10.1.2 Genetic properties of population

10.1.2 Genetic properties of population

Gene frequency

A character in an individual that passes on from generation to generation due to breeding of the parents is controlled by genes; it may be a single, pair or many pair of genes. The distribution of genes in different individual of the population is one of the properties of a population and is expressed as ‘Gene frequency’.

  • Assuming that a character is controlled by one pair of genes, A1 and A2,the frequency of A1 gene is the ratio of the number of A1 genes in the population to the total number of genes in the locus. The same procedure is true for gene-frequency calculation of A2 gene.
  • Hence the sum of the gene frequencies of the two alleles is equal to one, i.e. fA1+A2=1.

Genotypes are formed owing to pairing of genes (alleles) during union of gametes for zygote formation. If there are two alleles in a locus, A1 and A2, the number of a particular genotypes in relation to all the genotypes of the locus in the population is the frequency of that genotypes.

  • For example, the genotypes frequency of A1A1 genotypes is the ratio of the number of A1A1 individuals to the total number of individual in the population.
  • Therefore, the frequencies of a locus add to unity, i.e.

fA1A1+fA2A2=1.

Genotypes frequency is another property of the population. The gene frequencies can be calculated from genotype frequencies.

For example

fA1= fA1A1+1/2fA1A2.

Last modified: Thursday, 24 November 2011, 9:33 AM