C. Mulqueen Period 9

1. Human Cloning By Christopher Mulqueen

4. Genetic Disorder Single gene disorders are genetic conditions caused by the alteration or mutation of a specific gene in the affected person’s DNA. Single gene disorders are heritable and often run in families. Chromosome abnormalities usually happen as a result of an error in cell division. Meiosis is the name used to describe the cell division that the egg and sperm go through when they are developing. Normally, meiosis causes a halving of chromosome material, so that each parent gives 23 chromosomes to a pregnancy: Multifactorial traits result from the interaction of one or more environmental factors and two or more genes. In contrast to single gene disorders, multifactorial genes can express continuous variation, that is distribution of phenotypic expression from one extreme to another in a continuous fashion.