The allele for having brown eyes is B and the allele for having green eyes is b. Imagine a mother that is heterozygous for brown eyes and a father that has green eyes. Use this information to answer the following questions. (HINT: use a piece of scratch paper to create a Punnett Square)
1. What is the genotype of the mother?
2. What is the genotype of the father?
3. What are the possible genotypes of the offspring?
4. What is the genotypic ratio?
5. Is it possible for one of the offspring to be homozygous dominant? Why or why not?
1. What is the genotype of the mother?
2. What is the genotype of the father?
3. What are the possible genotypes of the offspring?
4. What is the genotypic ratio?
5. Is it possible for one of the offspring to be homozygous dominant? Why or why not?
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You have to think backwards,
1. heterozygous means a hybrid, so the mother must have Bb.
2. Since green eyes is recessive, the dad must have a bb genotype to express the recessive gene.
3. If you draw out your Punnett square, the possible genotypes are a) Bb b) bb c)Bb d)bb.
4. The genotypic ratio is made by looking how many times each genotype is likely to occur. 2 for Bb, and 2 for bb, which makes the ratio 2:2, simplified to 1:1.
5. Since homozygous means the same, the gene that they are asking for is BB. This can only occur if both parents have the dominate allele, which the dad doesn't. Therefore BB is not possible.
1. heterozygous means a hybrid, so the mother must have Bb.
2. Since green eyes is recessive, the dad must have a bb genotype to express the recessive gene.
3. If you draw out your Punnett square, the possible genotypes are a) Bb b) bb c)Bb d)bb.
4. The genotypic ratio is made by looking how many times each genotype is likely to occur. 2 for Bb, and 2 for bb, which makes the ratio 2:2, simplified to 1:1.
5. Since homozygous means the same, the gene that they are asking for is BB. This can only occur if both parents have the dominate allele, which the dad doesn't. Therefore BB is not possible.
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1. Bb
2. bb
3. Bb, Bb, bb, bb
4. 2:2
5. No. The only way the offspring could be homozygous dominant is if the parents had one of these combinations:
1. One parent homozygous dominant and the other heterozygous.
2. Both homozygous dominant
3. Both heterozygous.
2. bb
3. Bb, Bb, bb, bb
4. 2:2
5. No. The only way the offspring could be homozygous dominant is if the parents had one of these combinations:
1. One parent homozygous dominant and the other heterozygous.
2. Both homozygous dominant
3. Both heterozygous.
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1. Bb
2. bb
3. Bb, Bb, bb, bb
4. Meh. I don't know.
5. Yes, because both parents have genes for green eyes.
2. bb
3. Bb, Bb, bb, bb
4. Meh. I don't know.
5. Yes, because both parents have genes for green eyes.