Name ________________________________________________________
The Secrets of Bedrock
Sex-linked Traits with Fred and Wilma
Background
Geneticists have succeeded in sequencing the genes on the sex chromosomes of
Bedrock’s most famous couple, Fred and Wilma Flintstone. Shocking discoveries
have been made - the secrets of Bedrock can now be revealed.
Part I: Flintstone Family Secret Analysis:
Use the data for Fred & Wilma’s sex chromosome in the tables below to answer questions
1-15 in the spaces provided.
Traits on the X chromosome (in the order they appear from top to bottom)
Dominant
Recessive
O – predisposed to obesity
N – Normal vision (can see red and green)
B – Normal hair growth
H – Normal blood clotting
D – Normal hearing
P – Pigmented eyes (brown, blue, or green)
E – Faulty tooth enamel
S – Sweat glands present
M – Not predisposed to migraines
1.
o – not predisposed to obesity
n – red-green colorblindness
b – baldness
h- hemophilia (blood does not clot)
d – deafness
p – red eyes (no pigment)
e – normal tooth enamel
s – sweat glands absent
m – predisposition to migraines
Use the genotype for Fred and Wilma to figure out their phenotype. Write each
phenotype in the space provided in the table.
X-Linked
Traits
Trait
Obesity
Color Vision
Hair Growth
Blood Clotting
Hearing
Eye Pigment
Tooth Enamel
Sweat Glands
Migraines
2.
Fred’s
Genotype
Fred’s
Phenotype
Wilma’s
Genotype
Wilma’s
Phenotype
XOY
XnY
XBY
XHY
XDY
XpY
XEY
XsY
XmY
Obesity
XoXo
XNXn
XbXb
XHXh
XdXd
XPXp
XeXe
XSXs
XMXM
No obesity
colourblind
Normal
Normal
Normal
Red eyes
Faulty
No sweat
Predis.
Normal/carrier
baldness
Normal/ca
deafness
Pigmented/ca
Normal
Present/ca
Not predis.
Can Wilma tell the difference between red and green Christmas lights? __Yes____ (YES or
NO). Explain.
She has heterozygous normal vision XNXn (however she is a carrier, but the dominant gene is
normal vision)
By Ms. Jenny Holt, 2012
3.
Does Wilma have faulty tooth enamel? ___No___ (YES or NO). Explain.
Normal tooth enamel because she is homozygous recessive XeXe
4.
Do you think Wilma has to get her hair cut & colored often? __No____ (YES or NO).
Explain.
No because she is homozygous recessive bald XbXb
5.
Are there traits for which Wilma is a carrier? If so, list all of them or explain why not.
Colourblindness
Hemophilia
red eyes
sweat glands
She is a carrier because her genotype contains one of the alleles that codes for the sex-linked
trait therefore she is heterozygous making her a carrier
6.
Are there traits for which Fred is a carrier? If so, list all of them or explain why not.
No because he only has one X chromosome therefore he either expresses sex-linked traits or he
doesn’t. He does not have the opportunity to express dominant gene while obtaining recessive
gene simultaneously.
7.
Is Fred lying when he tells Wilma that he thinks her hair is a gorgeous shade of red?
___Yes__ (YES or NO). Explain.
Her genotype contains two recessive alleles that expresses baldness therefore he may like her
wig colour but she would not have a hair colour to express if she is bald
8.
A dedicated pet owner, Fred walks Dino once a day, but has a hard time cooling his body down.
Explain why this is true. (hint: what feature helps people lose heat when they are exercising).
Fred has no sweat glands! His X chromosome contains the recessive allele for no sweat glands.
XsY Sweat glands are an important gland in thermoregulation
9.
Does Fred need to wear a toupee (which is a wig for a man)? __NO____ (YES or NO).
Explain.
His genotype contains the dominant allele for normal hair XBY
By Ms. Jenny Holt, 2012
Does Pebbles (their daughter) need to be treated for faulty tooth enamel? Set up a Punnett
square to show your answer. Answer YES or NO and circle the possible genotypes of
Pebbles in the Punnett Square.
Let XE represent the allele for faulty tooth enamel
Let Xe represent the allele for non-faulty tooth enamel
Let Y= male
XE
Y
10.
Xe
Xe
XEXe
XeY
XEXe
XeY
Yes in this case faulty tooth enamel
Is a dominant trait and pebbles genotype
Would contains one dominant allele
Since the female offspring have 100%
Of obtaining the dominant allele for faulty
Teeth
11.
Does Pebbles wear a wig? Set up a Punnett square to illustrate your answer. Answer YES or
NO and circle the possible genotypes of Pebbles in the Punnett Square.
Let XB represent the allele for normal hair
Let Xb represent the allele for baldness
Let Y= male
XB
Y
Xb
XBXb
XbY
Xb
XBXb
XbY
NO she does not. Her genotype is heterozygous (female offspring have 100% of inheriting a
heterozygous genotype), meaning she is a carrier for baldness however she also has the dominant
allele for normal hair, which means she will express normal hair
By Ms. Jenny Holt, 2012
12.
What percent chance does Pebbles have to be predisposed to obesity? Show work.
Let XO represent the allele for normal hair
Let Xo represent the allele for baldness
Let Y= male
XO
Xo
Xo
Y
XOXo
XoY
XOXo
XoY
0% chance, she is a carrier for predisposition for obesity however she will not express this trait as
she also possesses the dominant allele for no obesity.
13.
If Fred and Wilma had a son, what are his chances of having normal vision? Show work.
14. Let XN represent the allele for normal vision
15. Let Xn represent the allele for colourblindness
16. Let Y= male
Xn
Y
XN
XNXn
XNY
Xn
XnXn
XnY
50% chance of normal vision, 50% chance of colourblindness
17.
Does Wilma get angry when Fred screams…”WILMAAAAAAAAAA”? Explain.
No she is deaf (homozygous recessive XdXd) so she wouldn’t hear
his volume
By Ms. Jenny Holt, 2012
Family Fraud!
A young man named “Fredrick” has just arrived in Bedrock, and he claims to be the son of one of
the Flintstones!! Who fathered/mothered Fredrick? It’s up to you to solve this mystery.
Fortunately Fredrick agreed to DNA sequencing and the results are now in.
Procedures:
Use Fredrick’s X and Y chromosomes to answer the following questions.
1.
Fill in Fredrick’s genotype for each sex-linked trait in the table below.
Trait
Obesity
Color Vision
Hair Growth
Blood Clotting
Hearing
Eye Pigment
Tooth Enamel
Sweat Glands
Migraines
Fredrick’s Genotype
XoY
XnY
XbY
XHY
XDY
XpY
XeY
XsY
XmY
Fredrick’s Phenotype
No obesity
2.
Could Fred be the father of Fredrick? Provide “genetic evidence” to support your answer.
3.
Could Wilma be Fredrick’s mother? Provide “genetic evidence” to support your answer.
Concluding Questions:
4.
Which parent determines the gender of the child? Explain why.
5.
Why are males affected by recessive sex-linked diseases more often than females?
6.
If a male has a disease that is Y-linked, what percentage of his sons will inherit the disease?
7.
If a male has a disease that is Y-linked, what percentage of his daughters will inherit the disease?
What percentage will be carriers?
By Ms. Jenny Holt, 2012