Genetics & Drosophila Melanogaster Lab
Report
Background: For the past two months, you have been breeding Drosphila
melanogaster (fruit flies) and setting up genetic crosses in order to apply basic
genetic principles. The trait for which we have examined the pattern of
inheritance is apterous (wingless). The apterous (wingless) fruit flies are mutant
strains, and the normal condition (winged) is referred to as the wild type strain.
Objective: The intial cross mated mutant (apterous) fruit flies with wild type fruit
flies in order to produce an F1 generation of offspring. The F1 offspring were
mated with each other in order to produce an F2 generation. This results in
sufficient data to determine which trait is dominant or recessive, and if the pattern
of inheritance is autosomal or sex-linked.
Assignment: You will complete a lab report that includes a title, introduction
experimental design, procedure, results, and conclusion. The sections must
include the following information.
Introduction:
Part I: Background information about Drosophila melanogaster
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Information about the structure of Drosophila melanogaster.
Information about the life cycle of Drosophila melanogaster.
Information about sex markers and sex characteristics of Drosophila
melanogaster.
Diagrams of male and female mutant flies. (may include diagrams in
experimental design)
Diagrams of male and female wild type flies.
Information about laboratory culturing of Drosophila melaongaster.
Part II: Genetic applications
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Define autosomal, sex-linkage, dominant, recessive, incomplete dominant.
Statement of a rationale: in order to determine patterns of inheritance and
support basic genetic rules
Statement of purpose: in order to determine patterns of inheritance for the
mutant apterous (wingless) strain in fruit flies
Hypothesis: Predict the % of offspring that will exhibit the dominant and
recessive trait in both the F1 generation and F2 generation, based on whether
the trait is autosomal or sex-linked.
Experimental Design:
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Show phenotypes and genotypes of P1 cross, and then the F1 cross.
You may include diagrams of fruit flies as part of your experimental design
List constant conditions for this experiment
Procedure:
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List the steps necessary to set up each cross.
List the method used to count and record characteristics of fruit flies.
Important: Tell the dates when each of these steps was completed.
Results:
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Create data tables of the numbers of resulting offspring that exhibit the
dominant and recessive trait from each cross.
Calculate the following percentages…
F1 offspring
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% mutant & % wild type (of only males)
% mutant & % wild type (of only females)
% mutant & % wild type (of all flies)
F2 offspring
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% mutant & % wild type (of only males)
% mutant & % wild type (of only females)
% mutant & % wild type (of all flies)
Conclusion:
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Tell which trait is dominant and which trait is recessive or if the pattern shows
incomplete dominance.
Tell if the trait is sex-linked or autosomal.
Site your data to explain your reasoning.
Show Punnett squares for the P1 and F1 crosses.
Compare the actual percentage (from the crosses) to that of the predicted
percentages as derived from the Punnett Square.
Offer suggestions and recommendations for future study.