SBI 3U Genetic Continuity
Name: _______________________ Partner’s name: __________________________
Breeding Reebops
Objective: To explore genetic variation in a species by constructing baby "Reebops" from two
heterozygous parents. Once you have found your partner, and have collected all the materials needed,
you may begin to breed your Reebops.
Materials:
-Complete set of mother chromosomes
c) tooth picks
-Complete set of father chromosomes
d) nails
-Materials need for construction of Reebop
(number of each material dependent on
genotype):
e) pipe cleaners
f) paper clip pieces
a) marshmallows (large and small)
g) markers (purple, red, orange, yellow)
b) pushpins (coloured and colourless)
h) Reebop decoder key
Instructions:
1. Find your partner using the images on your envelopes. One partner will take the mother's
chromosomes, and the other will take the father's chromosomes.
2. Remove the 16 chromosomes from the envelope. Match up the homologous pairs. A homologous
pair will be the same length. You should have 8 pairs when you are done sorting them out. Record
your parents' genotype in Table 2.
3. Lay the homologous pairs in a row, face down so the letters are not showing.
4. Look at the longest homologous pair of chromosomes. Choose ONE of the two. Place the rejected
one back in the envelope. Do the same for the other chromosome pairs.
5. Place the chosen mother chromosomes along with the chosen father chromosomes in a separate
baby pile. This new set will be your Reebop baby's chromosomes.
6. Each Reebop baby should have 16 chromosomes. Match up the homologous pairs. One
chromosome in each pair should be from the mother and one should be from the father. Sort these
chromosomes according to length to create a karyotype.
7. Predict what your baby's genotype might be and record your predictions in Table 2 (yes it is ok to
guess!).
8. Discover your baby's genotype by turning over the chromosomes and record it in Table 2.
9. Discover what your baby looks like using the decoder key in Table 1. Record the phenotype in Table
2.
10. Construct your baby according to your chromosomes, using the materials provided. (DO NOT EAT
ANY PART OF YOUR CHILD OR POINTS WILL BE DEDUCTED FROM YOUR LAB).
11. Once your baby is constructed, give it a name. On a piece of paper, write your Reebop baby's name,
along with the names of the members in your group. As proud parents you will place your completed
Reebop baby in the designated nursery.
Table 1. Reebop decoder key. Use the following key to determine the genotype
and phenotype of your Reebop parents and baby.
Genotype
Phenotype
Materials used to represent the
phenotype
TT
Tt
tt
curly tail
curly tail
straight tail
pipe cleaners
EE
Ee
ee
2 eyes
2 eyes
3 eyes
purple marker
DD
Dd
dd
two body segments
two body segments
three body segments
2 marshmallows
2 marshmallows
3 marshmallows
MM
Mm
mm
1 hump
2 humps
3 humps
small marshmallows
red nose
orange nose
yellow nose
red marker
orange marker
yellow marker
LL
Ll
ll
4 coloured legs
2 coloured, 2 colourless legs
4 colourless legs
coloured push pins
coloured and colourless push pins
colourless push pins
AA
Aa
aa
1 antenna
2 antenna
no antenna
nails
XXd
XdXd
XdY
small ears
large ears
large ears
small paper clip pieces
large paper clip pieces
large paper clip pieces
QQ
Qq
qq
Results
Table 2. Genetic variation. Use this table to record your observations.
Phenotype
Tail
Eyes
Body
segment
Humps
Nose
Legs
Antenna
Ears
Parents'
genotype
Predict
your
baby's
genotype
(Guess)
What is
your
baby's
genotype?
What is
your baby's
phenotype?
How does
this
compare
to the rest
of the
class?
(examine
those in
the
nursery)
Why?
Questions
1. Define the following terms using your own words and give examples.
Term
Meaning
Chromosome
Example
Homologous
pair
Genotype
Phenotype
Haploid
Diploid
Genetic
variation
2. Did the baby inherit any traits from the parents?
3. a) When you observed the other babies in the nursery, were any two exactly alike?
b) Why do you think they were all different?
c) What makes identical twins identical?
4. Were any mutations formed? If so, how could this happen in this activity?
5. What does it mean when an organism is homozygous for a trait or heterozygous for a trait?
6. What is the purpose of meiosis?
Ticket out of class:
Based on the introduction to genetics given in this activity, what are two ideas or concepts you would
like to explore in the Genetic Continuity unit.
i.e. Why is diversity important? What would happen to the population of Reebop babies if they were
all the same?