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Punnett Square

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Solve all of these problems using a Punnett Square. If you cannot reproduce the square using software, then you may do them by hand and scan in the image of your solution and submit all images in the one document.

In certain bacteria, an oval shape (A) is dominant over round (a) and thick cell walls (B) are dominant over thin (b). A bacteria heterozygous for both oval shape and a thick cell wall was crossed with a round bacteria with a thin cell wall. Describe the phenotype of the offspring.

The ability to roll the tongue sideways (A) is dominant over the inability to roll one's tongue (a). In humans, non-attached earlobes (B) are dominant over attached earlobes (b). Two parents with attached earlobes can roll their tongues. They are both heterozygous for the tongue rolling trait.
What is the genotype of the mother?
What is the genotype of the father?
What are the possible gametes from the mother?
What are the possible gametes from the father?
Draw the Punnett square, and combine the gametes to produce offspring
What is the phenotypic ratio of these offspring?

A man heterozygous for non-attached earlobes can roll his tongue. A woman with attached earlobes can roll her tongue. Assume both are heterozygous for the tongue-rolling trait.
What is the genotype of the mother?
What is the genotype of the father?
What are the possible gametes from the mother?
What are the possible gametes from the father?
Draw the Punnett square, and combine the gametes to produce offspring
What is the phenotypic ratio of these offspring?

In summer squash, white fruit color (W) is dominant over yellow fruit color (w) and disk-shaped fruit (D) is dominant over sphere-shaped fruit (d). If a squash plant purebreeding for white and purebreeding for disk-shaped fruit is crossed with a plant purebreeding for yellow, sphere-shaped fruit, what will the phenotypic and genotypic ratios be for:
the F1 generation?
the F2 generation?

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In certain bacteria, an oval shape (A) is dominant over round (a) and thick cell walls (B) are dominant over thin (b). A bacteria heterozygous for both oval shape and a thick cell wall was crossed with a round bacteria with a thin cell wall. Describe the phenotype of the offspring.

bacteria heterozygous for both oval shape and a thick cell wall: AaBb
round bacteria with a thin cell wall: aabb
For dihybrid crosses, need to figure out the total possible combinations of alleles that would be found in a gamete for that individual - for example, take the AaBb bacteria. You can have AB, Ab, aB, or ab found in gametes (of course, bacteria don't make gametes, but the idea still holds here). You do this for each individual and then place the allele combinations where you would normally put the parental gametes in the Punnett ...

Solution Summary

Punnett Square is carefully applied in the solution.

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