Csilla Szepe

Amazing Essays
Examining the inheritance patterns of genes of Drosophila melanogaster controlling some traits of eye color, body color, and wing shape by analyzing dihybrid crosses
Csilla Szepe Introduction
Our report will describe the experiment of three dihybrid crosses where we would like to understand if certain traits of Drosophila melanogaster follow the pattern of autosomal, unlinked inheritance.
The subject of our experiment is the fruit fly because it has a short, two week long life-cycle that allows rapid experimentation. It is also a well studied species, but more importantly the similarity of its genes to humans makes it a perfect model for understanding the pathogenesis of gene connected diseases. (reference) For example studies with the
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For cross two, our expectation was the ratio 9:3:3:1 of phenotypes red eyes / caramel body, red eyes / yellow body, white eyes / caramel body, and white eyes / yellow body respectively based on the autosomal, independently assorting inheritance pattern. For cross three, our expectation was the ratio 9:3:3:1 of phenotypes red eyes / normal wings, red eyes / vestigial wings, sepia eyes / normal wings, and sepia eyes / normal wings respectively based on the autosomal, independently assorting inheritance pattern. To test our hypotheses, we used the Chi-square test. First, we computed the expected values for every phenotype by multiplying the N/C value by the expected ratio, where N was the total number of offsprings regarding the given cross and C was the sum of the expected ratios (16 in all cases). Then, we computed the Chi-square values for every test by summarizing the (O-E)2/E values for every phenotypes, where O was the observed number of offsprings, and E was the expected number of offsprings. (reference) Finally, we compared the Chi-square value to our critical value 7.815 which we got from the Chi-square table as our experiments had a degree of freedom 3, and our level of significance was …show more content…
This means that we were not able to disprove that the genes controlling the sepia eye and vestigial wings are inheriting in an autosomal, independently assorting manner. References
Gonzalez, Cayetano. "Drosophila melanogaster: a model and a tool to investigate malignancy and identify new therapeutics." Nature Reviews Cancer 13.3 (2013): 172-183.
Morris, Ashley B., Cahoon, A. Bruce. BIOL 3251 Genetics Lab Manual Spring 2016, Middle Tennessee State University, Department of Biology. 2016
Nikhil, K. L., et al. "Role of temperature in mediating morning and evening emergence chronotypes in fruit flies Drosophila melanogaster." Journal of biological rhythms (2014): 0748730414553797.
Prüßing, Katja, Aaron Voigt, and Jörg B. Schulz. "Drosophila melanogaster as a model organism for Alzheimer’s disease." Molecular neurodegeneration 8.1 (2013):

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