Genetics & Drosophila Melanogaster Lab Report
Background: For two months, you will breed Drosphila melanogaster (fruit flies) and
set up genetic crosses in order to determine the pattern of inheritance of certain mutant
traits. The traits for which we will examine the pattern of inheritance are apterous
(wingless), vestigial (crippled wings) or white eyes. These are all mutant strains. The
normal condition (winged and red eyes) is referred to as the wild type strain.
Objective: The intial cross mates homozygous mutant fruit flies with homozygous wild
type fruit flies in order to produce an F1 generation of offspring. The F1 offspring mate
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 dominance.
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 your cross.
Calculate the following ratios (can be expressed as a percentage)
F1 offspring:
 Male mutant : female mutant
 Male wild type : female wild type
 Male mutant : male wild type
 Female mutant : female wild type
 Total mutant : total wild type
F2 offspring:
 Male mutant : female mutant
 Male wild type : female wild type
 Male mutant : male wild type
 Female mutant : female wild type
 Total mutant : total wild type
Conclusion:
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.
Offer suggestions and recommendations for future study.
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