Test cross

[4] Rediscovery of Mendel’s work in the early 1900s led to an explosion of experiments employing the principles of test crosses.

From 1908-1911, Thomas Hunt Morgan conducted test crosses while determining the inheritance pattern of a white eye-colour mutation in Drosophila.

[6] Monohybrid, also called “single gene test cross”, is used to observe how homozygous offspring express heterozygous genotypes inherited from their parents.

[citation needed] In conducting a monohybrid cross, Mendel initiated the experiment with a pair of pea plants exhibiting contrasting traits, one being tall and the other dwarf.

[citation needed] Mendel furthermore determined to explore the outcome of crossing two plants that were hybrids for a single trait.

[9] To perform a test cross with D. melanogaster, select a trait with a known dominant and recessive phenotype.

It can be a time-consuming process as some organisms require a long growing time in each generation to show the necessary phenotype.

Test crosses are also not applicable with codominant genes, where both phenotypes of a heterozygote trait will be expressed.

In addition, the environment affects the expression of numerous genes, therefore making the test cross inapplicable in many cases.

Genetic testing and genome mapping are modern advances which allow for more efficient and detailed information about one’s genotype to be determined.