Download Gummy Bear Genetics

Name: ____________________________________________ Period: __________ Date: _____________
Gummy Bear Genetics
Background: Ursus gelatinous, also known as Gummy bears, are classified as an endangered species. Their reduced
numbers are primarily due to predation by many members of the species Homo sapiens, which devour the Gummy
bears like candy. Several years ago, a captive breeding program was established in order to study this fascinating
species, to increase their population size and ultimately reintroduce them to the wild. Another benefit of the program
was that while in captivity, these Gummy bears were also safe from consumption by the Homo sapiens.
The breeding program began with a purebred male and female bear of each of the four colors (red, green, yellow and
white). Since these bears were normally found in different geographic locations, each pair was kept away from the rest
of the bears in a different wing of the center. Soon enough they started producing their own offspring and the numbers
of Gummy bears started to rise.
Eventually the scientists decided to take a risk and place several purebred bears of each color in a large area where
they could live together. Not long after, something strange began to happen. Several offspring with unusual colored
fur began to show up in the population.
After several generations, they decided to study the inheritance patterns of fur color in the Gummy bears. Initial
results indicated that the new variations may be due to one of the following modes of inheritance between the new
combinations of alleles: complete dominance, incomplete dominance and/or codominance.
Further results led scientists to discover that all of these variations in fur color were controlled by a single gene that has
multiple alleles, just like the ABO blood type in humans. While human blood type is the result of three different
alleles (IA, IB and i), it appears as though fur color in Gummy bears is more complex because it is controlled by four
different alleles, much like fur color in rabbits.
Based upon what the scientists learned so far, they decided to use the following symbols: green = HG, red = HR,
yellow = h’ and clear (without color) = h.
Materials: 1 bag of gummy bear parents and 6 sets of offspring.
Purpose: To determine patterns of inheritance in Gummy bear coat color and parent genotypes from the offspring
phenotypic ratios.
Procedures:
1. Obtain six sets of Gummy bear offspring and one bag of parents.
2. On your table, lay out all six sets of offspring. These are the offspring of the gummy bears in the parent bag.
3. Look at offspring set 1. In the blanks below (under Offspring #1), write out the phenotypes of the offspring that
you have in front of you.
4. Use the Punnett square to the right of Offspring 1 to work backwards and determine the genotypes of the parents.
Be sure to use the symbols HG, HR, h’ and h. YOU MUST SHOW ALL WORK!!!
5. Write the genotypes of the parents in the space provided under Offspring #1.
6. Take the appropriate Gummy bear parents and place them next to their offspring (once you assign two parents to a
set of offspring, they cannot be assigned to another set).
7. Record the phenotypes of the parents in the space provided under Offspring #1.
8. Record the mode of inheritance in the space provided under Offspring #1 (i.e. complete, incomplete or codominance).
9. Repeat this procedure for the other five sets of offspring.
Name: ____________________________________________ Period: __________ Date: _____________
PreLab Questions:
1.
Based upon what you have read so far, fill in the table below with the phenotype or genotype of the purebred
Gummy bears from the original population.
Phenotype
HR H R
Breeding pair #1
Breeding pair #2
Green
h’ h’
Breeding pair #3
Breeding pair #4
Genotype
Clear
2.
If two purebred green Gummy bears mate, is it possible for them to produce an offspring that is not green?
Explain your answer (you may support your answer by drawing a Punnett square).
3.
What is the genotype is of a heterozygous green gummy bear? ____________
4.
Can you infer what the genotype is for an orange gummy bear? ______________. You will determine if you are
correct when you start completing some of the crosses below.
Offspring #1
Phenotype(s) of the offspring: ___________________________
Parent Genotypes: ________________ X ________________
Parent Phenotypes: _______________ X _______________
Mode of inheritance: ______________________________________
Offspring #2
Phenotype(s) of the offspring: ___________________________
Parent Genotypes: ________________ X ________________
Parent Phenotypes: _______________ X _______________
Mode of inheritance: ______________________________________
Offspring #3
Phenotype(s) of the offspring: ___________________________
Parent Genotypes: ________________ X ________________
Parent Phenotypes: _______________ X _______________
Mode of inheritance: ______________________________________
Name: ____________________________________________ Period: __________ Date: _____________
Offspring #4
Phenotype(s) of the offspring: ___________________________
Parent Genotypes: ________________ X ________________
Parent Phenotypes: _______________ X _______________
Mode of inheritance: ______________________________________
Offspring #5
Phenotype(s) of the offspring: ___________________________
Parent Genotypes: ________________ X ________________
Parent Phenotypes: _______________ X _______________
Mode of inheritance: ______________________________________
Offspring #6
Phenotype(s) of the offspring: ___________________________
Parent Genotypes: ________________ X ________________
Parent Phenotypes: _______________ X _______________
Mode of inheritance: ______________________________________
Concluding Questions:
1. In Gummy bears, fur color is controlled by a single gene with many alleles. How many different alleles determine
fur color?
2. What is the difference between a heterozygote for each type of dominance? In other words, how does the
heterozygote appear depending on each situation?
a. complete dominance __________________________________________________________
b. codominance ________________________________________________________________
c.
incomplete dominance_________________________________________________________
3. How can two orange bears produce a yellow bear, but two yellow bears cannot produce an orange bear? Explain
both situations completely using vocab for full credit.