Posted: August 24th, 2016
You are working as a work experience student in the CSIRO entomology researching Drosophila. Your supervisor has set you investigating the inheritance of Drosophila using Gene Mapping.
Write a scientific report which shows the results of tasks 1-4 and your analysis of these provided results.
1. In the laboratory you have set up a cross between a 4+V Female and Wild type Male Drosophila.
The 4+V strain is a pure breeding mutant with 4 X-linked recessive genes.
These genes are: Crossveinless Wings cv
Vermillion Eyes v
Yellow Body y
Forked Bristles f
However, the results of your F1 generation all displayed 4+V phenotypes. This indicated that the 4+V female wasn’t a virgin. Unfortunately there isn’t sufficient time for you to repeat your test crosses and score the F2 progeny before you finish your work experience. Produce a punnett square to predict the outcome of the F1 generation showing the 4 X-linked genes to explain why it was known that the 4+V female couldn’t have mated with the wild type males if 4+V phenotypes were observed in the F1 generation. Identify why gene mapping isn’t required to predict the F1 generation.
2. Fortunately, your supervisor has provided you with fly data to analyse. Your supervisor completed the same initial cross and a cross of the F1 flies, which were sibling-mated to produce the F2 generation.
Examine, analyse and report on your supervisor’s raw fly scoring data, which is shown on the following pages. Scoring data was obtained by physically examining each F2 fly and observing if any of the four mutations were present. The supervisor advises you that these results were scored by the previous work experience student who unfortunately couldn’t distinguish the difference between yellow body and wild type bodied flies so there are no scores for the body colour.
She would like you to organise the data and then calculate a gene map to evaluate how accurate the students scoring of the mutant characteristics were.
3. Using a Drosophila Chromosome map predict the outcomes of the F2 generations of these crosses. Your supervisor has provided a spreadsheet to aid you in calculating these percentages. You will need to modify and complete this spreadsheet.
4. Compare the results of your supervisors’ crosses in the F1 & F2 generations with the predicted outcomes. Use a chi-squared (X2) test to compare the predicted results vs observed data.
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