Jessica Olivares

11/22/2014

Bio 3103

Fly lab report

Fruit Fly Report

Hypothesis

In setting up the fruit fly experiment the predicted mutant phenotypes were to be compared in the observed F1 generation and F2 generation. In order to make the appropriate phenotypic ratios we based the F1 and F2 to generate two mutants that were used to set up the parental cross. In the observed F1 generation the white eye mutant was located on the male drosophila melanogaster. The following white eye mutation could be set up by the following white type white eye female and a combination of wild type male with vestigial wings. Since only the F1 generation was observed during the beginning of this experiment the cross between the F1 generations for the given cross was identified for the P generation.

In the following F2 generation a new mutant was observed in both male and females, 2 different phenotypes the white eye gene was again observed following a new mutant; vestigial wings. In predicting this outcome the suggested prediction for the following traits had to do with the outcome that was created by setting up wild type females with white eyed males.

Suggested outcomes of the following genes could be the possible aspect that the two genes assort independently and or dependently from each other. Both traits are located in different chromosomes which have different locations in their according chromosome. Such as the white eye gene is located on the X chromosome. On the other hand the white eyes mutation is also a sex linked gene which can have a larger possibility for males to exhibit the white eye gene trait due to where the gene is located on the chromosome.

For the given outcomes of the genes if predicted genes were autosomal than the reciprocal crosses would generate a same F1 phenotype because the genes are carried on genes that do not distinguish based on sex. On the other hand if the genes are different such as one is autosomal and the other gene is sex linked than the following genes would also create reciprocal crosses that generate different F1 phenotypes because the genes carry different genotypes and once crossed the number of phenotypes would be different according to the overall phenotypic ratios.

Methods

For lab one the Drosophila melanogaster species was introduced by indicating the 3 principles of Mendel. The purpose of the lab was to introduce us to the basic structure and the life cycle of fruit flies and the basic techniques of identifying fly mutants and wild type fruit flies.

Lab one consisted of several different exercises that helped us identify and understand the differences of fly mutants and wild type fruit flies. For exercise #1 we obtained a Carolina Drosophila melanogaster manual. The required tools that we used included culture vessels, plugs, medium; marking pencils or permanent pens, labels, fly nap, white sorting cards, fine sorting brushes and a microscope were all used for this experiment.

The instructor showed us how to make a fly food vial and we prepared fly vials. We first obtained disposable vials, we mixed an equal amount of fly food and distilled water. Then we mixed gently until a homogenously blue food solidified. Then if necessary we wiped away remaining liquid on the vial. After for exercise #2 we identified the life cycle of the fruit flies and answered questions after that we set up groups of 3 members and obtained a wild type Drosophila culture from front bench and observed under the microscope. After we also identified the stage and the sex of the fruit fly. Then we learned to anesthetize adult flies and we placed them under the microscope for further identification.

To anesthetize flies we obtained empty vial with foam stopper and added 2 drops of fly nap to the inside of the foam stopper. Then we placed the foam stopper in vial. We then transferred the flies in the empty vial, we removed the stopper/ vial and then gently tapped the bottom of the Drosophila culture. Then we quickly removed the stopper from the culture and placed the foam stopper on the napping chamber. Then watched and waited for about 60-90 seconds until fruit flies stopped moving and after that removed fruit flies from vials for examination. Under the microscope we distinguished and separated male and female flies.

In exercise #3 we identified different fly mutants and repeated the process of anesthetize to observe and compare from mutant to wild type fruit flies. For exercise #4 we reviewed Mendel’s law of genetics, punnet square, chi square, monohybrid cross and Mendel’s dihybrid cross.

For lab two the purpose of the lab was to observe the basic techniques of culturing flies and set up a crosses between different fruit flies and to provide proper nomenclature. In this lab we were given several exercises that consisted of table and information on how to help us understand the techniques we will be using for the purpose of this lab.

In exercise #1 we learned the Drosophila nomenclature, based on the phenotype and the gene was given a name. Then we used the genotype to track other genes at a time. For exercise #2 we predicted cross outcomes by using two examples given to us in the unit file. Then we were assigned two traits from the instructor and wrote down the crossing scheme and predicted the phenotypic ratios in the given examples, generations. For exercise #3 our group of 3-4 people obtained the fruit flies that were used to set up the F1 generation and for this exercise the F1 flies

were the offspring’s of an unknown P cross. At the end of this exercise the mission was to identify the 2 mutants that were used in the original cross and to understand how they were set up by breeding F1 flies and tracking the inheritance patterns. For this experiment we received a vial with name of a cross and all the required information.

For lab three we conducted scientific methods to solve genetic crosses, which included making a hypothesis, designing an experiment, carrying out the procedure and interpreting the results. After the fly breeding, data collection and analysis my group discussed and collaborated the importance of our data and proposed an explanation for alternative outcomes.

For this following lab we included the fly breeding techniques to help collect 1000 or more flies. For this part we used two methods which included transferring flies into new vials. Then examined flies for their phenotypes. For the first method if we did not need to examine flies for their phenotype then we put them into a new vial so it can be separated from the new vials to the new F2 generation. At the beginning of the lab we made several examinations of the fruit flies and for 23 days our group monitored the flies during the appropriate days or at the end of the Drosophila Melanogaster life cycle. During these 23 days we followed the breeding patterns and collected the amount of fruit flies examined per day. Carefully each day we gathered our data collected and at the end of lab we did a summary of the collected analysis.

Results

About 10 days of data collection Data collected 11/11/2014-11/20/2014 Observed F1 and F2 generation fruit flies

F1 Generation 11/11/2014Male Female

Wild Type 24 31White Eyes 4 N/AVestigial Wings N/A N/AWhite Eye; Vestigial wings N/A N/ATotal Counted 28 31

The table above shows the constructed F1 generation with one mutant being recognized in 4 male fruit flies. The following mutant recognized was the white eye mutation. 28 counted males with 4 being white eyes in the F1 generation. 31 counted females were counted in the F1 generation with all being classified as wild type.

F2 generation

Date Counted

Vial #

wild male

wild femal

e

white eyed male

white eyed

female vestigial male

vestigial female

vestigial white male

vestigial white female Total

11/11/2014 SR 7 11 2 2011/12/2014 1 3 3 2 8

JO 5 4 1 1 1 12

11/13/2014 1 3 20 5 4 324:00pm 4 0

11/13/2014 SR 3 6 911/18/2014 1 8 21 5 2 4 40

11:15am 4 16 25 9 2 3 4 5911/18/2014 1 0

7:30pm 4 3 6 911/18/2014 JO 52 24 6 5 6 1 94

11/18/2014SAR

1 27 65 27 3 17 1 140

11/18/2014SAR

2 15 60 15 9011/18/2014 SR 19 42 7 2 4 7411/19/2014 1 9 4 9 3 25

2:15pm 4 7 6 4 1711/19/2014 JO 10 15 4 3 32

SAR 10 11 5 2 4 1 33SR2 16 8 9 1 1 35SR6 7 10 12 29

11/20/2014 1 16 5 11 6 1 3911:10am 4 14 8 14 4 2 42

11/20/2014 JO 1 1 1 3SAR 1 1 2SR2 2 4 1 7SR6 2 6 10 18

TOTAL 254 357 160 15 22 52 7 2 869overall total

wild 611white 175vest 74vest/white 9

In the above table the F2 generation was summarized by counting the apparent different fruit flies. 4 classifications were categorized in the following table. Wild type, white eyes, vestigial, and vestigial and white eyes were counted for each male and each female fruit fly at the end the overall total was given.

The Following tables are all constructed F2 phenotypic ratios and Chi square analysis of the F2 generation.

Phenotypes Expected Overall

Phenotypic Ratio

Expected Phenotypic ratio for

Females

Expected Phenotypic Ratio

for Males

Wild Type 6/16 3/8 3/8White Eyes 6/16 3/8 3/8Vestigial Wings 2/16 1/8 1/8

White eyes; vestigial wings 2/16 1/8 1/8

Expected Overall Phenotypic Ratio

Phenotypic Class

O E O-E (O-E)^2 (O-E)^2/E

Wild type 611 325.875 285.125 81296.26563 249.4707039White eyes 175 325.875 -150.875 22763.26563 69.85275222Vestigial wings

74 108.625 -34.625 1198.890625 11.03696778

White eyes; Vestigial Wings

9 108.625 -99.625 9925.140625 91.3706847

869 Chi Square= 421.7311086

Expected Phenotypic Ratio for Females

Phenotypic Class

O E O-E (O-E)^2 (O-E)^2/E

Wild type 357 133.875 223.125 49784.76563 371.875White eyes 15 133.875 -118.875 14131.26563 105.5556723Vestigial wings

52 44.625 7.375 54.390625 1.218837535

White eyes; Vestigial Wings

2 44.625 -42.625 1816.890625 40.71463585

426 Chi Square= 519.3641457

Expected Phenotypic Ratios for Males

Phenotypic Class

O E O-E (O-E)^2 (O-E)^2/E

Wild type 254 166.125 87.875 7722.015625 46.48316403White eyes 160 166.125 -6.125 37.515625 .22582769Vestigial wings

22 55.375 -33.375 1113.890625 20.11540632

White eyes; Vestigial Wings

7 55.375 -48.375 2340.140625 42.25987585

443 Chi Square= 109.0842739

Discussion

For the given F1 cross the inheritance pattern of the given fruit flies was identified as a white eyes and vestigial wings mutation. Two different traits that carry different genes in each phenotype. As a reference to my chi-square values of my analysis I got 421.731 for the overall p value. 519.364 For male p value and the 109.084 for the female p value analysis. The concluded chi-square analysis proposed that because of the variation between the observed and expected results is due by chance. The chi square analysis suggest that the F2 analysis is not consistent with the phenotypic ratio. Although many of the phenotypic outcomes are seen but the collected data is not accurately statistically being measured.

There is many differences between the expected number and the observed number in regarding to the data collected. In this experiment 1000 fruit flies was not reached and that made have unbalanced the appropriate phenotypic ratios and therefore the following results did not match the chi-square analysis. Although we did not get what we expected for our F2 generation we concluded that the inheritance patterns did not regulate the correct observed and expected results. The ratio’s obtained from the following dihybrid cross concluded that that the F2 generation had a probability of the P crossed mutants being a white eyes and vestigial wings as suggested in our hypothesis.

Although during my fly breeding my group did not reach to 1000 fruit flies and the only problem I could understand is that not getting enough flies in your F2 generation could basically interrupt and could give you a different inaccurate phenotypic ratios which could lead to an uncertain P value.

In this experiment I learned how to review the principles of Mendel’s laws of genetics which included using a punnet square, chi square analysis, and dihybrid crosses. In addition I have learned how to conduct a fruit fly experiment by observing the F1 generation and interbreeding them to yield an F2 generation. With the following techniques I have also learned to analyze the experimental data to create a hypothesis. For this lab I was able to understand how sex linkage genes assort independently and how either male or female can have a higher probability to acquire that gene due to the location of the chromosome. If it was possible I would think of taking this experiment to the next level by studying the F3 generation as well to observe if it creates a new mutant trait where I could study the inheritance patterns and identify the possibility of developing a new trait in each generation and how often a mutant trait occurs.