MARSHMALLOW MEIOSIS LAB : Rebops
Original Author: Unknown
Presented by: Tracy M Harper, Western Technical College
Introduction:
Rebops are marshmallow ‘animals’ that have eight characteristics that are
determined by their ‘genetic makeup’. Each trait is represented by both a
dominant and recessive trait, which depending on how the genes are inherited,
will determine the phenotype of the offspring. Rebop offspring traits are made
based the genes they inherit from the parents.
Learner Objectives:
1. Apply the principles of meiosis and genetic transfer of traits.
2. Determine traits of an offspring based on genetic information from
chromosomes by simulating a model of meiosis.
3. Relate the genotype to the phenotypic expression of a trait.
4. Determine the mathematical probability of the genotype and phenotype
of offspring produced from a Rebop sire and dam.
Assessment Strategies:
Teacher observation
Lab activity analysis questions
Time Allocation
This lesson plan requires 1 hour of in class lab time, and an additional 1 hour of
individual practice time to complete the assignment.
LAB PREPRATATION
MARSHMALLOW MEIOSIS LAB : Rebops!
Materials and Supplies:
Large Marshmallows
Mini Marshmallows, colored
Multi colored push pins
Blue Pipe Cleaners
Toothpicks
Thumbtacks (or different colored toothpicks for the antenna)
Preparation:
1. Create the eight gene pairs listed including the sex chromosomes.
All eight gene pairs should be cut at different lengths.
Each chromosome should have its partner cut at the same length.
Each parent will have a heterozygous pair of genes, the sire’s genes are blue,
and the dam’s genes are red.
X
L
T
M
D
E
Q
A
X
Y
L
l
T
t
M
m
D
d
E
e
Q
q
a
TM HARPER
MANUSCRIPT, Page 2
A
a
q
e
d
m
t
l
Y
Use the following traits:
Physical trait
Genes
Supply
Antenna
Aa
Thumbtacks
Nose
Qq
Colored Mini Marshmallow: pink, orange
or yellow
Eyes
Ee
Thumbtacks or push pins
Body Segments
Bb
Large Marshmallows
Humps
Mm
Green Mini Marshmallows
Tail
Tt
Pipe Cleaner
Legs
Ll
Toothpicks
Sex
XX or XY
2. Make up at least one Rebop parent for example.
MINI
MARSHMALLOWS
PIPE
CLEANER
Thumb Tacks
or Push Pins
MINI
MARSHMALLOW
MARSHMALLOW
TOOTH
PICK
3. Students should work in pairs for this exercise, with each pair building their
own Rebop. Each student pair should start with a Sire and Dam Rebop set of
chromosomes. Students will select one chromosome from the sire (blue) and
one from the dam (red) for each gene pair. This mimics fertilization, where
one trait is inherited from each parent, and will result will be a ‘genetic code’
for their Rebop.
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MANUSCRIPT, Page 3
4. Every student will likely end up with a different genetic code for their Rebop.
However, in the event that there two identical Rebop babies…they have
twins!
Part II
Determining Heritability
1. Have students find a suitable mate for their Rebop, allowing students to
use a Rebop ‘stud’ more than once.
2. Using the Pearson Square, have students determine the probability of the
expression of genetic and physical traits based on their cross.
TM HARPER
MANUSCRIPT, Page 4
STUDENT LABORATORY
MARSHMALLOW MEIOSIS
Part I: The Making of a baby Rebop
1. Select one chromosome from each parent for each trait . You should
have two gene’s ( one red, one blue) for each trait.
2. Using the supplies given and the Decoder Key, construct your own Rebop.
3. Record the genotype and phenotype of your Rebop.
GENOTYPE
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PHENOTYPE
Rebop Decoder Key
AA = one antenna
MM = 3 green humps
Aa = two antenna
Mm = 3 green humps
aa = zero antenna
mm = 2 green humps
QQ = red nose
TT = curly tail
Qq = orange nose
Tt = Curly tail
qq = yellow nose
tt = straight tail
EE = 3 eyes
LL = Blue legs
Ee = 3 eyes
Ll = Blue legs
ee = 2 eyes
ll = red legs
DD = 3 body segments
XX = female
Dd = 3 body segments
XY = male
dd = 2 body segments
TM HARPER
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STUDENT LABORATORY
MARSHMALLOW MEIOSIS: Rebops!
Part II: Determining Heritability
1. Determine the sex of your Rebop by selecting a sex chromosome from
each parent Rebop.
2. Select a suitable mate for your Rebop, you may use a sire more than
once, but not the dam.
3. Using a Pearson Square for each trait, determine the probability of both
the genotype and phenotype of the offspring.
Antenna
Nose
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MANUSCRIPT, Page 7
Eyes
Body Segements
Humps
Tails
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Legs
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