Parthenogenesis Essay Example | Topics and Well Written Essays - 2750 words

Parthenogenesis - Essay Example What is parthenogenesis Why is it a form of asexual, rather than a sexual type of reproduction What are the organisms that have the ability to undergo parthenogenesis How can the knowledge of this type of reproduction benefit genetics, biology and science as a whole These are just some of the questions we will try to answer in this paper dedicated to delve deeper into the process of parthenogenesis. The most commonly known type of reproduction is the sexual reproduction. Two parents, one male and one female, are needed to produce an offspring. The Oxford Dictionary of Biology (2004) expounds that sexual reproduction is "a form of reproduction that involves the fusion of two reproductive cells (gametes) in the process of fertilization". In general, the gametes consist of a sperm from one individual and an egg from another. In a process called fertilization, the gametes unite to form a cell called the zygote, which develops into the offspring. The new individual is genetically different from its parents. Gametes are produced through a type of cell division called meiosis. In a cell produced by this kind of division, there are only half as many chromosomes as were in the cell that produced it. Sexual reproduction occurs normally, especially in animals. ... Gametes are formed by meiosis, a special kind of cell division in the parent reproductive organs that both reassorts the genetic material and halves the chromosome number. Meiosis thus ensures genetic variability in the gametes and therefore in the offspring resulting from their subsequent fusion. Sexual reproduction, unlike asexual reproduction, therefore generates variability within a species. However, it depends on there being reliable means of bringing together male and female gametes, and many elaborate mechanisms have evolved to ensure this (Oxford Dictionary of Biology, 2004). On the other hand, asexual reproduction is "a form of organic reproduction in which the parent organism does not exchange genetic material with another organism of the same species" (Ashworth and Little, 2001). In fact, there are four general types of asexual reproduction: 1.) Binary fission - Commonly occurring in protists and other unicellular organisms, binary fission closely resembles the process of mitosis, by which the cells of multicellular animals divide. The organism's chromosomes replicate (duplicate themselves) within the cell nucleus; the nucleus elongates with a group of identical chromosomes in each end; and finally the cell splits down the middle, along the short axis of the elongated nucleus, forming two "daughter cells", which are exact copies of the parent cell. 2.) Fragmentation - This occurs when an organism's body or body part breaks into two or more pieces; each part then develops into a completely new organism. The regrowth of tissue is referred to as regeneration. 3.) Budding - This process produces a small copy of the parent that begins as a growth on the parent's side and then breaks