Use these words to brainstorm:• Heterozygous• Homozygous• Allele• Gene• Chromosome• DNA

• Punnett Square• Nucleotide• Genotype• Phenotype• Phenotypic ratio• Genotypic ratio

Punnett Square Prep

Say these aloud as fast as you can!

Round 1: Dominant or Recessive

RR

Rr

hh

Tt

R

t

a

Aa

G

g

Heterozygous or Homozygous?

hh

Tt

RR

tt

Aa

AA

Gg

gg

Get out your boards

Write the genotypes for the following:

T=Tall t= short

Tall:___________________

Short:__________________

Write the genotypes for the following:

R=Red eyed flies r= black eyed flies

Round:___________________

Box:__________________

Write the genotypes for the following:

B=Brunette b= blonde

Blonde:___________________

Brunette:__________________

Make the Punnett Square and be prepared to answer the questions that follow:

G= green spots g= white spots

Homozygous recessive parent 1Homozygous dominant parent 2

Make the Punnett Square and be prepared to answer the questions that follow:

Freckles are recessive. No freckles are dominant.

Mom= heterozygous Dad=homozygous recessive

Possible outcomes for kids?

Now answer these questions about your Punnett Square• What is the percent chance of each

phenotype?• What is the phenotypic ratio?• What is the genotypic ratio?

Make the Punnett Square and be prepared to answer the questions that follow:

D= spotted fur d= no spots

Heterozygous parent 1Heterozygous parent 2

Now answer these questions about your Punnett Square• What is the percent chance of each

phenotype?• What is the phenotypic ratio?• What is the genotypic ratio?

Make the Punnett Square and be prepared to answer the questions that follow:

N= spiny stem n= smooth stem

Heterozygous parent 1Homozygous recessive parent 2

Now answer these questions about your Punnett Square• What is the percent chance of each

phenotype?• What is the phenotypic ratio?• What is the genotypic ratio?

Make the Punnett Square and be prepared to answer the questions that follow:

B=Brown eyes b=Blue Eyes

(Bob)Heterozygous parent 1(Susie) Heterozygous parent 2

Now answer these questions about your Punnett Square• What is the percent chance of each

phenotype? genotype?• What is the phenotypic ratio?• What is the genotypic ratio?

Answer this and prove with your own punnett square

If a woman is homozygous normal and her husband is heterozygous for a genetically

inherited recessive disease and they decide to become parents, what is the probability that they will have a healthy

child?

Solve this problemBecky and Allen are having a baby. Their bouncing baby boy arrives with blue eyes, but Becky and Allen both have brown eyes. How can you prove to them that this is really their child? Create a punnett square that shows it is possible.

Look at the Punnett Square to the right to answer the questions:

• Are the parents homozygous or heterozygous?• What is the

genotypic ratio?