Download dragon genetics lab

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DRAGON GENETICS LAB
INTRODUCTION
In this activity, you and a partner will work together to produce a baby dragon. You will simulate meiosis and
fertilization. To begin, we will review meiosis and fertilization for dragons that have only one chromosome
with a single gene.
This gene codes for the enzyme that makes the pigment that gives dragon skin its color.
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The dominant allele, A, codes for a normal enzyme that results in normal skin color.
The recessive allele, a, codes for a defective enzyme that cannot make skin pigment, so an aa dragon is an
albino with completely white skin.
★ Suppose that each dragon parent has the pair of homologous chromosomes shown.
Father
Mother
_A
_A
_a
_a
Draw the chromosomes of the two types of eggs and the two types of sperm produced by meiosis. Then, draw
the chromosomes of the zygotes that are produced when the different types of sperm fertilize the different
types of eggs. Next, use an * to indicate any zygote or zygotes that will develop into albino baby dragons.
In this activity you will work with a partner to carry out a simulation of meiosis and fertilization and produce a
baby dragon. Each student will be a surrogate dragon parent who has the genes indicated on a set of three
Popsicle sticks. Each Popsicle stick represents one chromosome, and the two of the same color represent
homologous chromosomes. This table explains how the simulation mimics the biological processes of meiosis
and fertilization.
The homologous chromosomes will be separated according to Mendel’s law of Independent Assortment. The genetic
codes that are passed on to the baby will be recorded on the following pages. The surrogate parents must then decode
the genes inherited by their bundle of joy to determine the phenotype traits of their baby. Using the pictures provided,
they will cut out these traits and paste them together to have a picture of their baby.
Biological Process
Simulation
The parents' diploid cells have pairs of homologous
chromosomes. Meiosis separates each pair of homologous
chromosomes, so each gamete receives only one from each
pair of chromosomes. Thus, the parents' diploid cells have
two copies of each gene, but each haploid gamete has only
one copy of each gene.
Each dragon parent puts his or her Popsicle
sticks on the table or desk, and randomly
separates the Popsicle sticks into the separate
gametes. The alleles from this chromosome are
recorded in the Egg or Sperm column in the
charts on page 4.
When a haploid sperm fertilizes a haploid egg, this produces The dragon parents record the phenotypic traits
a diploid zygote with one copy of each gene from the
of their baby in the Baby's Traits column in the
mother and one copy from the father. These genes
charts on page 4.
determine the phenotypic traits of the baby dragon that
develops from this zygote.
Mendel’s Law of Independent Assortment
The principles that govern heredity were discovered by a monk named Gregor Mendel in the 1860's. One of these
principles, now called Mendel's law of independent assortment, states that allele pairs separate independently during
the formation of gametes. This means that traits are transmitted to offspring independently of one another.
Mendel’s Law of Segregatoin
Mendel's law of segregation states that allele pairs separate or segregate during gamete formation, and randomly unite
at fertilization. There are four main concepts involved in this idea. They are:
1. There are alternative forms for genes. This means that a gene can exist in more than one form.
2. For each characteristic or trait organisms inherit two alternative forms of that gene, one from each parent. These
alternative forms of a gene are called alleles.
3. When gametes (sex cells) are produced, allele pairs separate or segregate leaving them with a single allele for each
trait. This means that sex cells contain only half the compliment of genes. When gametes join during fertilization the
resulting offspring contain two sets of alleles, one allele from each parent.
4. When the two alleles of a pair are different, one is dominant and the other is recessive. This means that one trait is
expressed or shown, while the other is hidden.
From Mendel's law of segregation we see that the alleles for a trait separate when gametes are formed (through a type
of cell division called meiosis). These allele pairs are then randomly united at fertilization. If a pair of alleles for a trait are
the same they are called homozygous. If they are different they are called heterozygous.
PROCEDURE
1. Choose a partner carefully. You and your spouse will share the grade for this lab. Your instructor does not care
which partner worked the hardest. This is a no divorce classroom. The lab must be completed on time.
2. Each partner must pick up ten Popsicle sticks -- two of each color of autosome (green, purple, orange, and
yellow) and two sex chromosome stick (blue or pink). Each stick represents a chromosome, and the pair
together represents homologous chromosomes.
3. For each color autosome and then for the sex chromosomes follow steps:
a. Each parent will hide his or her stick behind their back.
b. The other person will randomly choose one chromosome to put down on the table.
c. This will show the alleles passed onto the baby.
4. The alleles from each pair of homologous chromosomes will be recorded in the data chart.
5. The decoding chart indicates the phenotypic effect of each gene. The trait produced by each pair of alleles
should be recorded in the data chart. Remember that a CAPITAL letter is dominant over a small letter
[recessive] unless the decoding chart indicates those traits are codominant, sex-influenced, or sex-limited.
6. Students will use the key to draw their dragon. They may trace the features, but your teacher much prefers if
you use your skills and create a drawing.
7. The baby’s colors will be added to the picture.
DRAGON GENOME
DECODING OF THE GENES
Chromosome
Green Autosome
Dominant genes
A. no chin spike
B. Nose spike
C three head flaps
D. no visible ear hole
E. (see below)
Recessive genes
a. chin spike
b. no nose spike
c. four head flaps
d. visible ear hole
Purple Autosome
F. long neck
G. no back hump
H. no back spikes
I. long tail
J. flat feet
f. short neck
g. back hump
h. back spikes
i. short tail
j. arched feet
Orange Autosome
K. red eyes
L. spots on neck
M. (see below)
N. no fang
O. spots on back
k. yellow eyes
l. no spots on neck
P. no spots on thigh
Q. green body
R. small comb on head (see below)
S. See below
T. See below
U. regular thigh
V. four toes
W. no chest plate
p. spots on thigh
q. purple body
r. large comb on head
X Chromosome only
X. no tail spike
Z. long arms
+ non-fire breather
x. tail spike
z. short arms
- fire breather
Y chromosome only
Y male
Yellow Autosomes
Sex Chromosomes
n. fang
o. no spots on back
u. pointed thigh
v. three toes
w. chest plate
Co-Dominant traits (both show up)
E. eye pointed at each end
S. Red spots
e. round eye
s. yellow spots
Sex Influenced traits
M. wings
T. no elbow spike
m. no wings (dominant in presence of male hormone)
t. elbow spike (dominant in presence of male hormone)
Sex Limited traits
R or r Only males have the comb on the head
Ee. Eye round at front
Ss. Orange spots
OUR BABY DRAGON!
Name:
Your Partner:
your chromosome gender and number:
your partner’s chromosome gender and number:
*Use punnett squares for probability
Green Autosomes
GENOTYPES
MOM DAD
Alleles in
Egg
Sperm
Show probability for chin spike
Purple Autosomes
GENOTYPES
MOM DAD
Alleles in
Egg
Sperm
Show probability for neck length
Orange Autosomes
GENOTYPES
MOM DAD
Alleles in
Egg
Sperm
Show probability for eye color
TRAIT—Phenotype of Baby
Show probability for number of flaps
TRAIT—Phenotype of Baby
Show probability for tail length
TRAIT—Phenotype of Baby
Show probability for neck spots
Yellow Autosomes
GENOTYPES
MOM DAD
Alleles in
Egg
Sperm
TRAIT—Phenotype of Baby
Show probability for body color
Sex Chrosomes
GENOTYPES
MOM DAD
Alleles in
Egg
Sperm
Show probability for spots on thigh
TRAIT—Phenotype of Baby
Questions
Answer on binder paper and staple to data.
1. How does dropping the stick on the table and transcribing the letters on the sides facing up follow Mendel’s
Law of Segregation? [First state the law.]
2. Explain how dropping the green, orange, and red sticks illustrates 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. What traits are sex-linked? [First define “sex-linked”.]
6. Identify any gene deletions or inversions in the chromosomes you have.
7a. What traits are more likely to be found in males? [Consider sex-linked, sex-influenced and sex-limited
traits.]
7b. How might these be an advantage to this sex? [Be creative in your answers.]
8. Suppose that Mom and Dad had a second baby. Would the second baby necessarily have this same traits as the first?
Why or why not?
9. For this couple, will all of their sons have horns? Explain why or why not.
10. Which sex will be more likely to have horns. How might horns be an advantage for this sex?
Phenotypic Trait Can two individuals with this phenotype have different genotypes?If yes, give an example
Has wings
Has red eyes
Has a short tai