Question

bikini bottom genetics
scientists at bikini bottoms have been investigating the genetic makeup of the organisms in this community.
use the information provided and your knowledge of genetics to answer each question.

1. for each genotype below, indicate whether it is a heterozygous (he) or homozygous (ho).

tt __ bb dd ff tt dd __
dd __ ff tt bb bb ff __
which of the genotypes in #1 would be considered purebred? ____________________
which of the genotypes in #1 would be hybrids? ____________________

1. determine the phenotype for each genotype using the information provided about spongebob.

yellow body color is dominant to blue.
yy __________ yy ________ yy __________
square shape is dominant to round.
ss __________ ss ________ ss __________

1. for each phenotype, give the genotypes that are possible for patrick.

a tall head (t) is dominant to short (t).
tall = __________ short = __________
pink body color (p) is dominant to yellow (p).
pink body = __________ yellow body = __________

1. 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. hint: read question #2!

a. list the possible genotypes and phenotypes for their children.
b. what are the chances of a child with a square shape? __ out of or __%
c. what are the chances of a child with a round shape? __ out of or __%

1. patrick met patti at the dance. both of them are heterozygous for their pink body color, which is dominant over a yellow body color. create a punnett square to show the possibilities that would result if patrick and patti had children. hint: read question #3!

a. list the possible genotypes and phenotypes for their children.
b. what are the chances of a child with a pink body? __ out of or __%
c. what are the chances of a child with a yellow body? __ out of or __%
t. trimpe 2003 http://sciencespot.net/

Explanation:

Step1: Classify genotypes (Hetero/Homo)

Homozygous (Ho) = identical alleles; Heterozygous (He) = different alleles

• TT: Ho, Bb: He, DD: Ho, Ff: He, tt: Ho, dd: Ho
• Dd: He, ff: Ho, Tt: He, bb: Ho, BB: Ho, FF: Ho

Step2: Identify purebred/hybrid genotypes

Purebred = homozygous; Hybrid = heterozygous

• Purebred: TT, DD, tt, dd, ff, bb, BB, FF
• Hybrids: Bb, Ff, Dd, Tt

Step3: Match genotypes to phenotypes (SpongeBob)

Yellow (Y) dominant over blue (y); Square (S) dominant over round (s)

• YY: Yellow body, Yy: Yellow body, yy: Blue body
• SS: Square shape, Ss: Square shape, ss: Round shape

Step4: List possible genotypes (Patrick)

Tall (T) dominant over short (t); Pink (P) dominant over yellow (p)

• Tall: TT, Tt; Short: tt
• Pink body: PP, Pp; Yellow body: pp

Step5: SpongeBob × SpongeSusie Punnett Square

SpongeBob: Ss (heterozygous square); SpongeSusie: ss (round)
Gametes: SpongeBob = S, s; SpongeSusie = s, s
Punnett Square:

	S	s
s	Ss	ss

• Genotypes: Ss, ss; Phenotypes: Square, Round
• Square chance: $\frac{2}{4}$ = 50%
• Round chance: $\frac{2}{4}$ = 50%

Step6: Patrick × Patti Punnett Square

Both: Pp (heterozygous pink)
Gametes: P, p for both
Punnett Square:

	P	p
p	Pp	pp

• Genotypes: PP, Pp, pp; Phenotypes: Pink body, Yellow body
• Pink body chance: $\frac{3}{4}$ = 75%
• Yellow body chance: $\frac{1}{4}$ = 25%

Answer:

1.

• TT: Ho, Bb: He, DD: Ho, Ff: He, tt: Ho, dd: Ho
• Dd: He, ff: Ho, Tt: He, bb: Ho, BB: Ho, FF: Ho
• Purebred: TT, DD, tt, dd, ff, bb, BB, FF
• Hybrids: Bb, Ff, Dd, Tt

2.

• YY: Yellow body, Yy: Yellow body, yy: Blue body
• SS: Square shape, Ss: Square shape, ss: Round shape

3.

• Tall: TT, Tt; Short: tt
• Pink body: PP, Pp; Yellow body: pp

4.
A. Genotypes: Ss, ss; Phenotypes: Square shape, Round shape
B. 2 out of 4 or 50%
C. 2 out of 4 or 50%

5.
A. Genotypes: PP, Pp, pp; Phenotypes: Pink body, Yellow body
B. 3 out of 4 or 75%
C. 1 out of 4 or 25%