Question

When does a geneticist need to carry out a test cross how is it carried out?

Answer 1

hey,
In genetics, a test cross, first introduced byGregor Mendel, involves the breeding of an individual with a phenotypically recessiveindividual, in order to determine the zygosityof the former by analyzing proportions of offspring phenotypes. Zygosity can either beheterozygous or homozygous. Those that are heterozygous have one dominant and one recessive allele. Individuals that are homozygous dominant have two dominant alleles, and those that are homozygous recessive have two recessive alleles.[1]

The genotype that an offspring has for each of its genes is determined by the alleles inherited from its parents. The combination of alleles is a result of the maternal and paternal chromosomes contributed from each gameteat fertilization of that offspring. Duringmeiosis in gametes, homologous chromosomes experience genetic recombination and segregate randomly intohaploid daughter cells, each with a unique combination of maternally and paternally coded genes.[2] Dominant alleles will override the expression of recessive alleles.

Test crosses are used to test an individual's genotype by crossing it with an individual of a known genotype. Individuals that show the recessive phenotype are known to have a homozygous recessive genotype. Individuals that show the dominant phenotype, however, may either be homozygous dominant or heterozygous. The phenotypically dominant organism is the individual in question in a test cross. The purpose of a test cross is to determine if this individual is homozygous dominant or heterozygous.
Hope it helps u friend...