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
Materials and Supplies:
Large Marshmallows
Mini Marshmallows, colored
Multi colored push pins
Blue Pipe Cleaners
Toothpicks
Thumbtacks (or colored toothpicks for 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; the dam’s genes are red.
X
L
T
M
D
E
Q
A
a
X
Y
l
L
t
T
m
M
d
D
e
E
q
Q
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.
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
TM HARPER
MANUSCRIPT, Page 2
Name: ____________________________
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
AA = one antenna
Aa = two antenna
aa = zero antenna
QQ = red nose
Qq = orange nose
qq = yellow nose
EE = 3 eyes
Ee = 3 eyes
ee = 2 eyes
DD = 3 body segments
Dd = 3 body segments
dd = 2 body segments
TM HARPER
MANUSCRIPT, Page 3
PHENOTYPE
Rebop Decoder Key
MM = 3 green humps
Mm = 3 green humps
mm = 2 green humps
TT = curly tail
Tt = Curly tail
tt = straight tail
LL = Blue legs
Ll = Blue legs
ll = red legs
XX = female
XY = male
STUDENT LABORATORY: MARSHMALLOW MEIOSIS
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 Punnet Square for each trait, determine the probability of both the genotype and
phenotype of the offspring.
Antenna
Humps
Nose
Tails
Eyes
Body Segements
TM HARPER
MANUSCRIPT, Page 4
Legs