Reebop Genetics
Purpose: To demonstrate the process of how genes
are passed from parents to offspring, the concept of
dominant and recessive traits, and the difference
between genotype and phenotype.
Background:
Heredity is the passing of physical characteristics, or traits, from parents to offspring.
Traits, such as stem height or hair color, vary between individuals and are determined by genetic
material inherited from each parent. Scientists use the term "gene" for the unit of genetic material
that controls a specific trait. Alleles are the different forms of a gene. An organism inherits one
allele from each parent, so every gene is controlled by a combination of two alleles. A dominant
allele is one whose trait always shows up in the organism when that allele is present. A recessive
allele is hidden or masked whenever the dominant allele is present. The allele combination or
genetic makeup of an organism is called its genotype, while its physical appearance is called its
phenotype. Genotypes are represented by 2 letters, one for each allele (i.e. AA, Aa, or aa). The
dominant allele is usually a capital letter (i.e. A) and the recessive allele is usually a lower-case
letter (i.e. a). A genotype may be homozygous for a trait if an organism has two identical alleles,
or heterozygous for a trait if an organism has two different alleles.
Materials: Styrofoam balls, toothpicks, pipe cleaner, thumb tacks, paper clips, push
pins, paper chromosomes
Procedures:
You will work with a partner for this activity. One of you will be the MOM Reebop and
one of you will be the DAD Reebop.
1. Take your chromosomes out of the envelope (Mom = pink, Dad = blue), and
match like letters together. Keep Mom and Dad chromosomes separate.
2. These chromosomes are the parent genotypes. Record these genotypes in Table 1.
3. Arrange the chromosomes on the table so that they are face down in height order
(biggest to smallest).
4. Take turns picking one allele from each set of chromosomes and set them aside.
These will be the alleles that your Baby Reebop will inherit.
***Double check that you have 16 alleles total: 8 pink and 8 blue!
5. Match up the alleles for each letter (1 pink with 1 blue). These are the genotypes
that your Baby Reebop will inherit. Record these genotypes in Table 2.
6. Determine your Baby’s phenotypes from the genotypes that you recorded.
***You must get approval before building your Baby Reebop!
7. Using the phenotypes you determined, build your Baby Reebop with the
appropriate materials. Name your Baby Reebop and record who the parents are.
1
Data:
TABLE 1: Parent Genotypes
Mom’s
Genotype
Trait
Allele Passed
to Baby
Dad’s
Genotype
Allele Passed
to Baby
Body (B/b)
Tail (T/t)
Legs (D/d)
Eyes (E/e)
Antenna (A/a)
Nose (Q/q)
Wings (M/m)
Sex (XX/XY)
TABLE 2: Baby Genotypes and Phenotypes
Trait
Baby’s Genotype
Baby’s Phenotype
Body (B/b)
Tail (T/t)
Legs (D/d)
Eyes (E/e)
Antenna (A/a)
Nose (Q/q)
Wings (M/m)
Sex (XX/XY)
Analysis Question:
1. In humans, the allele for free earlobes (F) is dominant over the allele for attached
ear lobes (f).
a. What possible genotypes could a person with the free earlobe phenotype have?
_____________________________________________________________
b. What possible genotypes could a person with attached earlobes have?
_____________________________________________________________
2
TABLE 3: Rebops - Genotypes to Phenotypes*
Trait
Dominant
Recessive
Material
Body (B/b)
2 segments
(BB or Bb)
1 segment (bb)
Playdough
Tail (T/t)
Curly tail
(TT or Tt)
Straight tail (tt)
Pipe cleaner
Legs (D/d)
4 legs per segment
(DD or Dd)
3 legs per segment
(dd)
Push pins
Eyes (E/e)
2 Black
(EE or Ee)
2 White or 2 Red
(ee)
Map/round pins
Antenna (A/a)
1 (AA or Aa)
2 (aa)
Paper clips
Nose (Q/q)
Orange
(QQ or Qq)
Blue (qq)
Thumb tacks
Wings (M/m)
Wings
(MM or Mm)
No wings (mm)
Clip
Sex (XX/XY)
Girl (XX)
Boy (XY)
--
*All traits are completely dominant
Standards Addressed:
Genetics
2.b. Students know that sexual reproduction produces offspring that inherit half their genes
from each parent.
2.d. Students know plant and animal cells contain many thousands of different genes and
typically have two copies of every gene. The two copies (or alleles) of the gene may
or may not be identical, and one may be dominant in determining the phenotype
while the other is recessive.
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