Welcome              Orchids            Wetlands              Orchid Genetics               Our Plan             About Us

Enzyme electrophoresis can be performed to determine the genetic variation of organisms.  A population of organisms of the same species, may have only one form of a given enzyme.  If, however, there are two enzymes that differ in charge they can be distinguished by electorophoresis. These enzyme variants are a result in small changes in the DNA sequence of protein coding genes, altering what amino acids are incorporated into the proteins. When a slurry of a tissue is placed in a starch gel and subjected to an electrical current, the enzyme molecules with different electrical charges with migrate through the gel at different rates.  This procedure is known as electrophoresis.  After electrophoresis the gel is bathed in cofactors for a particular enzyme and dye that precipitates when the cofactor and enzyme react. This allows the observation of the mobility of each enzyme based on the position in the gel. This data is then used to determine allele frequency in populations of species.

These two forms of the same enzyme are called isozymes.  The two isozymes may be different because they are two different enzymes, each coded for by its own genetic locus.  This occurs if the genome had two copies of genes for functionally identical enzymes.  Alternatively, the isozymes could correspond to charge variations of the gene products from a single genetic locus, i.e., two alleles of the same gene, in which case the charge isomers are called allozymes.

Allozyme data are used to track and to characterize genetic variation in natural populations.  An individual can be either homozygous or heterozygous at a given allozyme locus.  If all of the individuals in a population are homozygous for the same charge isomer, then the population is said to be monotypic,  lacking in genetic variation for that enzyme.  If some of the individuals in a population are homozygous for one allozyme and others are homozygous for the other allozyme, this indicates genetic variation within the population for that enzyme.  Populations that are highly inbred or have recently been through a population bottleneck usually display a low degree of allozyme variation.

If there is allozyme variation in the population, then one can calculate (using the Hardy-Weinberg law) the expected frequencies of heterozygotes.  These values can be used in aiding conversation efforts.    Knowing the allele frequency allows researchers to to determine genetic differentiation among populations.