REVISED genetics fly lab report

Topics: Gene, Allele, Genetics Pages: 9 (1584 words) Published: December 7, 2014
Cassie Browne
Anthony Lulgjuraj
Fly Lab Report
Friday 9:30am
Mutation #620 X Mutation #644
1) The vial labeled Mutation #620 contained female flies that displayed a mutation in eye color. This mutation causes a change in eye pigment from wild type (bright red) to a dark, reddish brown. The males possessed mutation #644. It is a mutation in wing morphology that reduces wing size. A controlled cross was conducted between these two true-breeding mutant flies. Their progeny (F1) being heterozygous for both mutations displayed only wild type phenotypes. These two mutations in Drosophila are both believed to follow an autosomal recessive pattern of inheritance.

Figure 1. Images Drosophila melanogaster with mutations. From left to right, mutation in eye color (e), mutation in wing morphology (w). A controlled cross was performed between a true-breeding fly with the eye color mutation and a true-breeding fly with the wing mutation.

P1

F1

Figure 2. A pedigree showing the pattern of inheritance for a mutation in eye color and a mutation in wing morphology. Both mutations are recessive and their alleles are represented as e/e; w/w. Symbols with the left half shaded have a mutation in eye color and normal wings. Making the parental female’s genotype e/e; w+/w+. Symbols with the right half shaded have wild type eyes and a mutation with wing morphology. This gives rise to the parental male’s genotype, e+/e+; w/w. All of the F1’s are heterozygous for there genotype, e/e+; w/w+, and display wild type phenotypes.

Table 1. Data collected from observing the phenotypes of the F1 offspring from the controlled cross. All progeny were phenotypically wild type.
F1

Males

Females

Wild Type

15

17

Mutation #620

0

0

Mutation #644

0

0

Other Phenotype

0

0

P1
F1
F1

F2

Figure 3. This pedigree represents the pattern of inheritance in all three generations. Symbols with the left half shaded just have an eye color mutation. Symbols with the right half shaded just have wing mutation. Symbols that are fully shaded display both mutations. The parental female’s genotype is e/e; w+/w+ and the parental male’s genotype is e+/e+; w/w. All the F1 genotypes are heterozygous e/e+; w/w+ and displayed wild type phenotypes. The F1’s were self-crossed and the progeny phenotypes were wild type, eye color mutation, wing mutation and both mutations. The F2 genotype for wild type is e+/-; w+/-. The genotypes representing the eye color mutation and wing mutation were e/e; w+/- and e+/-; w/w. The genotype displaying both recessive mutations is e/e; w/w.

Table 2. Data observed from the different phenotypes displayed in the F2 generation. The progeny from the F1 self-cross showed four phenotypes.
F2

Males

Females

Wild Type

9

16

Mutation #620

3

9

Mutation #644

5

2

Other Phenotype

3

1

Table 3. Calculated X^2 values for the F2 generation. The calculated value will be used in a Chi Square analysis to determine if the observed values are consistent with the expected values. F2

Expected
(E)
27

Observed
(O)
25

(O-E)

(O-E)^2

Wild Type

Expected
Fraction
(9/16)

2

4

(O-E)^2/
E
0.1481

Mutation #620

(3/16)

9

12

-3

9

1

Mutation #644

(3/16)

9

7

2

4

0.4444

Other Phenotype

(1/16)

3

4

-1

1

0.3333

Total

1.9258

The mutation in the eye pigment color and the mutation that reduced wing size both displayed a recessive pattern of inheritance. It is also believed that these genes are found on the autosomes of Drosophila melanogaster. The model autosomal recessive pattern of inheritance directly correlated with the data collected from the cross between these two mutations. The calculated Chi Square value was 1.9258. Which is under the 2.366 cut-off value confirming that the observed data is consistent with the expected. Therefore, the Chi Square analysis supports the recessive...
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