Drosophila Melanogaster - Sex Linkage and Inheritance of Genes Through Cross Breeding

1281 words 6 pages
Drosophila melanogaster - Sex linkage and inheritance of genes through cross breeding

This experiment looks at the relationship between genes, generations of a population and if genes are carried from one generation to another. By studying Drosophila melanogaster, starting with a parent group we crossed a variety of flies and observe the characteristics of the F1 generation. We then concluded that sex-linked genes and autosomal genes could indeed be traced through from the parent generation to the F1 generation.
Sex linkage and inherited genes allow us to predict and understand how and why certain animals and plants inherit features from their parents while some don’t. Sex linkage is the condition in which a
…show more content…

For our individual group results see appendix. White Eye (W) Female x Vestigial (Vg) Male | White Eye (W) Male x Vestigial (Vg) Female | Wild type female | 51 | Wild type female | 36 | White eye male | 76 | Wild type male | 24 |

The table shows that in the (W) Female x (Vg) Male, out of the 127 F1 flies scored, 51 were wild type female and 76 were white eye male.

Note that in the F1 generation, only wild type and white eye males were present, and none with vestigial wings. This is because the (Vg) trait is recessive and will not show until the F2 generation.

The two traits studied in this experiment were vestigial/ normal wings and white/ red eyes. The vestigial (Vg) trait is controlled by an autosomal gene and not sex-linked (Helmbold, J. 2006). This means that in the (W) female x (Vg) male the genotypes would be, Female (Vg+ Vg+ - wild type) and male (vg vg – as vestigial wings are recessive). The punnet square for the F1 is as follows for vestigial wings: | Vg+ | Vg+ | vg | Vg+vg | Vg+vg | vg | Vg+vg | Vg+vg |

The punnet square shows that all the offspring in the F1 generation carry the genotype Vg+vg making them heterozygous. This means that none of the offspring have the vestigial wing phenotype but do carry it in their genes, which surfaces in the F2 generation.
The white eye trait on the other hand, is sex linked. Therefore in the (W) male x (Vg) female experiment the resulting F1 generation