Name:
Bikini Bottom Genetics
1. For each genotype, decide if it is heterozygous or homozygous. Use an “E” for the heterozygous genotypes and an “O” for the homozygous genotypes.
TT_O_ Bb__E_ ff__ O __ Tt__ E __ BB__ O __ Ff__ E __
2. Which of the genotypes in #1 would be considered purebred? TT, ff, BB
Which of the genotypes in #1 would be considered hybrids? Bb, Tt, Ff
3. Determine the phenotypes for each genotype using the information provided about SpongeBob.
Yellow body color is dominant to blue.
YY___yellow____ Yy___yellow____ yy____blue_____
Square shape is dominant to round.
SS__square____ Ss___square______ss____round______
4. For each phenotype, give the genotype or genotypes that are possible for Patrick
A tall head (T) is dominant to short (t).
Tall=__TT or Tt_____ short=___tt______
Pink body color (P) is dominant to yellow (p).
Pink=___PP or Pp___ yellow=____pp______
5. Use the information for SpongeBob’s traits to write the phenotype for each given genotype.
Trait / Dominant / RecessiveBody Shape / Square (S) / Round (s)
Body Color / Yellow (Y) / Blue (y)
Eye Shape / Round (R) / Oval (r)
Nose Style / Long (L) / Stubby (l)
a. LL-___Long nose____ e. Rr__Round eyes___
b. yy-__Blue body_ f. ll-__Stubby nose____
c. Ss-__Square body__ g. ss-__Round body__
d. RR-_Round eyes_ h. Yy-__Yellow body___
6. Determine the genotypes for each using the information in the chart above.
a. Heterozygous round eyes-_Rr_ c. Homozygous stubby nose-_ll_
b. Purebred SquarePants-_SS_ d. Hybrid yellow body-_Yy_
7. SpongeBob SquarePants recently met SpongeSusie RoundPants at a dance. SpongeBob is heterozygous for his square shape, but SpongeSusie is round. Create a punnett square to show the possibilities that would result if SpongeBob and SpongeSusie had children.
A. What are the probability percentages for each phenotype?
Square-50%, Round-50%
B. What are the probability percentages for each possible genotype?
Ss-50%, ss-50%
C. What is the probability in a percentage of the offspring being heterozygous?
There is a 50% chance for heterozygous offspring.
8. Patrick met Patti at a dance. Both of them are heterozygous for their pink body color, which is dominant over yellow body color. Create a punnett square to show the possibilities that would result if Patrick and Patti had children.
A. What are the probability percentages for each phenotype?
Pink-75%, yellow-25%
B. What are the probability percentages for each possible genotype?
PP-25%, Pp-50%, pp-25%
C. What is the probability (in a percentage) of the offspring being homozygous recessive?
There is a 25% chance for a homozygous recessive genotype.
9. Everyone on Squidward’s family has blue skin, which is the dominant trait for body color. His family brags they are a “purebred” line. He recently married a nice girl who had green skin which is the recessive trait. Create a punnett square to show the possibilities that would result of Squidward and his new wife had children.
A. Could any of Squidward’s children brag they are purebred for the trait of being blue? Why?
No, they would all be hybrids now since they have one blue allele and one green allele. They do not have two blue alleles which would make them purebred.
10. Mr. Krabbs and his wife just had a little baby krab, but it has not been a happy occasion for them. Mrs. Krabbs has been upset since she first saw her new baby who has short eyeballs. She claims the hospital has goofed and mixed her baby with someone else’s baby. Mr. Krabbs is homozygous for his tall eyeballs while his wife is heterozygous for her tall eyeballs. Some members of her family have short eyeballs, which is the recessive form of the trait. Create a Punnett square to figure out if the hospital made a mistake.
A. Did the hospital make a mistake? __Yes_ Explain how you know. Looking at the Punnett square, there is no possibility for Mr. and Mrs. Krabbs to have an offspring with the recessive form of the trait. In fact, it doesn’t even matter what genotype Mrs. Krabbs has since Mr. Krabbs is purebred for his tall eyes. He can only pass on tall alleles to the offspring so there is no way for the offspring to have short eyes.
11. Patrick and Patti finally got married (once SpongeBob got married, Patrick became more serious about life and decided to settle down.) Both Patrick and Patti are hybrid for their tall heads. When they had their first little baby star, they were shocked to see it had a short head which is recessive. Since they don’t know anything about genetics, they are asking for help. Create a Punnett square to see if the hospital actually made a mistake.
A. Did the hospital make a mistake? _No_
B. Explain to the new parents how it is possible for them to make a short head offspring. Patrick and Patty were both hybrid for tall head, so they both have a short head allele that they are carrying. Since they each pass along one allele to the offspring, there is a 25% chance they could have a short head baby.
12. SpongeBob’s snail Gary just met a cute snail named Wilma. Wilma has a red shell which is the dominant form of shell color.
a. If Wilma’s father is a heterozygous red shell snail and her mother has a blue shell which is the recessive form of the trait, what is Wilma’s genotype?
Wilma’s Genotype:___Rr____
b. Gary is hybrid for his red shell. What is his genotype? __Rr___
c. Create a punnett square to show the possibilities if Gary and Wilma had baby snails.
d. List the possible genotypes and phenotypes for the kids. RR, Rr-red, rr-blue
e. What is the probability of snails with red shells? With blue shells? 75% chance for red, 25% chance for blue