Name: Answer Key
Discussion Section (circle one): 1, 2, or 3pm
Your mate:
BioSci 93 Discussion Week 9 Activity:
Dragon Baby Genetics
Choose your mate!
Congratulations you two! After saving money for nearly a lifetime you finally have enough to
adopt and raise a dragon baby! Each pair will receive a small bag containing the parental
alleles that will determine the traits in your baby dragon. Take a chance and let each parent
drop their squares (alleles) onto their desk to identify what kind of dragon baby you will have!
Dragon Genome
Trait
Ear Wiggling
Alleles
E, e
Diet choice
D, d
Fire spark
M, m
Fire breathing
G, g
Presence of fang
Scale color
N, n
R, r
Dominance
Ear wiggling is dominant, trait is on the X sex chromosome
(dragons have XX = female, XY = male)
Simple dominance, liking to eat princesses is dominant to
vegetarianism
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
Presence of fang, n, is recessive to lack of fang, N
R is dominant and produces blue scales, whereas rr produces
green
Your awesome new dragon!
Example:
Ears
Diet
Spark
Breath
Fang
Scale
Genotypes
Mom
Dad
E e
X X
X EY
dd
Dd
MM
Mm
Gg
gg
Nn
nn
Rr
Rr
Egg
Xe
d
M
G
n
R
Alleles in…
Sperm
XE
D
M
g
n
r
1) What is the name of your adopted dragon baby?
Cherie
2) Cool. What is the sex of your baby?
Female
1 of 2 Trait (Phenotype in baby)
XEXe – Can wiggle ears
Dd – Likes to eat princesses
MM – Can make sparks
Gg – Can make gas
nn – Fangs
Rr – Blue Scales
3) The gene for fangs is recessive, yet most of the dragons have fangs. How is this possible?
Allele Frequency. There are more recessive alleles within the population compared to the
dominant allele. REMEMBER: An allele being dominant just means the phenotype of the allele
is prevalent and is shown in comparison to the recessive allele. Although it may be the dominant
allele, this has no bearing over how frequent this allele will show up within the population!
4) Your friend was jealous and so he went out to island of Berk and met a dragon couple that had
an egg up for adoption. Strangely, your friend wanted to know if the new dragon baby would be
able to wiggle his/her ears. If the mom is unable to wiggle her ears but the father is able to, what
are the chances that the baby will be able to ear wiggle? What if it is a boy? What if it is a girl?
Mom’s Genotype - XeXe
Dad’s Genotype - XEY
Possible Progeny:
(Dad) XE
(Dad) Y
(Mom) Xe
XE Xe
(Female)
X eY
(Male)
(Mom) Xe
XE Xe
(Female)
X eY
(Male)
After drawing out the Punnett square, we can see that there is 50% chance that the baby will be
able to wiggle their ears. If the baby is a female, there is a 100% (has XE) chance she will be able
to wiggle her ears. However, if the baby is a male, then there is no possibility (has Xe) of the
baby dragon to wiggle his ears.
5) Explain epistatis 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).
The ability to make a spark is a pre-requisite for fire breathing. Even if you are able to produce
the gas required for fire breathing, you wont be able to breathe fire unless you can produce a
spark. Because of this, producing sparks is epistatic to fire-breathing.
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