Allozymes

Allozymes are the allellic differences of enzymes encoded within structural genes. Allozymes were the first established molecular markers used by researchers. The principle behind allozymes is that protein differences in enzymes can be detected by native gel eletrophoresis by substituting amino acids and looking at the change in size and charges.

One of the advantage of using allozymes as genetic markers is the relative simplicity of the procedure. There is no need to extract DNA using probes or depend on the availability of sequence information. Due to their simplicity they are also very cost effective. This makes them the preferred way to check genetic differences within large population. They are also commonly used to look at the allelic differences between closely related species.

One of the disadvantages of this test is the relative few number of informative molecular markers (polymorphism). This makes this method unappropriated for genetic mapping and association studies.

Refences
^ VanTrueren, R. (2015). Allozymes. Retrieved from https://www.wageningenur.nl/en/show/Allozymes.htm

^ Schlötterer, C. (2004). Opinion: The evolution of molecular markers — just a matter of fashion? Nature Reviews Genetics, 5(1), 63–69. http://doi.org/10.1038/nrg1249