Fruit Fly Lab Report
Genetics of Organisms
Nicole Ryan
AP Biology 2/2/15 Block 1
Introduction and Background
Drosophila melanogaster or more commonly referred to as “fruit flies” have been used for genetic research for over 100 years. During his time at Harvard university, Charles W. Woodworth is credited with being the first to suggest fruit flies be used for genetic research. A century later, fruit flies are the most widely used eukaryotic organism for genetic research (Drosophila). Their ease of use and rapid rate of reproduction has allowed researchers across the globe further our knowledge of genetics. Measuring only a few millimeters in length, fruit flies take up a fraction of the room of other organisms …show more content…
such as fish or rats that have also been used in such research. The flies are small enough to be compact, yet large enough to be seen in great detail under a dissecting microscope. Due to their size, cost of food and space to house them is extremely low, making them easily accessible to schools and laboratories everywhere.
The entire life cycle of the fruit fly is a mere 30 days, 7-12 days of which are spent maturing. 12-15 hours after eggs are laid, larvae emerge for 4 days to grow and feed on rotting fruit (which their eggs were laid on) before undergoing a 4 day metamorphosis after which they are adults. The rest of their adult lives are spent eating and mating (Fruit Fly). Females are able to mate as soon as 12-18 hours after the 4 day metamorphosis. Differentiating male and female flies is quite simple; males (left) have sex combs which look like small black dots on their front legs and have fewer dark lines across their abdomen. Females (right) are typically larger and have dark stripes across the abdomen and have an ovipositor extending from the lower abdomen (Lab Seven).
Today, fruit flies are being used in stem cell research of germline cells. These highly vital germline cells become gametes and carry on the evolution of a species. Researchers at the University of Utah have been studying how germ stem cells protect themselves from becoming somatic cells using fruit flies. It all began in 1922 at Massachusetts Institute of Technology where Ruth Lehmann discovered a gene she named “oskar”. Oskar is responsible for adding a vital protein to the plasma of the germ stem cell that when inactive inhibits the production of germ cells. When it is turned on, germ cells are produced and kept as stem cells through “extreme transcriptional repression”. During this process, DNA is inhibited from being transcribed to RNA which in turn means no gene expression. This research is delving into the specifics of stem cells which are suspected to hold treatments for many diseases (Scudelari). While our lab wasn’t investigating the mechanics of stem cell development, we studied the inheritance of traits though generations of flies. Our objective was to see the different patterns of inheritance that genes can take. To have results as close to expected as possible we kept temperature, food and light constant throughout all tests as controls and let the mating and passing of traits be the variable. Keeping all other factors constant we hypothesized that if cross A showed monohybrid inheritance it would have a 1:2:1 ratio, dihybrid crosses would have a 9:3:3:1 ratio and sex linked inheritance would show a 1:1:1:1 ratio of inheritance.
Materials
Fruit Flies (Drosophila Melanogaster)
Cross A: Sepia female x Wild male
Cross B: Vestigial female x Sepia male
Cross C: White female Wild male
Colored tape
Petri dishes
Fruit fly blue media
Flynap
Plastic vials (with foam stoppers)
Microscopes
Paint Brushes
Funnels
“Morgue”
Ice packs
Procedure
1. Obtain a vial of F1 generation flies (either cross A,B, or C and make sure to label the vials as such). The first objective is to remove the flies from the vial without having them fly away. To prevent this, wedge a wand that has been dipped in fly nap between the foam stopper and the vial so that it reaches into the vial to anesthetize the flies. To help immobilize them, placing the vials in a cool location or on an ice pack can help to calm them as they are reliant on environmental factors.
2. After the flies have been anesthetized, remove them from the vials and place them in petri dishes with labels matching the vials they came from to avoid confusion. To remove the immobilized flies from the vial, it is important to be gentle and avoid crushing any flies. The majority of the flies should fall from the vial when it is inverted, but to remove any that are left, a paintbrush can be very useful to move them without causing them any harm.
3. Once the flies are in petri dishes, place them on ice packs to prevent the flies from waking up during counting. Place the ice pack and petri dish under a dissecting microscope. With the help of the microscope, record the sex and phenotype of all flies. To maneuver the flies within the petri dish, use a paint brush to avoid harm. The characteristics of sexing flies is described in the introduction on page 2.
4. Once the flies have been sorted by sex and phenotype, prepare the vials for the F2 generation. Mix equal parts dry food and water and let it set in the vial. Make sure to label the vial with the phenotypes of each parent of the cross.
5.
Once the vials are prepared, begin placing in pairs of male and female flies into the correctly labeled vials. Use paint brushes for moving flies if necessary. Cap these vials and place them in a warm area. These flies will mate and produce the F2 generation
6. After the F2 vials have been sitting for approximately 10-12 days, remove the adult flies. By this time the flies will have mated and the female will have laid her eggs. Removing the adults will prevent F1 flies from mating with F2 offspring. To do this, carefully use Flynap (technique as described in step 1), being aware that fly larvae are more sensitive and may be fatally harmed by “over-napping”. Remove the flies by inverting the vial and placing the adult F1 flies in the “morgue” (a jar containing alcohol or baby oil). Then close the vial and allow it to sit for another 12-15 days.
7. After 12-15 days have passed, record the sex and phenotype of all adult flies. As described in steps 1-3 Flynap will be used to anesthetize the flies before they are removed from the vials to be put into petri dishes for counting. Once all of the flies have been counted and recorded, place them into the “morgue” and dispose of all …show more content…
vials.
Results
F1 Results:
Cross A – Wild Male x Sepia Female
EE x ee
E
E
e
Ee
Ee e Ee
Ee
E – Wild eyes e – Sepia eyes
Cross B – Sepia eye normal wing male x Wild eye vestigial wing female eeFF x EEff
Ef
Ef
Ef
Ef
eF
EeFf
EeFf
EeFf
EeFf eF EeFf
EeFf
EeFf
EeFf
eF
EeFf
EeFf
EeFf
EeFf eF EeFf
EeFf
EeFf
EeFf
E – Wild eyes e – Sepia eyes
F – Normal wings f – Vestigial Wings
Cross C – Wild male x White female
XeXe x XEY
Xe
Xe
XE
XEXe
XEXe
Y
XeY
XeY
E – Wild eyes e – White eyes
F2 results:
Cross A – Wild male x Wild female
Ee x Ee
E e E
EE
Ee e Ee ee E – Wild eyes e – Sepia eyes
Chi-square Analysis
Phenotype
# Observed
# Expected
(o-e)
(o-e)2
(o-e)2/e
Wild eyes
256
260
-4
16
.0615
Sepia eyes
91
87
4
16
.183
Chi-square Value
.25
Null Hypothesis: If a monohybrid cross is performed between two fruit flies that are both heterozygous for eye color, the expected offspring counts should be in a 3 wild: 1 sepia ratio and would have a chi square value less than 5.99.
Cross B – Wild eye/ Normal wing male x Wild eye/ Normal wing female
EeFf x EeFf
EF
Ef
eF ef EF
EEFF
EEFf
EeFF
EeFf
Ef
EEFf
EEff
EeFf
Eeff
eF
EeFF
EeFf eeFF eeFf ef EeFf
Eeff
eeFf eeff F- Normal wings f- Vestigial wings
E- Wild eyes e- sepia eyes
Chi-square Analysis
Null Hypothesis: If a dihybrid cross is performed between two fruit flies, one being homozygous dominant for normal wings and heterozygous for eye color and the other being heterozygous for wing type and eye color means the expected offspring counts should be in a 9 wild eye normal wing: 3 wild eye vestigial wing: 3 sepia eye normal wing: 1 sepia eye vestigial wing ratio and would have a chi square value less than 7.82.
Cross C – White male x Wild female
XEXe x XeY
XE
Xe
Xe
XEXe
XeXe
Y
XEY
XeY
E- Wild eyes e- White eyes
Chi-square Analysis
Phenotype
# Observed
# Expected
(o-e)
(o-e)2
(o-e)2/e
White male
106
135
-29
841
6.23
White female
162
135
27
729
5.4
Wild male
99
135
-36
-1296
9.6
Wild female
171
135
36
1296
9.6
Chi-square Value
30.83
Null Hypothesis: If a sex linked cross is performed between two fruit flies, the male being dominant and the female being heterozygous the expected offspring counts should be in a 1 white male: 1 white female: 1 wild male: 1 wild female ratio and would have a chi square value less than 7.82.
Class Totals:
Cross A – Wild male x Wild female
Chi-square Analysis
Null Hypothesis: If a monohybrid cross is performed between two fruit flies that are both heterozygous for eye color, the expected offspring counts should be in a 3 wild: 1 sepia ratio and would have a chi square value less than 5.99.
Cross B – Wild/Normal wing male x Wild/Normal female
Chi-square Analysis
Phenotype
# Observed
# Expected
(o-e)
(o-e)2
(o-e)2/e
Wild/Normal wing
1630
1473
157
24649
16.73
Wild/Vestigial wing
275
491
-216
46656
95.02
Sepia/Normal wing
606
491
115
13225
26.93
Sepia/Vestigial wing
108
164
-56
3136
19.12
Chi-square Value
157.8
Null hypothesis: If a dihybrid cross is performed between two fruit flies, one being homozygous dominant for normal wings and heterozygous for eye color and the other being heterozygous for wing type and eye color means the expected offspring counts should be in a 9 wild eye normal wing: 3 wild eye vestigial wing: 3 sepia eye normal wing: 1 sepia eye vestigial wing ratio and would have a chi square value less than 7.82.
Cross C – White male x Wild female
Phenotype
BL 1
BL 2
BL 3
BL 4
Total (2949)
White Male
106
127
188
190
611
White Female
162
147
191
284
784
Wild Male
99
145
207
218
669
Wild Female
172
196
194
324
885
Chi-square Analysis
Null Hypothesis: If a sex linked cross is performed between two fruit flies, the male being dominant and the female being heterozygous the expected offspring counts should be in a 1 white male: 1 white female: 1 wild male: 1 wild female ratio and would have a chi square value below 7.82.
Critical Values of Chi-Square Distribution
Probability
Degrees of Freedom
1
2
3
4
5
0.05
3.84
5.99
7.82
9.49
11.1
Analysis and Discussion The chi-square analysis of the data determines whether or not the data is close enough to the expected values to be considered usable.
The number acquired through the use of the equation is compared to the critical values table to verify or deny the null hypothesis. If the value is equal to or below that of the chart then the hypothesis is valid, if it is above the critical value then it is invalid. The null hypothesis for cross A was valid while the hypotheses for crosses B and C were invalid. (See Punnett squares, Chi-square analysis and null hypotheses located on pages 6-10) For this lab, the use of virgin flies was vital to producing accurate data. Since female fruit flies have the ability to store semen in their ovipositor, eggs can be fertilized with semen from any number of males that she has mated with. Because of this the use of virgin flies in the parental generation ensured that the offspring were products of the male and female of that cross with no contamination from other male flies. However, virgin flies were not required in the F1 cross because they were the only flies we had and would be crossed with each other anyway.
Conclusions The data collected for the F2 generation included a wide range of outcomes. The null hypothesis for cross A for both the block and class data could be accepted as its values of .25 (block 1 data) and .37 (class total data) as they fell below the maximum of 5.99 for 2 degrees of freedom. On the other hand the null hypotheses for crosses B and C were invalid. Cross B’s values fell at 282.6 (block 1 data) and 157.8 (class total data) which are both well above he critical value of 7.82. Cross C’s data fella at 30.84 (block 1 data) and 60.54 (class total data) which are closer than the numbers from cross B but still much above 7.82. These results point to errors in the procedure of the lab. Hundreds of errors could have occurred such as counting errors, discrepancies in techniques and human error. One absolute error that block 1 ran into was being supplied the wrong flies from cross B. As stated, the numbers for this cross were much higher than all other crosses. Shown in the data table (see page 7) are the result for this cross which included no vestigial winged flies. The flies for this cross were supposed to be carries for the recessive trait of vestigial wings but after the cross it became apparent that this was not the case, and that we had been supplied the wrong flies.
Aside from being supplied the wrong flies, more caution and close inspection during the counting of the flies could have helped the results of the lab be more accurate. Counting hundreds of flies can become confusing and there is a great possibility in error of counting whether it be misidentifying the sex of a fly or re-counting some. Having fewer flies per petri dish could help to eliminate some confusion along with a well-organized labeling system to prevent counting the same dish twice. While the data did not fully support our hypothesis, it did support cross A in that it should have a 1:2:1 ratio and a chi square value less than 5.99, which it did. Overall the experiment was a success in that we determined which traits were determined by which modes of inheritance.
Works Cited
"Drosophila Melanogaster." Wikipedia. Wikimedia Foundation, n.d. Web. 01 Feb. 2015.
"The Fruit Fly and Genetics." The Fruit Fly and Genetics. N.p., n.d. Web. 02 Feb. 2015.
“Lab Seven: Genetics of Organisms” Biology Lab Manual College Entrance Examination Board, 2001. Princeton NJ
Scudelari, Megan. "Perfect Balance." hhmi bulletin 28.1 (2015): 20-23. Print.
Nicole Ryan
AP Biology 2/2/15 Block 1
Introduction and Background
Drosophila melanogaster or more commonly referred to as “fruit flies” have been used for genetic research for over 100 years. During his time at Harvard university, Charles W. Woodworth is credited with being the first to suggest fruit flies be used for genetic research. A century later, fruit flies are the most widely used eukaryotic organism for genetic research (Drosophila). Their ease of use and rapid rate of reproduction has allowed researchers across the globe further our knowledge of genetics. Measuring only a few millimeters in length, fruit flies take up a fraction of the room of other organisms …show more content…
such as fish or rats that have also been used in such research. The flies are small enough to be compact, yet large enough to be seen in great detail under a dissecting microscope. Due to their size, cost of food and space to house them is extremely low, making them easily accessible to schools and laboratories everywhere.
The entire life cycle of the fruit fly is a mere 30 days, 7-12 days of which are spent maturing. 12-15 hours after eggs are laid, larvae emerge for 4 days to grow and feed on rotting fruit (which their eggs were laid on) before undergoing a 4 day metamorphosis after which they are adults. The rest of their adult lives are spent eating and mating (Fruit Fly). Females are able to mate as soon as 12-18 hours after the 4 day metamorphosis. Differentiating male and female flies is quite simple; males (left) have sex combs which look like small black dots on their front legs and have fewer dark lines across their abdomen. Females (right) are typically larger and have dark stripes across the abdomen and have an ovipositor extending from the lower abdomen (Lab Seven).
Today, fruit flies are being used in stem cell research of germline cells. These highly vital germline cells become gametes and carry on the evolution of a species. Researchers at the University of Utah have been studying how germ stem cells protect themselves from becoming somatic cells using fruit flies. It all began in 1922 at Massachusetts Institute of Technology where Ruth Lehmann discovered a gene she named “oskar”. Oskar is responsible for adding a vital protein to the plasma of the germ stem cell that when inactive inhibits the production of germ cells. When it is turned on, germ cells are produced and kept as stem cells through “extreme transcriptional repression”. During this process, DNA is inhibited from being transcribed to RNA which in turn means no gene expression. This research is delving into the specifics of stem cells which are suspected to hold treatments for many diseases (Scudelari). While our lab wasn’t investigating the mechanics of stem cell development, we studied the inheritance of traits though generations of flies. Our objective was to see the different patterns of inheritance that genes can take. To have results as close to expected as possible we kept temperature, food and light constant throughout all tests as controls and let the mating and passing of traits be the variable. Keeping all other factors constant we hypothesized that if cross A showed monohybrid inheritance it would have a 1:2:1 ratio, dihybrid crosses would have a 9:3:3:1 ratio and sex linked inheritance would show a 1:1:1:1 ratio of inheritance.
Materials
Fruit Flies (Drosophila Melanogaster)
Cross A: Sepia female x Wild male
Cross B: Vestigial female x Sepia male
Cross C: White female Wild male
Colored tape
Petri dishes
Fruit fly blue media
Flynap
Plastic vials (with foam stoppers)
Microscopes
Paint Brushes
Funnels
“Morgue”
Ice packs
Procedure
1. Obtain a vial of F1 generation flies (either cross A,B, or C and make sure to label the vials as such). The first objective is to remove the flies from the vial without having them fly away. To prevent this, wedge a wand that has been dipped in fly nap between the foam stopper and the vial so that it reaches into the vial to anesthetize the flies. To help immobilize them, placing the vials in a cool location or on an ice pack can help to calm them as they are reliant on environmental factors.
2. After the flies have been anesthetized, remove them from the vials and place them in petri dishes with labels matching the vials they came from to avoid confusion. To remove the immobilized flies from the vial, it is important to be gentle and avoid crushing any flies. The majority of the flies should fall from the vial when it is inverted, but to remove any that are left, a paintbrush can be very useful to move them without causing them any harm.
3. Once the flies are in petri dishes, place them on ice packs to prevent the flies from waking up during counting. Place the ice pack and petri dish under a dissecting microscope. With the help of the microscope, record the sex and phenotype of all flies. To maneuver the flies within the petri dish, use a paint brush to avoid harm. The characteristics of sexing flies is described in the introduction on page 2.
4. Once the flies have been sorted by sex and phenotype, prepare the vials for the F2 generation. Mix equal parts dry food and water and let it set in the vial. Make sure to label the vial with the phenotypes of each parent of the cross.
5.
Once the vials are prepared, begin placing in pairs of male and female flies into the correctly labeled vials. Use paint brushes for moving flies if necessary. Cap these vials and place them in a warm area. These flies will mate and produce the F2 generation
6. After the F2 vials have been sitting for approximately 10-12 days, remove the adult flies. By this time the flies will have mated and the female will have laid her eggs. Removing the adults will prevent F1 flies from mating with F2 offspring. To do this, carefully use Flynap (technique as described in step 1), being aware that fly larvae are more sensitive and may be fatally harmed by “over-napping”. Remove the flies by inverting the vial and placing the adult F1 flies in the “morgue” (a jar containing alcohol or baby oil). Then close the vial and allow it to sit for another 12-15 days.
7. After 12-15 days have passed, record the sex and phenotype of all adult flies. As described in steps 1-3 Flynap will be used to anesthetize the flies before they are removed from the vials to be put into petri dishes for counting. Once all of the flies have been counted and recorded, place them into the “morgue” and dispose of all …show more content…
vials.
Results
F1 Results:
Cross A – Wild Male x Sepia Female
EE x ee
E
E
e
Ee
Ee e Ee
Ee
E – Wild eyes e – Sepia eyes
Cross B – Sepia eye normal wing male x Wild eye vestigial wing female eeFF x EEff
Ef
Ef
Ef
Ef
eF
EeFf
EeFf
EeFf
EeFf eF EeFf
EeFf
EeFf
EeFf
eF
EeFf
EeFf
EeFf
EeFf eF EeFf
EeFf
EeFf
EeFf
E – Wild eyes e – Sepia eyes
F – Normal wings f – Vestigial Wings
Cross C – Wild male x White female
XeXe x XEY
Xe
Xe
XE
XEXe
XEXe
Y
XeY
XeY
E – Wild eyes e – White eyes
F2 results:
Cross A – Wild male x Wild female
Ee x Ee
E e E
EE
Ee e Ee ee E – Wild eyes e – Sepia eyes
Chi-square Analysis
Phenotype
# Observed
# Expected
(o-e)
(o-e)2
(o-e)2/e
Wild eyes
256
260
-4
16
.0615
Sepia eyes
91
87
4
16
.183
Chi-square Value
.25
Null Hypothesis: If a monohybrid cross is performed between two fruit flies that are both heterozygous for eye color, the expected offspring counts should be in a 3 wild: 1 sepia ratio and would have a chi square value less than 5.99.
Cross B – Wild eye/ Normal wing male x Wild eye/ Normal wing female
EeFf x EeFf
EF
Ef
eF ef EF
EEFF
EEFf
EeFF
EeFf
Ef
EEFf
EEff
EeFf
Eeff
eF
EeFF
EeFf eeFF eeFf ef EeFf
Eeff
eeFf eeff F- Normal wings f- Vestigial wings
E- Wild eyes e- sepia eyes
Chi-square Analysis
Null Hypothesis: If a dihybrid cross is performed between two fruit flies, one being homozygous dominant for normal wings and heterozygous for eye color and the other being heterozygous for wing type and eye color means the expected offspring counts should be in a 9 wild eye normal wing: 3 wild eye vestigial wing: 3 sepia eye normal wing: 1 sepia eye vestigial wing ratio and would have a chi square value less than 7.82.
Cross C – White male x Wild female
XEXe x XeY
XE
Xe
Xe
XEXe
XeXe
Y
XEY
XeY
E- Wild eyes e- White eyes
Chi-square Analysis
Phenotype
# Observed
# Expected
(o-e)
(o-e)2
(o-e)2/e
White male
106
135
-29
841
6.23
White female
162
135
27
729
5.4
Wild male
99
135
-36
-1296
9.6
Wild female
171
135
36
1296
9.6
Chi-square Value
30.83
Null Hypothesis: If a sex linked cross is performed between two fruit flies, the male being dominant and the female being heterozygous the expected offspring counts should be in a 1 white male: 1 white female: 1 wild male: 1 wild female ratio and would have a chi square value less than 7.82.
Class Totals:
Cross A – Wild male x Wild female
Chi-square Analysis
Null Hypothesis: If a monohybrid cross is performed between two fruit flies that are both heterozygous for eye color, the expected offspring counts should be in a 3 wild: 1 sepia ratio and would have a chi square value less than 5.99.
Cross B – Wild/Normal wing male x Wild/Normal female
Chi-square Analysis
Phenotype
# Observed
# Expected
(o-e)
(o-e)2
(o-e)2/e
Wild/Normal wing
1630
1473
157
24649
16.73
Wild/Vestigial wing
275
491
-216
46656
95.02
Sepia/Normal wing
606
491
115
13225
26.93
Sepia/Vestigial wing
108
164
-56
3136
19.12
Chi-square Value
157.8
Null hypothesis: If a dihybrid cross is performed between two fruit flies, one being homozygous dominant for normal wings and heterozygous for eye color and the other being heterozygous for wing type and eye color means the expected offspring counts should be in a 9 wild eye normal wing: 3 wild eye vestigial wing: 3 sepia eye normal wing: 1 sepia eye vestigial wing ratio and would have a chi square value less than 7.82.
Cross C – White male x Wild female
Phenotype
BL 1
BL 2
BL 3
BL 4
Total (2949)
White Male
106
127
188
190
611
White Female
162
147
191
284
784
Wild Male
99
145
207
218
669
Wild Female
172
196
194
324
885
Chi-square Analysis
Null Hypothesis: If a sex linked cross is performed between two fruit flies, the male being dominant and the female being heterozygous the expected offspring counts should be in a 1 white male: 1 white female: 1 wild male: 1 wild female ratio and would have a chi square value below 7.82.
Critical Values of Chi-Square Distribution
Probability
Degrees of Freedom
1
2
3
4
5
0.05
3.84
5.99
7.82
9.49
11.1
Analysis and Discussion The chi-square analysis of the data determines whether or not the data is close enough to the expected values to be considered usable.
The number acquired through the use of the equation is compared to the critical values table to verify or deny the null hypothesis. If the value is equal to or below that of the chart then the hypothesis is valid, if it is above the critical value then it is invalid. The null hypothesis for cross A was valid while the hypotheses for crosses B and C were invalid. (See Punnett squares, Chi-square analysis and null hypotheses located on pages 6-10) For this lab, the use of virgin flies was vital to producing accurate data. Since female fruit flies have the ability to store semen in their ovipositor, eggs can be fertilized with semen from any number of males that she has mated with. Because of this the use of virgin flies in the parental generation ensured that the offspring were products of the male and female of that cross with no contamination from other male flies. However, virgin flies were not required in the F1 cross because they were the only flies we had and would be crossed with each other anyway.
Conclusions The data collected for the F2 generation included a wide range of outcomes. The null hypothesis for cross A for both the block and class data could be accepted as its values of .25 (block 1 data) and .37 (class total data) as they fell below the maximum of 5.99 for 2 degrees of freedom. On the other hand the null hypotheses for crosses B and C were invalid. Cross B’s values fell at 282.6 (block 1 data) and 157.8 (class total data) which are both well above he critical value of 7.82. Cross C’s data fella at 30.84 (block 1 data) and 60.54 (class total data) which are closer than the numbers from cross B but still much above 7.82. These results point to errors in the procedure of the lab. Hundreds of errors could have occurred such as counting errors, discrepancies in techniques and human error. One absolute error that block 1 ran into was being supplied the wrong flies from cross B. As stated, the numbers for this cross were much higher than all other crosses. Shown in the data table (see page 7) are the result for this cross which included no vestigial winged flies. The flies for this cross were supposed to be carries for the recessive trait of vestigial wings but after the cross it became apparent that this was not the case, and that we had been supplied the wrong flies.
Aside from being supplied the wrong flies, more caution and close inspection during the counting of the flies could have helped the results of the lab be more accurate. Counting hundreds of flies can become confusing and there is a great possibility in error of counting whether it be misidentifying the sex of a fly or re-counting some. Having fewer flies per petri dish could help to eliminate some confusion along with a well-organized labeling system to prevent counting the same dish twice. While the data did not fully support our hypothesis, it did support cross A in that it should have a 1:2:1 ratio and a chi square value less than 5.99, which it did. Overall the experiment was a success in that we determined which traits were determined by which modes of inheritance.
Works Cited
"Drosophila Melanogaster." Wikipedia. Wikimedia Foundation, n.d. Web. 01 Feb. 2015.
"The Fruit Fly and Genetics." The Fruit Fly and Genetics. N.p., n.d. Web. 02 Feb. 2015.
“Lab Seven: Genetics of Organisms” Biology Lab Manual College Entrance Examination Board, 2001. Princeton NJ
Scudelari, Megan. "Perfect Balance." hhmi bulletin 28.1 (2015): 20-23. Print.