Fruit Flies as a mean of genetic study.
In Mendelian genetics, one can study how heritable traits are passed from parents to their offspring. It gives us a way to predict the phenotypic and genotypic ratio of offspring. There are two kinds of alleles noticeable in genes: dominant and recessive alleles. A dominant allele will always be expressed in a phenotype. It doesn’t matter whether it is Homozygous or Heterozygous. Recessive alleles on the other hand do not have this same quality. A recessive allele will only be expressed if the genotype is homozygous. Heterozygous genotypes containing one dominant trait and one recessive trait will only express the dominant trait in the phenotype. If we do a pure breeding (monohybrid cross) between two parents, where one parent contains dominant homozygous alleles for black eyes and another parent contains recessive homozygous alleles for brown eyes, we will find all black eyes among the offspring of F1 generation. We can demonstrate this by using a punnet square.
Bb | Bb |
Bb | Bb |
All (Bb) heterozygous genotypes are expressing the phenotype of black eyes. If we do another cross for F2 generation we will find 2 heterozygous black eyes, 1 homozygous black eye and 1 homozygous brown eye among the offspring. The punnet square is as follows:
BB | Bb |
Bb | bb |
The genotypic ratio is – 1(BB):2(Bb):1(bb). The phenotypic ratio is – 3:1.
DROSOPHILIA MELANOGASTER AS A MODEL FOR STUDYING GENETICS
Drosophila melanogaster also known as the fruit fly is used commonly in the study of genetics. Scientists prefer this particular breed of flies because they are easy to take care of, they breed quickly,...