DOC PREVIEW
SC BIOL 101 - Drosophila Melanogaster

This preview shows page 1-2-3-4 out of 12 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

BIO-101L EXPERIMENT 9: DROSOPHILA MELANOGASTERMENDELIAN GENETICS FOR AN UNKNOWN DIHYBRID CROSSUSING AN F2 GENERATION TO DETERMINE P1 GENERATIONReport Author: Cameron G. KahnReport Submitted: 12 November 2014Data Collected: 29 October 2014Laboratory Partners: Nilesh SyamTaylor HollingsworthTeaching Assistant: Amanda HavighorstAuthor’s Affiliation: Department of Chemistry and BiochemistryUniversity of South CarolinaColumbia, SC 29208I pledge that my work meets the standard of the USC Honor Code.ABSTRACTThis experiment was performed to study phenotypes of the Drosophila melanogaster which is simply a red-eyed fruit fly. By studying phenotypes of the fly, a better understanding of genetics can be accomplished. In the case of this experiment, the phenotypes being studied were the wild-type eyes (red), sepia-brown eyes, wild-type wings and the shriveled wings (both Vestigial and Apterous) in the F2 generation. Using the offspring observed from the F1 parent generation, the parental P1 generation flies mated at the supply company was determined to be homozygous dominant and homozygous recessive. The observed number of flies for each phenotype was compared with the expected number for each phenotype using Mendel’s Law to see if 1the results followed Mendelian Genetics. The null hypothesis was that the results from the class data collected for the observed number of flies for each phenotype would follow Mendelian Genetics. A chi-squared statistical test was performed and the results showed that the observed data did not follow the 9:3:3:1 ratio as described by Mendelian Genetics therefore the null hypothesis was rejected because the data observed was significantly different at the 95% confidence interval than what was expected using Mendel’s Law which concludes that the results from the experiment could have been due to random error.INTRODUCTIONThe drosophila melanogaster is a species of fly that is heavily studied in biology to understand the basics of genetics, development and cellular processes. The fly is a common vinegar fruit fly that is likely to be seen around bananas at the supermarket. The drosophila fly acts as a model species for understanding more complex species such as higher eukaryotes all the way up to humans through the study of its genome and its ability to culture quickly in lab [1]. In the early twentieth century, a scientist by thename of Thomas Hunt Morgan first observed white eye mutation in drosophila and began experimenting with crossing with wild-type drosophila. He later performed crossing the mutant drosophila and therefore concluded that the red eye offspring from the first cross with the white eye male and the wild-type female was dominant over the recessive white eyes [2]. After further study, Morgan realized that these phenotypical traits were sex linked and relied on the X chromosome due to his observation that all the females had red-eyes while the males had both red and white eyes. From here, crossing the drosophila flies to expose other desired phenotypes began. One of 2Morgan’s most important conclusions is that the number of red eye versus white eye drosophila follows Mendelian Genetics and the number of flies that display either phenotype can be predicted using Mendel’s ratio of 3:1 [2]. Gregor Mendel was an Augustinian monk who created the basic laws regulating the traits passed on from one generation to the next (parent to offspring). Mendel’s experimentation with pea plant’s seed color, pea color and the crossing of the peas between the years of 1856 to 1863 founded the understanding of heredity and from this came the formation of the laws of Mendelian inheritance [3]. Around 1866, Mendel discovered the “invisible” elements known today as genes. The laws of inheritance created by Mendel serves to describe how alleles are represented in gametes and offspring [2]. The background provided by Mendel’s research back in the 1800s is still the foundation for modern genetics today.The focus of this experiment was on the unknown dihybrid cross of the offspring from the parent generation. The experiment was performed with the understanding of Mendel’s first and second laws of inheritance. Mendel’s first law is called the “law of segregation” and can be defined as when the parental alleles segregate during gamete formation therefore creating gametes that only contain one allele for every gene [2]. Mendel’s second law is known as the “law of independent assortment” and it stated that allelic pairs separate self-reliantly of other pairs. From the second law, Mendel concluded through observation that there is a 9:3:3:1 ratio of all the possible combinations of phenotypes (traits). With the knowledge provided from the first and second laws of inheritance, the ratio of phenotypes and genotypes for offspring can be predicted [4]. Furthermore, one can work backwards based on the outcome of either a 3monohybrid cross or in this case, a dihybrid cross, to determine the genetic make-up of the parent generation. For this experiment, this was done using a Punnett square in order to map out the outcomes from the cross. In this experiment, the purpose was to apply Mendel’s laws in order to study inheritable traits of the drosophila melanogaster from an unknown dihybrid cross and then determine the parent generation. From the knowledge of Mendelian Genetics, the null hypothesis was that the four phenotypes displayed in the dihybrid cross would follow the 9:3:3:1 ratio predicted using Mendel’s second law of inheritance. METHODSThis lab was performed over two weeks’ time. The first portion of the lab was to set up two culture tubes, one for each cross; however, only the unknown dihybrid cross vial was significant in observing for this experiment. A spoon full of dry high carbohydrate media was obtained and placed into the first culture vial. The vial was then filled with about 10mL of water until the media was slightly moistened. The vial waslet standing for a brief minute or so and water was added until the surface displayed a shiny appearance. One to two yeast grains were then added to the vial so that not too much carbon dioxide builds up which slows development of any offspring. The vial was closed using cotton balls and then let sit for about 5 minutes to ensure the media solidified. If the media was not solidified after the 5 minutes by tipping the vial on its sideand checking for any media to pour down the side of the


View Full Document

SC BIOL 101 - Drosophila Melanogaster

Documents in this Course
Load more
Download Drosophila Melanogaster
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Drosophila Melanogaster and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Drosophila Melanogaster 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?