Fruit Fly Investigation: Mating Drosophila Melanogaster and Exploring Sex-Linked Traits

Name: ______Period: ______

Fruit Fly Investigation: Mating Drosophila melanogaster and Exploring Sex-Linked Traits

Directions: Go to . 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.

1. Before we begin our crosses, write out the genotypes and phenotypes for each parent purebred fruit fly. Record the data below. P Generation

Phenotype: ______Phenotype: ______Phenotype: ______Phenotype: ______

Genotype: ______Genotype: ______Genotype: ______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 red-eyed male from the F1 generation. Record the outcome of the cross in Table 1.

Table 1: Drosophila Mating Data: ______

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 CrossF1 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: ______

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 CrossF1 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?

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?