Download Fruit Fly Sex Linked Virtual Lab

Name: ______________________________________________
Period: ______
Fruit Fly Investigation: Mating Drosophila
melanogaster and Exploring Sex-Linked Traits
Directions: Go to http://www.mhhe.com/biosci/genbio/virtual_labs/BL_15/BL_15.html . Instructions for each
step are given below.
Procedure Part One: Click on the TV/VCR. Watch the short clip on Drosophila melanogaster. Summarize the
video clip below:
Procedure Part Two:
1. Click on the shelf full of vials of fruit flies.
2. Familiarize yourself with male versus
female fruit flies.
3. Before we begin our crosses, write out the genotypes and
phenotypes for each parent purebred fruit fly. Record the data
below.
P Generation
Phenotype: ______
Genotype: _______
Phenotype: ______
Genotype: _______
Phenotype: ______
Genotype: _______
Phenotype: ______
Genotype: _______
4. For our first cross, take a red-eyed purebred female and cross the fly with a red-eyed
purebed male from the P generation. Record the outcome of the cross in Table 1.
5. Then, take a red-eyed purebred female from the F1 generation and cross the fly with a redeyed male from the F1 generation. Record the outcome of the cross in Table 1.
Name: ______________________________________________
Period: ______
Table 1: Drosophila Mating Data: ____________________________________
Phenotype of
Male Parent
Phenotype of
Female Parent
# of RedEyed Male
Offspring
# of RedEyed Female
Offspring
# of WhiteEyed Male
Offspring
# of WhiteEyed Female
Offspring
P Generation
F1 Generation
6. Using a Punnett square, show the P generation cross and the F1 generation cross that you
performed in this section. Remember, these are sex-linked genes.
P Generation Cross
F1 Generation Cross
Phenotype:
Phenotype:
Genotype:
Genotype:
7. Press the Reset button and perform our second cross. In this cross, mate a Purebred red-eyed
female with a purebred white eyed male. Record the outcome of the cross in Table 2.
8. Then, take a red-eyed female from the F1 generation and cross the fly with a red-eyed male from
the F1 generation. Record the outcome of the cross in Table 2.
Table 2: Drosophila Mating Data: ____________________________________
Phenotype of
Male Parent
P Generation
F1 Generation
Phenotype of
Female Parent
# of RedEyed Male
Offspring
# of RedEyed Female
Offspring
# of WhiteEyed Male
Offspring
# of WhiteEyed Female
Offspring
Name: ______________________________________________
Period: ______
9. Using a Punnett square, show the P generation cross and the F1 generation cross that you performed
in this section. Remember, these are sex-linked genes.
P Generation Cross
F1 Generation Cross
Phenotype:
Phenotype:
Genotype:
Genotype:
Analysis: Please answer using complete sentences.
1) Did your Punnet Square data match the data given in the virtual lab for both crosses? Explain.
2) Why are sex-linked traits more prominent in males than in females?
3) Colorblindness results from a sex-linked recessive allele. Determine the genotypes of the offspring that result
from a cross between a color-blind male and a homozygous female who has normal vision. Describe how you
determined the genotypes of the offspring.
4) Hemophilia, a blood disorder in humans, results from a sex-linked recessive allele. Suppose that a daughter of
a mother without the allele and a father with the allele marries a man with hemophilia. What is the probability
that the daughter's children will develop the disease? Describe how you determined the probability.
5) The woman above is extremely nervous about having kids who have hemophilia; she does not want this to
happen. What can you recommend this woman do to make sure that her kids do not get this genetic disorder?
Name: ______________________________________________
Period: ______
Procedure Part Three: Run a Chi Square Test on the genetic crosses done below. Accept or reject the null
hypothesis.
1) A scientist predicts that the kittens born with a congenital birth defect will be 25% based on the hypothesis
that it is caused be a recessive gene in that breed of cat. After surveying several litters, he found that 44 out of
125 kittens had the defect. Is his hypothesis correct?
2) A scientist predicts that the puppies born with a congenital birth defect will be 50% based on the hypothesis
that it is caused be a recessive gene in that breed of dog. After surveying several litters, he found that 67 out of
125 kittens had the defect. Is her hypothesis correct?