Down Syndrome

             One of the most common genetic defects is Down Syndrome. The story began is 1866, when a physician named John Langdon Down first described a set of children with common features who were distinct from other children, and had mental retardation. Although other people had previously recognized the characteristics of this syndrome, it was Down who first described the condition. At the beginning of his research, he referred to children diagnosed with Down Syndrome as "Mongoloids." Down based this name on his assumption that these children looked like people from Mongolia. This ethnic insult became an issue in the 1960s from Asian genetic researchers, and the term was dropped from scientific use. Instead, the condition became called "Down('s) syndrome."
             Down Syndrome originates with a fault in the chromosomes. Chromosomes are thread-like structures composed of DNA and other proteins, on which genes are located. Genes, which are units of information, are encoded in the DNA. Human cells normally have 46 chromosomes which are arranged in 23 pairs; one from each parent. Of these 23 pairs, 22 are alike in males and females. The 23rd pair differ because they are the sex chromosomes (X and Y). Each member of a pair of chromosomes carries the same information. However, variations of that gene may be present. For example, the genetic information for hair color is a gene, and the variations of that gene can be blonde, brown, red, etc.
             Every human cells divide in two ways. The first is ordinary cell division, mitosis, by which cells are duplicated to help the body grow. In this method, one cell becomes two cells which have exactly the same number and type of chromosomes as the mother cell. The second method of cell division (meiosis) occurs in the sex cells and consists of the nucleus of a cell splitting into four nuclei, each with a chromosome number that has been reduced by half. So, normal egg and sperm cells only have 23 chromosomes instead...

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Down Syndrome. (1969, December 31). In MegaEssays.com. Retrieved 18:54, March 28, 2024, from https://www.megaessays.com/viewpaper/90548.html