Download Dragon Genetics - UCI Biology Education Research Program

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Professor Program
Discussion Leader Activity: Dragon Genetics
Author/Creator: Kara Neely, 4th year Neurobiology and Behavior
Created for: Bio93 2010
Activity Type : Small group activity
Time Needed in Discussion: 50 minutes
Learning goals: By the end of this activity, students will be able to:
 Determine genotype and consequential phenotype of an organisms
 Identify the difference between Mendelian and non-Mendelian inheritance
 Actively demonstrate to themselves the Laws of Mendelian inheritance
Abstract
Pre-class prep
Teacher passes out materials/explains activities
Students determine genotype/phenotype of baby
Teacher goes over thought questions
45 min
10 min
30 min
10 min
Supplies
 Popsicle sticks or cardboard squares
 Colored markers
 Worksheets with the code for genotypes and phenotypes
Pre-class prep
 Create dragon genome bags. Each bag will contain several sticks or squares. Each square
represents a gene with two alleles for the diploid dragon: one side has one allele, the other
side has the other allele. When students drop all their squares on the table, one allele for
each gene will land face-up. This will represent the gamete produced by the student. See
photograph in next section.
 For each square, label each side with a parental allele (See code at the end of this sheet).
Make sure to label each type of chromosome with a separate color. Make some squares
homozygous and some heterozygous.
 The ear-wiggling trait (Ee) is sex-linked. Make several squares that say “Y” on one side
instead of E or e. When you make your bags, try to make a female bag and a male bag,
and then rubber-band these together.
 Also, make sure to make the recessive allele “n” for fangs more frequent in the population.
© 2010 by the HHMI-UCIrvine Professor Program. For non-commercial, educational use only.
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Professor Program
In Class
1. (10 min) Explain the task to students. The discussion leader should explain that everyone
should pair up into groups of two, and each pair will be making a dragon baby together! Pass
out bag pairs that each contain a single diploid set of the necessary genes. Instruct them that
everyone should have one square for each trait.
2. (30 min) Students will create a dragon baby by each parent dropping their squares onto their
desk with one allele for each gene facing up.
Student 1
Student 2
One student’s dragon gamete is on the left, the other student’s gamete
is on the right. Together, the squares make the dragon “baby.” For
instance, this dragon baby has the genotype for the trait of fire spark of
Mm (pink letters).
Students will figure out the genotype and phenotype of their baby. Walk around and watch
them to make sure they are doing the task correctly and see if they have any questions. After
they are done figuring out the phenotype, make sure they answer the questions on the
worksheet.
3. Have students repack their dragon genome bags with the right genes for the next class. It
doesn’t matter that the bags are the same as before, but just that you end up with complete male
and female dragon bags again. Rubber band the bags together, or have students make a male
bag pile and female bag pile on the front table if you want to mix things up for your next
discussion.
Some students will finish quickly. Have a set of advanced questions for them, such as:
 Draw their diagram to demonstrate epistasis on the board.
 Join with a neighboring group and have your two babies mate. Draw a pedigree for a
recessive trait that includes the four grandparent-dragons, two parent-dragons, and the
baby dragon.
 If a group likes more kinesthetic learning, they can draw their dragon baby
4. (10 min) Go over the answers to the questions with the class.
© 2010 by the HHMI-UCIrvine Professor Program. For non-commercial, educational use only.
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Professor Program
Comments
The students tend to take a little time getting started on the task. Make sure to walk around
right when they get started to herd them along.
Below is a sample worksheet. It has a column for the parents genotypes (what is on both sides
of the square) and the contribution to the baby (what you gave as your “egg” and “sperm”).
This confused a lot of the students so just make sure to explain it.
The idea for this activity came from http://serendip.brynmawr.edu/sci_edu/waldron/
Several modifications were made to Kara’s version by HHMI to make it more general.
Sample Worksheet
DRAGON GENOME
Trait
Alleles
Dominance
Presence of chin spike
A, a
Presence is dominant to absence
Spot color
R, r
Fire spark
M, m
Firebreathing
G, g
Presence of fang
N, n
Presence of fang is dominant to lack of fang
Scale color
X1, X2, X3
X1 (blue) and X2 (red) are dominant over X3 (white)
and co-dominant with each other
Tail length
L, l
Long tail is incompletely dominant to short tail
Diet choice
W, w
Ear wiggling
E, e
Co-dominance, RR produces red spots, rr produces
yellow spots.
Ability to make spark is dominant to lack of ability.
The gene for fire spark is epistatic to the gene for fire
breathing
Ability to make gas for fire-breathing is dominant to
lack of ability
Simple dominance, liking to eat princesses is
dominant to vegetarianism
Ear wiggling is dominant, trait is on the X sex
chromosome (dragons have XX=female, XY=male)
© 2010 by the HHMI-UCIrvine Professor Program. For non-commercial, educational use only.
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Professor Program
Our Baby !
GENOTYPES
MOM DAD
Alleles in
Egg Sperm
TRAIT---Phenotype of Baby
Spike
Spot
Spark
Breath
Fang
Scale
Tail
Diet
Ears
Sample Questions:
1. How does dropping the squares on the table and transcribing the letters on the sides facing
up follow Mendel’s Law of Segregation? [First state the law.]
2. Why do the chin spike and spot color traits not demonstrate Mendel’s Law of Independent
Assortment? [First state the law.]
3. The gene for fangs is recessive, yet most of the dragons have fangs. How can this happen?
4. What is the sex of your baby? ______________________
5. Explain the difference between a dragon having a medium-length tail and a dragon having
both red and yellow spots.
6. Explain how there are three alleles for scale color but your dragons each have only two
each.
7. Explain epistasis in the context of your baby, using a diagram of how dragon fire is
generated (be creative, and show where the gene products would act).
© 2010 by the HHMI-UCIrvine Professor Program. For non-commercial, educational use only.