BIOL 1090 Chapter Notes - Chapter p.52-56: Mendelian Inheritance, Roman Numerals, Genetic Counseling
17 Oct 2016
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Document Summary
Humans, unlike experimental organisms, do not produce many progeny, making it difficult to discern mendelian ratios, and humans are not maintained and observed in a controlled environment. For these and other reasons, human genetic analysis has been a difficult endeavor. Pedigrees are diagrams that show the relationships among the members of a family. A horizontal line connecting a circle and a square represents mating. The offspring of the mating are shown beneath the mates, starting with the first born at the left and proceeding through the birth order to the right. Individuals that have a genetic condition are indicated by colouring. The generations in a pedigree are usually denoted by roman numerals. Recessive traits are not as easy to identify because they may occur in individuals whose parents are not affected; sometimes several generations of pedigree data are needed to trace the transmission of a recessive allele.
