“Monster Mash” Punnett Squares
Directions:
1. Read through the explanations of incomplete dominance, codominance, and
regulatory genes
2. Use a coin (or coin flip simulator) to determine the traits of the female monster.
Flip twice for each trait
a. Heads = allele 1
b. Tails = allele 2
3. Write down the genotype and phenotype for each trait for the female monster in
the chart below.
4. Fill in the missing genetic information in the male monster’s chart
5. Baby time! Using the genetic information of the parents, make Punnett squares
for the baby monster for each trait
6. Determine the percent chance of the baby monster having each of the possible
outcomes for each trait
7. Draw a picture of your monster(s)
Explanations:
- Incomplete dominance: one allele for a trait is not completely expressed over the
other. This will give a third phenotype that is a blend of each allele.
- Example: the alleles for flower color show incomplete dominance. So
when you cross a red flower with a yellow flower, you get an orange flower
(red + yellow = orange)
- Codominance: neither allele can dominate the other allele. This will give a third
phenotype that shows both alleles.
- Example: the alleles for flower color show codominance. So when you
cross a red flower with a white flower, you get a red and white flower
(red + white = red and white)
- Regulatory gene: a type of gene that can “silence” other genes from being
expressed. If the regulatory gene is present, then any other genes related to it
will be silenced.
- Example: a regulatory gene could exist in a cat breed that can keep the
cat from having a tail. If the regulatory gene is present, any genes related
to the tail (color, fur length, etc.) will be “silenced” and the cat will not have
a tail.
Female Monster Genotype and Phenotype
Trait Allele 1 Allele 2 Genotype Phenotype
Eyes 2 small eyes 1 large eye (e)
(E)
Eye color Red (R) White (R’)
(incomplete)
Skin color Greeen (G) Blue (B)
(codominant)
Tail shape Curly (C) Straight (c)
Tail color Purple (P) Orange (p)
Tail (regulatory Have tail (T) No tail (t)
gene)
Teeth Sharp (S) Round (s)
Feet 4 toes (F) 2 toes (F’)
(incomplete)
Horn color Purple (W) White (w)
Ear shape Pointy (Y) Round (y)
Ears No ears (N) 2 ears (n)
(regulatory)
Claws Long (L) Short (l)
Male Monster Genotype and Phenotype
Trait Genotype Phenotype
Eyes ee
Eye color (incomplete) White
Skin color (codominant) Green
Tail shape Straight
Tail color Pp
Tail (regulatory) No tail
Teeth Round
Feet (incomplete) FF’
Horn color ww
Ear shape yy
Ears (regulatory) Have 2 ears
Claws short
Punnett Squares:
Eyes:
Eye Color:
Skin color:
Tail shape:
Tail color:
Tail:
Teeth:
Feet:
Horn color:
Ear shape:
Ears:
Claws: