GENETICS
REEBOB Activity
Objective:
To explore genetic variation in a species by constructing fictitious baby “Reebops.” Students will randomly
receive the genotype of a “reebop” and construct the “reebop” according to its genes.
Pre-Lab:
Terms to be defined for this lab
homologous pair
gametes
sperm
egg/ovum
zygote
haploid
diploid
meiosis
genetic variation
phenotype
genotype
Materials:
magic markers
Antenna
Pretzel sticks
Tail
Red, blue, or green sour straws
Humps on back
Green mini marshmallows connected with half
toothpicks
Yellow, orange, or pink mini marshmallows
connected with half toothpicks
Nose color
Legs (number)
Eyes
Body Segments and Head
Procedure:
Green, blue, or brown jelly beans connected with
half toothpicks
Large white marshmallows connected with
toothpicks
1. Divide into groups of 2. If there are an odd number of students, you will have to have one group of 3.
2. Each group will receive an envelope containing one set of parent chromosomes. One person from each group should
take responsibility for the chromosomes.
3. One color of chromosomes is from the mother and the other is from the father. Separate the chromosomes into two
separate piles according to their color. On your answer sheet, designate which chromosomes belong to which parent
before you start. (ie. Mother’s Chromosomes = purple, Father’s Chromosomes = red)
4. Look at the 14 chromosomes in the Mother pile. Match up the homologous pairs. A homologous pair will be the same
length. You should have 7 pairs when you are done sorting them out. Lay the mother’s homologous pairs in a row,
face down to the left of your lab table.
5. Repeat step 4 for the father’s chromosomes and place them to the right of your lab table.
6. Look at the largest homologous pair of the mother. Choose ONE of the two. Place the rejected one back in the
envelope.
7. Look at the largest homologous pair of the father. Choose ONE of the two. Place the rejected one back in the
envelope.
8. Repeat steps 6-7 for the other 6 homologous pairs of the mother and father.
9. You should have 7 chromosomes from the mother and 7 from the father. Match up the homologous pairs- in
each pair one should be from the mother and one should be from the father.
10. On your answer sheet, write down the 7 gene pairs (genotypes) that were selected in Table 1.
11. Next write down the phenotypes (physical traits or features) that your baby reebop will have. Use the genotypes and
phenotypes below in the “Reebop Genetic Decoder”.
12. Based on your baby reebop’s traits, make a ‘shopping list’ of the parts you’ll need to build your baby by filling in
Table 1 on your answer sheet. All baby reebops have a head so the minimum number of marshmallows you need is
two ( one body segment & a head). Also, be sure you’ve accounted for the total number of toothpicks you will needthey will be used to connect body parts together AND used for the legs. Once you have checked your list
thoroughly, place all of the chromosomes back in the envelope.
13. One person from each group should bring the envelope with ALL of the chromosomes and the shopping list to the
Parts Manager (teacher!) to collect your reebop parts. (DO NOT EAT ANY PART OF YOUR CHILD OR POINTS WILL BE
DEDUCTED FROM YOUR LAB).
14. Using the list you made and the parts you’ve collected, construct your baby reebop. Once you’ve finished, select a
name for your baby and write it on a sheet of paper, along with the names of the members in your group. Take your
baby reebop and its name tag to your teacher to turn in for a grade.
Reebop Genetic Decoder:
AA= 1 antenna
Aa = 2 antenna
aa = no antenna
MM = 1 green back hump
Mm = 2 green back humps
mm = 3 green back humps
QQ = yellow nose
Qq = orange nose
qq = pink nose
EE = 2 green eyes
Ee = 2 blue eyes
ee = 2 brown eyes
LL or Ll = 2 legs per body segment
ll = 3 legs per body segment
TT = red tail
Tt = blue tail
tt = green tail
DD or Dd = 1 body segment
dd = 2 body segments
Name(s)___________________________________________________________ Period ________________
Genotype
Phenotype
Materials Needed
Qty
ntity
1
2
3
4
5
6
7
Total # of toothpicks needed: ________________________________________
1.
Which traits were heterozygous? What was the phenotype?
2. Which traits were homozygous dominant?
3. Which traits were homozygous recessive? What was the phenotype?
4. Why weren’t all of the marshmallow creatures in class identical? Explain in terms of the meiotic process.
5. If two babies both had red tails, would their genotypes for that trait have to be identical? Show the
possible genotypes.
6. If two babies both had an orange nose and one green hump, would their genotype have to be identical for
these traits? Show the possible genotypes.
7. If the chromosomes that determine gender had been a part of this activity, which allele (X or Y) would
have determined the gender of the baby?
8. Did you have any genes which were an example of incomplete dominance? Explain.
9. Which trait involves multiple alleles, and what are the alleles involved?
10. Which trait, if any, was an example of co-dominance? How does this differ from incomplete dominance?
11. What genetic pattern did the gene for nose color illustrate? Explain.
12. Draw a monohybrid cross Punnet square for the trait of tail type (for this example, mom is heterozygous
and dad is homozygous dominant) and predict the probability of getting a baby which displays your baby’s
phenotype for this trait.
A a
M m
T
E e
L
Q q
t
l
D d