Heredity

Gregor Mendel found the patterns of simple inheritance in 1860 which are the basic principles scientists still use today. He identified the hereditary unit, genes. The principle of segregation states that during the formation of gametes, the two traits carried by each parent separate. This can be shown in the following figure: Mendel's principle of independent assortment states that during gamete formation, the alleles of a gene for one trait (Tt), segregate independently from the alleles …

…codominance is expressed among the alleles, the traits exhibit polygenic inheritance. For example, people are not simple short or tall, but they show a progression of heights. A chi-square test is used to verify the predicted ratio of a cross to institute the pattern of inheritance. It is determined by the difference between expected and observed results squared, d^2, divided by the expected results, e. In other words, chi square is determined by d^2/e.