation.
Meiosis occurs in the sex cells of organisms, specifically the ovaries and testes in animals, and in the pollen and ovules of plants. In an organism where n = 8, the process of mitosis would be the following: In interphase, the DNA would replicate, resulting in 16 chromosomes. In prophase, two centrioles would move to the poles, the spindle starts to form, the nucleolus and nuclear membrane disappear, and the kinetochore fibers attach to the chinetochores. During metaphase, the chromosomes line up at the equator. In anaphase, the centromere splits, and the chromosomes move to the opposite poles (8 to each pole), pulled by the kinetochore fibers on the spindle. Lastly, during telophase, the spindle disappears, the nucleolus and nuclear membrane reappear, and the cell separates resulting in two new cells, exactly like the parent cell, each with 8 chromosomes.
Meiosis in an organism where n = 8 would be the following: During interphase I, the 16 chromosomes (2 n = 16) replicate to 32 chromosomes. In prophase I, centrioles would move to the poles, the spindle starts to form, the nucleolus and nuclear membrane disappear, and the kinetochore fibers attach to the chinetochores. Most importantly, the pairing of homologous chromosomes and crossing over takes place. This step is very important in creating variation among offspring. Next, the homologous pairs line up at the equator in metaphase I. In anaphase I, the homologues, each consisting of two sister chromatids separate, however the sister chromatids do not separate.
The Essay on Mitosis Lab Write-Up
Purpose:The purpose of this lab is to understand the phases of mitosis through a hands on experience and not just textbook information. The objective is to visually determine each phase through a microscope with a clear understanding of what is happening. With this knowledge and this visual a picture is to be drawn as descriptive as possible for each phase. Materials:The materials needed are; 1) ...
During telophase I, the spindle disappears, the nucleolus and nuclear membrane reappear, and the cell separates resulting in two new cells, with different parts of each parent cell, each with 16 chromosomes. Within interphase II, cytokinesis occurs, and the cell is split in two. Meiosis II closely resembles mitosis, except that the DNA does not replicate at interphase. During prophase II, the nucleolus and nuclear membrane disappear, and spindle fibers begin to appear. During metaphase, the chromosomes line up at the equator. At anaphase II, the sister chromatids separate from each other.
And in telophase II, the spindle disappears, the nucleolus and nuclear membrane reappear, and the cells separate resulting in four new cells, each with 8 chromosomes. The major differences between mitosis and meiosis is that mitosis results in two daughter cells exactly like the parent, whereas meiosis is sexual reproduction, resulting in 4 daughter cells that have a combination traits from both parents.
