student #1 & student #2 1 st period biology mr. teacher
TRANSCRIPT
![Page 1: Student #1 & Student #2 1 st Period Biology Mr. Teacher](https://reader035.vdocument.in/reader035/viewer/2022062511/551b0e145503462e578b5977/html5/thumbnails/1.jpg)
Eye Color Genetics ProjectStudent #1 & Student #2
1st Period BiologyMr. Teacher
![Page 2: Student #1 & Student #2 1 st Period Biology Mr. Teacher](https://reader035.vdocument.in/reader035/viewer/2022062511/551b0e145503462e578b5977/html5/thumbnails/2.jpg)
Student #1 – blue eyes
Father – blue eyes Mother – green eyes
Paternal Grandparents
Grandfather –green eyes
Grandmother –blue eyes
Maternal Grandparents
Grandmother –green eyes
Grandfather –brown eyes
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Punnett Square for Student #1Student #1’s Mother has allele combination bbGG and Father has bbgg.
Brown/Blue b b
b bb bb
b bb bb
Green/Hazel G G
g Gg Gg
g Gg Gg
So the offspring (Student #1) is bbGg, which should result in hazel eyes.However, the green/hazel gene has incomplete dominance. This means that the expressed phenotype can be anywhere from pure green to dark hazel depending on the genes given by the parents.
![Page 4: Student #1 & Student #2 1 st Period Biology Mr. Teacher](https://reader035.vdocument.in/reader035/viewer/2022062511/551b0e145503462e578b5977/html5/thumbnails/4.jpg)
Father – brown eyes
Paternal Grandparents Maternal Grandparents
Mother – blue eyes
Student #2 – brown eyes
Grandmother – hazel eyes
Grandfather – blue eyes
Grandmother – brown eyes
Grandfather – brown eyes
![Page 5: Student #1 & Student #2 1 st Period Biology Mr. Teacher](https://reader035.vdocument.in/reader035/viewer/2022062511/551b0e145503462e578b5977/html5/thumbnails/5.jpg)
Punnett Square for Student #2Student #2’s Mother has allele combination bbgg and Father has BBGG.
Brown/Blue b b
B Bb Bb
B Bb Bb
Green/Hazel g g
G Gg Gg
G Gg Gg
So the offspring (Student #2) is BbGg, which results in brown eyes. The dominant phenotype here is brown eyes, as every possible combination results in browneyes.
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Punnett Square for Potential OffspringStudent #1’s allele combination is bbgg, and Student #2’s allele combination is BbGg.Here is the Punnett Square, and the various combinations follow:
Brown/Blue B b
B BB Bb
b Bb bb
Green/Hazel g g
G Gg Gg
g gg gg
Student #1 is homozygous in their gene makeup. Both alleles for each genes are the same (bb and gg). Student #2 is heterozygous in their gene makeup. Student #2 posseses both alleles for each gene (Bb and Gg).
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Punnett Square for Potential OffspringSee the possible combinations of the two genes (brown/blue, green/hazel):
Brown/Blue B b
B BB Bb
b Bb bb
Green/Hazel g g
G Gg Gg
g gg gg
Each brown/blue gene can be paired up with 4 different green/hazel genes. This is repeated with each brown/blue gene. Therefore there are 16 different gene pairs. These are listed on the next slide.
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Possible GenotypesThe 4 brown/blue genes we paired are BB, Bb, Bb, and
bb. These were taken from the Punnett Square.
Number of Genotypes = 16BBGg = 2, BBgg = 2, BbGg = 4, Bbgg = 4, bbGg = 2,
bbgg = 2
Brown/Blue Gene Possible Pairs with Green/Hazel
BB pair BBGg, BBGg, BBgg, BBgg
Bb pair (first) BbGg, BbGg, Bbgg, Bbgg
Bb pair (second) BbGg, BbGg, Bbgg, Bbgg
bb pair bbGg, bbGg, bbgg, bbgg
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Genotype ProbabilitiesNumber of Genotypes = 16
BBGg = 2, BBgg = 2, BbGg = 4, Bbgg = 4, bbGg = 2, bbgg = 2
Probability of BBGg offspring = 2/16 * 100 = 12.5%
Probability of BBgg offspring = 2/16 * 100 = 12.5%
Probability of BbGg offspring = 4/16 * 100 = 25%Probability of Bbgg offspring = 4/16 * 100 = 25%Probability of bbGg offsrping = 2/16 * 100 =
12.5%Probatility of bbgg offspring= 2/16 * 100 = 12.5%
Total 100%
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Brown Phenotype Probability
There are 4 genotypes that produce a brown eyed offspring:
• BBGg, BBgg, BbGg, Bbgg
Since brown is dominant over all other colors the presence of a big B allele will automatically give the child brown eyes, regardless of the green/blue gene.
Adding the probabilities for each of the genotypes we get the total probability for the phenotype
• 12.5% + 12.5% + 25% + 25% = 75% probability of having a brown eyed offspring
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Hazel Phenotype ProbabilityFor the green/hazel gene to be shown in a phenotype the brown/blue gene must be bb.
There is one genotype that will give you hazel eyes. Because the gene for green/hazel eyes has incomplete dominance you need a heterozygous genotype for green/hazel to have hazel eyes.
• bbGg
Since there is only one genotype for hazel eyes, the probability for the phenotype is the same as the probability for the genotype.
• bbGg = 12.5% probability of having a hazel eyed offspring
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Green Phenotype Probability
The green phenotype requires a genotype of bbGG. Since this genotype is not represented in our hypothetical offspring, the probability of green phenotype is 0%.
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Blue Phenotype Probability
The only genotype that produces a blue phenotype is bbgg.
Because of this the probability of the genotype is the same as the probability of the phenotype.
12.5% probability child will have blue eyes.
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Conclusion!
It is most probable that if Student #1 and Student #2 were to create an offspring, that offspring would have the phenotype of brown eyes. It is impossible for their offspring to have green eyes.