Conventional Cytogenetic: A Report

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This report is studying about conventional cytogenetic, and we will focus on a technique called ‘karyotyping’. This repot is going to introduce about the definition, the history and the improvements of karyotyping made before, what is the process and the working principle of this technique and also how if can be applied in our daily life. Karyotyping is a test to examine chromosomes in a sample of cells, which can help identify genetic problems as the cause of a disorder or disease. The term ‘karyotyping’ is come from ‘karyotype’, which is the characteristic chromosome complement of a eukaryote species. The preparation and study of karyotypes is part of cytogenetics. In the middle and late 18th century, scientists were aware of the presence of chromosomes but had difficulty studying them because of their extremely small size. Chromosomes were first observed in plant cells by a scientist called Karl Wilhelm von Nägeli in 1842, but since the samples they took had small chromosomes. After the development of genetics in the early 20th century, when it was appreciated that the set of chromosomes, the karyotype was the carrier of the genes. Another scientist Levitsky seems to have been the first to define the karyotype as the phenotypic appearance of the somatic chromosomes, in contrast to their genic contents. It took until the middle 1950s until it became generally accepted that the karyotype of humans included only 46 chromosomes. Rather interestingly, the great apes have 48 chromosomes. Human chromosome 2 was formed by a merger of ancestral chromosomes, which reducing the number. Investigation into the human karyotype took many years to settle by two famous scientists: Hans von Winiwarter and Theophilus Shickel Painter. Hans von Winiwarter examined normal human diploid cells to try and define the number of chromosomes that humans have. In his time, guesses ranged from 16 to 36. He used the most powerful microscopes available in his day in one of the first accurate...
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