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What Are Allele Frequencies?

Human genetics is a complex subject. DNA decides every aspect of a person's features, from hair color to blood type. Allele frequency is just one of the many branches of genetic research. Its purpose is to examine how certain populations carry specific traits. Understanding genetics provides an excellent insight into how nature designs itself.

  1. Chromosomes

    • Chromosomes are the containers of human DNA. There are 46 chromosomes in human cells, split into 23 pairs. These pairs of chromosomes are called alleles. When scientists study allele frequency, they look within the chromosomes to isolate certain alleles and count how often they occur in a given population.

    Alleles

    • Alleles are the components of human genes that determine appearance. They are referred to as coding alleles. However, some alleles seemingly have no role, so they are labeled junk DNA. Allele pairs can be either homozygous or heterozygous. Homozygous alleles carry identical blueprints. For example, if each parent passes down the gene for blue eyes, then the pair will be homozygous, or identical. However, if the allele is split between two traits, it is heterozygous, meaning one may carry genes for blue eyes, while another could contain genes for brown eyes. In this case, appearance is determined by the dominant allele. For eye color, brown is dominant, therefore the child will have brown eyes.

    Allele Frequency

    • Allele frequency is the study of how diverse the gene pool is within a population. In other words, it determines how common a certain trait is. Once the complicated task of locating the alleles is finished, determining the frequency is quite simple. For example, scientists will look at the chromosomes from Population "A" and notice that 20 percent of them contain the alleles for blue eyes. This means that one in five chromosomes within that population will have the blue allele.

    Microevoloution

    • Allele frequencies are a major force behind microevolution. Microevolution involves minor alterations over time that eventually change certain characteristics of different animals. As alleles are passed from one generation to the next, their frequency changes. Since alleles determine the physical aspects of an organism, the gradual increase or decrease of allele frequencies will eventually alter the nature of a species.

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