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Heredity Lab

Last updated over 7 years ago
20 questions
Note from the author:
A Lab investigation using Drosophila flies
Overview: Fruit flies—the genetic whipping boy. Fly genetics are a huge part of the field,
the tiny little Drosophila melanogaster providing aspiring geneticists with over a century of good
times. And flies are also a royal pain in the butt to work with. Especially if you’re new at it.
So let’s use the benefits of the modern age and perform our fly lab squarely within the
boundaries of cyberspace. Ready? Good. Let’s go.
Directions:
1. Sign in and log on to your computer. Open the internet browser and go to the
following website: http://www.sciencecourseware.org/vcise/drosophila/
2. Click the “”Enter as a Guest” option.
3. And here we are in our virtual lab. One very important thing: DO NOT BACK
OUT OF THIS PAGE UNTIL YOU ARE COMPLETELY DONE!!! Or you will
have to start over.
4. The first order of business: you will need to order your fruit flies. Click on the
computer and use the “Order Flies” icon. We are going to perform three different
crosses. For each one, you will need to order the correct flies:
a. Cross 1: Cross a sepia eyed male with a wild type (red eyed) female.
b. Cross 2: Cross a sepia eyed, normal wing male with a wild type eyes, vestigial
wing female.
c. Cross 3: Cross a wild type male with a white eyed female.
5. After ordering your flies, you will have to work through the lab until you eventually
have sorted your F1 progeny. Make sure you record all of the necessary data in your
data table.
6. After you have recorded the data, you will need to establish a cross between
members of your F1 generation. To do this, click on the piles of sorted flies to
zoom in. Then click the “Use in New Mating” button. Do this for both a male and
a female. Then return to your lab. Click on the mating jar.
7. Sort your progeny and record the necessary data in the F2 data table.
8. After you collect F2 data, clean out your incubator by clicking on the small trash can
next to it. This resets your lab for the next cross.
9. Now that you have the F2 data, you can begin to formulate some conclusions about
the mode of inheritance for the traits you are looking at. Briefly comment on what
you believe the mode of inheritance to be. Address the following points in your
conclusion:
a. What is the approximate phenotypic ratio shown in the F2 generation?
b. Does the gender of the flies seem to affect the inheritance of the traits in the
cross?
c. Propose a hypothetical mode of inheritance for your given traits.
10. Congratulations. The only thing left to do is your other two crosses. To order new
flies, simply click on the computer and repeat
11. When you have completed all of the crosses, you may move on to the analysis
section of the lab.
12. I’m proud of you. Really I am.
1

Cross 1: P= sepia male * wild type female
Table 1- Phenotypes of the F1 Generation

1

Table 2- Phenotypes of the F2 Generation

1

Cross 2: P= sepia-eye, normal-wing male * wild type, vestigial wing female
Table 1- Phenotypes of the F1 Generation

1

Table 2- Phenotypes of the F2 Generation
Phenotype Number of Males

1

Cross 3: P= wild type male * white eyed female
Table 1- Phenotypes of the F1 Generation

1

Table 2- Phenotypes of the F2 Generation

1

Cross 4 Your Choice
F1 Generation

1

Cross 4 Your Choice
F2 Generation

Cross 1:
1

1. Describe the parental cross you performed, using genetic symbols.

1

2. Draw a Punnett square to show the possible allelic combinations for this gene in the F1 generation (note, all parental generation flies are homozygous for selected traits). You do not need to keep track of gender unless you believe it is a factor in this cross.

1

3. Identify the genotype the F1 flies should exhibit. Identify the phenotype.
4. Describe the F1 cross you performed and draw a Punnett square to show all the
allelic combinations possible in the F2 generation.
5. Identify the genotype ratio the F2 flies should exhibit. Identify the phenotype ratio.
Compare your experimental results to the predicted ratios.
6. Identify the cross you performed as the following: Monohybrid or Dihybrid,
Autosomal or Sex-Linked, Dominant or recessive mutations. Justify your
conclusion.

CROSS 2
1

1. Describe the parental cross you performed, using genetic symbols.

1

2. Draw a Punnett square to show the possible allelic combinations for this gene in the F1 generation (note, all parental generation flies are homozygous for selected traits). You do not need to keep track of gender unless you believe it is a factor in this cross.

1

3. Identify the genotype the F1 flies should exhibit. Identify the phenotype.
4. Describe the F1 cross you performed and draw a Punnett square to show all the
allelic combinations possible in the F2 generation.
5. Identify the genotype ratio the F2 flies should exhibit. Identify the phenotype ratio.
Compare your experimental results to the predicted ratios.
6. Identify the cross you performed as the following: Monohybrid or Dihybrid,
Autosomal or Sex-Linked, Dominant or recessive mutations. Justify your
conclusion.

CROSS 3
1

1. Describe the parental cross you performed, using genetic symbols.

1

2. Draw a Punnett square to show the possible allelic combinations for this gene in the F1 generation (note, all parental generation flies are homozygous for selected traits). You do not need to keep track of gender unless you believe it is a factor in this cross.

1

3. Identify the genotype the F1 flies should exhibit. Identify the phenotype.
4. Describe the F1 cross you performed and draw a Punnett square to show all the
allelic combinations possible in the F2 generation.
5. Identify the genotype ratio the F2 flies should exhibit. Identify the phenotype ratio.
Compare your experimental results to the predicted ratios.
6. Identify the cross you performed as the following: Monohybrid or Dihybrid,
Autosomal or Sex-Linked, Dominant or recessive mutations. Justify your
conclusion.

Cross 4
1

1. Describe the parental cross you performed, using genetic symbols.

1

2. Draw a Punnett square to show the possible allelic combinations for this gene in the F1 generation (note, all parental generation flies are homozygous for selected traits). You do not need to keep track of gender unless you believe it is a factor in this cross.

1

3. Identify the genotype the F1 flies should exhibit. Identify the phenotype.
4. Describe the F1 cross you performed and draw a Punnett square to show all the
allelic combinations possible in the F2 generation.
5. Identify the genotype ratio the F2 flies should exhibit. Identify the phenotype ratio.
Compare your experimental results to the predicted ratios.
6. Identify the cross you performed as the following: Monohybrid or Dihybrid,
Autosomal or Sex-Linked, Dominant or recessive mutations. Justify your
conclusion.