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Ward's World+McGraw Hill Mendelian Genetics Activity

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Mendelism Original Article by: Michael R. Cummings, Department of Biological Sciences, University of Illinois, Chicago, Illinois. + ward ' s science Key Concepts • Gregor Johann Mendel, an Augustinian monk, formulated the fundamental principles governing the transmission of genetic traits. The term Mendelism describes these basic laws of ge- netic inheritance. • Mendel's work, which has been confirmed by genetic crosses and breeding applications with many different organisms, is regarded as the beginning of genetics as an organized scien- tific discipline. • Mendel proposed that each plant (the organism that he studied) contains a pair of factors (genes) for each trait. The trait that is expressed in the first filial generation (F1) is controlled by a dominant factor, whereas the unexpressed trait is controlled by a recessive factor. • The most simple Mendelian cross, called a monohybrid cross, involves only one pair of traits. A cross that involves two pairs of contrasting traits is known as a dihybrid cross. • Mendel postulated that factors (genes) separate or segregate from each other during gamete (sex cell) formation. • The traits of offspring are determined by segregation, independent assortment, and random fertilization. Access to this article is being offered to Ward's World readers for free from McGraw Hill's AccessScience. An award-winning online gateway to scientific knowledge, AccessScience offers exclusive articles writing by prominent scientists, links to primary research material, videos and animations, plus faculty-designed curriculum maps for teachers. Fig. 1: Schematic representation of a monohybrid cross. Pure-bred yellow and green pea strains are crossed and yield a typical 3:1 ratio (3 yellow and 1 green) in the F2 generation. Y and y represent the yellow and green factors (genes), respectively. P represents the parent generation, F1 represents the first filial generation, and F2 represents the second filial generation. (Copyright © McGraw Hill's) Fundamental principles governing the transmission of genetic traits, as discovered by Gregor Mendel. Mendelism is the term used to describe the basic laws of genetic inheritance (Fig. 1). These operating laws were formulated by Gregor Johann Mendel (1822–1884), an Augustinian monk, who conducted a number of notable experiments on plant hybrids. Mendel published his scientific work in 1866; however, it went largely unheralded until 1900, when other investigators performed similar hybridization experiments and brought his work to the attention of the scientific world. The rediscovery of his work is regarded as the beginning of genetics as an organized discipline. Since then, genetic crosses and breeding endeavors with many different organisms have confirmed the fundamental nature and significance of Mendel's work.

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