1. Simon Lin
Biology SL
Period 7
January 21, 2010
Biology Fly Lab
Background Information
Thomas Hunt Morgan, an American geneticist and embryologist. He was in
Columbia University and founder of the Fly Room. His experiments are based of using
fruit flies, called Drosophila melanogaster, and being able to demonstrate that genes are
carried on chromosomes to the next generation. Morgan bred a white-eyed male fly with
a red-eyed female. All the offspring produced both male and female, which both had red
eyes. Later he bred the offspring male and female, which resulted that some offspring
ended up with red eyes and some with white eyes. All of the flies with white eyes were
males. In conclusion he found out the first evidence of a sex-linked recessive trait. By
using his studies and experiment support, he won the Nobel Prize in Medicine in 1933.
Introduction
Throughout the lab, the experiments are to be done online. The online lab will
provide the different types of fruit flies that are available for the experiment. The
purpose of the lab is to mate different flies with the “wild type”, which is known as the
normal flies, and find a mate that traits are inherited. The types that are to be found are:
Dominant allele
Recessive allele
Dominant sex-linked allele
Recessive sex-linked allele
Dominant lethal allele.

2. Dominant Allele
Parents: Wild eye + Lobe eye
Lw Lw
Lw Lw
Offspring 1: Lobe eye
ww Lw
Lw LL
Offspring 2: Lobe eye & Wild eye
Conclusion
Two different types of fruit fly, lobed-eye fruit fly and wild fruit fly. To be a dominant
allele, the parents must be homozygous, nothing mixed to see the result. In which when
the parents mated, the 1st
generation only showed lobed-eye fruit flies meaning that the
allele of lobed eye dominates over wild fruit flies. However before both of the flies were
homozygous, but when both of it mate, the offspring it creates are heterozygous. When
the 1st
offspring mated together, it’ll create 2nd
offspring of 25% Wild fruit flies, and 75%
Lobe-eye fruit flies. It shows that when the two heterozygous fruit flies mated most of it
will be lobe-eye but some will come back to normal, which it was hidden away in the 1st
offspring. Simply when the trait is dominant it will appear more than the other trait.
W W
L
L
w L
w
L
Phenotype: Lobe
Genotype: 100% Lobe (Heterozygous)
Chi-Square Analysis = 0.000000
Observed = 984/1000
Hypothesis = 1.00000
Degree of freedom = 0
Level of Significance = 1.00000
Do Not Reject You Hypothesis
Phenotype: Lobe, Wild
Genotype: 50% Lobe (Heterozygous) 25% Lobe
(Homozygous) 25% Wild (Homozygous)
Chi-Square Analysis = 0.1992
Observed = W: 247/1000 L: 717/1000
Hypothesis = W: 1 L: 3
Degree of freedom = 1
Level of Significance = 0.6554
Do Not Reject You Hypothesis

3. Recessive Allele
Parents: Wild eye + Purple eye
Wp Wp
Wp Wp
Offspring 1: Wild eye
WW Wp
Wp pp
Offspring 2: Wild eye & Purple eye
Conclusion
Two different types of fruit fly, Wild eye fruit fly and purple eye fruit fly. To be a
recessive allele, the parents must be homozygous, nothing mixed to see the results. In
which when the parents mated, 1st
generation only showed wild eye fruit flies meaning
that the allele of purple eyes is weaker than the wild eyes, recessive. If purple trait is
recessive it will definitely show in the 2nd
generation of the offspring. In which the data
has shown that purple eye reappeared in the 2nd
offspring, showing that during the 1st
offspring the trait was dominated by Wild eye. Therefore when the 1st
offspring both
heterozygous mated it will create some purple eye fruit flies in their next generation.
Simply when the trait is recessive it won’t show in the 1st
generation, but it will show in
the 2nd
generation of offspring.
W W
P
P
W p
p
W
Phenotype: Wild
Genotype: 100% Wild (Heterozygous)
Chi-Square Analysis = 0.000000
Observed = 1035/1000
Hypothesis = 1.00000
Degree of freedom = 0
Level of Significance = 1.00000
Do Not Reject You Hypothesis
Phenotype: Wild, Purple
Genotype: 50% Wild (Heterozygous) 25% Wild
(Homozygous) 25% Purple (Homozygous)
Chi-Square Analysis = 0.6133
Observed = W: 743 Purple: 262
Hypothesis = W: 3 Purple: 1
Degree of freedom = 1
Level of Significance = 0.4336
Do Not Reject You Hypothesis

4. Dominant Sex-Linked Allele
Parents: Male: Bar eye + Female: Wild eye
XWXB XWY
XWXB XWY
Offspring 1: Male: Wild eye Female: Bar eye
XWXW XWY
XWXB XBY
Offspring 2: Male: Wild & Bar eye
Female: Wild & Bar eye
Conclusion
The male fruit fly has the trait of Bar eye, and the female fruit fly has the trait of wild
eye. To show that bar eye is a dominant sex-link trait, the female has to be a bar eye
when it’s a heterozygous fruit fly and has a trait of bar eye in its gene. As shown in
offspring 1, the female will all inherit the trait of bar eye from due the fact that male fruit
fly has only the bar eye gene. That will be one proof shown. Then in the 2nd
generation
of offspring, half of the male and female will be bar eye since there whenever there is a
bar eye allele it will dominate over the other trait. Therefore Bar eye is a dominant sex-
linked trait.
XB Y
XW
XW
XW Y
XW
XB
Phenotype: Male: Wild Female: Bar
Genotype: Male: 100% Wild (Homozygous)
Female: 100% Bar (Heterozygous)
Chi-Square Analysis = 0.2243
Observed = Female: 484/1000 Male: 509/1000
Hypothesis = Female: 1.0000 Male: 1.0000
Degree of freedom = 1
Level of Significance = 0.6358
Do Not Reject You Hypothesis
Phenotype: Male & Female: Wild & Bar
Genotype: Male: 50% Wild & 50% Bar
(Homozygous) Female: 50% Bar (Heterozygous)
50% Wild (Homozygous)
Chi-Square Analysis = 6.3077
Observed = Female W: 234/1000 B: 272/1000
Male W: 286/1000 B: 248/1000
Hypothesis = Female: 1.0000 Male: 1.0000
Degree of freedom = 3
Level of Significance = 0.0976
Do Not Reject You Hypothesis

5. Recessive Sex-Linked Allele
Parents: Male: Tan Body + Female: Wild Body
XTXW XWY
XTXW XWY
Offspring 1: Male: Wild Body Female: Wild Body
XWXW XWY
XWXT XTY
Offspring 2: Male: Wild & Tan Body
Female: Wild Body
Conclusion
The male fruit fly eye has the Tan body allele, and the female fruit fly has the wild body
allele. To show that Tan body is a recessive sex-linked trait, the female will have to still
be wild when there is a Tan body allele in it. As shown in offspring 1, when the female
offspring inherited the allele of the Tan body nothing showed up, which means that wild
body is dominated over the recessive Tan body. Then Looking at the Offspring 2, the
same thing occurred with the female fruit fly, the tan body trait did not show up again.
However it showed up for the male since male only need 1 allele to determine how it is
going to be. Therefore Tan body is a recessive sex-linked trait.
XW
XW
XT Y
YXW
XW
XT
Phenotype: Male: Wild Female: Wild
Genotype: Male: 100% Wild (Homozygous)
Female: 100% Wild (Heterozygous)
Chi-Square Analysis = 0.5392
Observed = Female: 479/1000 Male: 502/1000
Hypothesis = Female: 1.0000 Male: 1.0000
Degree of freedom = 1
Level of Significance = 0.4627
Do Not Reject You Hypothesis
Phenotype: Male: Tan & Wild Female: Wild
Genotype: Male: 50% Wild & 50% Tan
(Homozygous) Female: Wild 50% (Homozygous)
50% (Heterozygous)
Chi-Square Analysis = 4.6103
Observed = Female W: 530/1000
Male W: 302/1000 B: 256/1000
Hypothesis = Female: 2.0000 Male: 1.000 + 1.000
Degree of freedom = 2
Level of Significance = 0.0997
Do Not Reject You Hypothesis

6. Dominant Lethal Allele
Parents: Male: Wild Wings + Female: Curly Wings
WW WW
WC WC
Offspring 1: Wild Wings & Curly Wings
WW WC
WC CC
Offspring 2: Wild Wings
Curly Wings
Conclusion
The two different types of fruit flies, Curly wings fruit fly and Wild wings fruit fly,
shows how dominant lethal allele works. Dominant lethal alleles can’t survive being
homozygous, which in this case curly wings fruit fly can never be homozygous. Also,
being dominant lethal allele, the trait/allele will dominate over the other trait. Offspring
1, A heterozygous Curly wings mated with a homozygous wild wings it creates half Wild
half Curly showing that Curly wings dominate over Wild wings. Dominant lethal allele
will show by the generation of offspring 2. Since the 2 mated fruit flies are Curly wing
heterozygous, it will one point produce a homozygous curly wing. However it will never
survive so as the data show that the ratio between curly to wild is only 2:1, if its not a
W W
W
C
W
W
C
C
Phenotype: Curly & Wild
Genotype: 50% Wild (Homozygous)
50% Curly (Heterozygous)
Chi-Square Analysis = 0.2312
Observed = Wild: 494 Curly: 479
Hypothesis = Wild: 1.0000 Curly: 1.0000
Degree of freedom = 1
Level of Significance = 0.6306
Do Not Reject You Hypothesis
Phenotype: Curly & Wild
Genotype: 25% Wild (Homozygous)
50% Curly (Heterozygous)
Chi-Square Analysis = 0.1969
Observed = Wild: 332 Curly: 684
Hypothesis = Wild: 1.0000 Curly: 2.0000
Degree of freedom = 1
Level of Significance = 0.6573
Do Not Reject You Hypothesis

7. dominant lethal allele the ratio would be 3:1. Only 75% of the offspring will like to
survive. Therefore dominant lethal allele will only be shown by the 2nd
generation when
mating only curly wing fruit flies, and curly wings is a dominant lethal allele.