In cucumbers, dull fruit (D) is dominant to glossy fruit (d), and orange fruit (R) is dominant to cream (r) fruit. The genes coding for dull and glossy assort independently from the genes coding for orange and cream. A plant that has dull and orange fruits is crossed to a plant that has dull and cream fruits. The cross produces 3⁄8 plants with dull and orange fruits, 3⁄8 plants with dull and cream fruits, 1⁄8 plants with glossy and orange fruits, and 1⁄8 plants with glossy and cream fruits. Give the genotypes of the parents and offspring of the cross.
Generation | Genotypes | ||
---|---|---|---|
P | × | ||
↓ | |||
F1 | |||
What information is the problem asking you to provide? (check all that apply)
The phenotypes of the parents. | |
The phenotypic ratios of the progeny. | |
The genotypes of parents and progeny. | |
Genotypic ratios of the progeny. |
Outline the phenotypes of the parents and offspring by choosing from the drop-down menus below.
Generation | Phenotypes | ||
---|---|---|---|
P | × | ||
↓ | |||
F1 | 3⁄8 | ||
3⁄8 | |||
1⁄8 | |||
1⁄8 |
Give the allelic symbols to be used for each trait:
Texture | |
---|---|
dull | |
glossy |
Color | |
---|---|
orange | |
cream |
Now determine what you know about the allelic symbols for the genotypes of the parents, using only what you know from the phenotypes given in the question (not the progeny) to guide you. Use an underscore (_) to indicate any genes you feel you can not ascertain from the phenotypes.
On the basis of its phenotype, which is the correct genotype for the dull, orange parent?
A. |
B. |
C. |
D. |
Now determine what you know about the allelic symbols for the genotypes of the progeny. Use an underscore (_) to indicate any genes you can not ascertain from the phenotypes.
On the basis of its phenotype, which is the correct genotype for the glossy, cream offspring?
A. |
B. |
C. |
D. |
The next step in solving the problem is to separate the cross into two single-locus crosses, looking at the inheritance of each trait by itself. Let's start with the texture characteristic.
First assemble the relevant information. In the table below fill in again what we know about the texture alleles for parents and progeny based solely on the information given directly in the question:
Generation | Genotypes | ||
---|---|---|---|
P | × | ||
↓ | |||
F1 | 3⁄8 | ||
3⁄8 | |||
1⁄8 | |||
1⁄8 |
Now let's consider the color characteristic.
First assemble the relevant information. In the table below fill in again what we know about the color alleles for parents and progeny based solely on the information given directly in the question:
Generation | Genotypes | ||
---|---|---|---|
P | × | ||
↓ | |||
F1 | 3⁄8 | ||
3⁄8 | |||
1⁄8 | |||
1⁄8 |
Now put it all together and try filling in the whole table again:
Generation | Genotypes | ||
---|---|---|---|
P | × | ||
↓ | |||
F1 | |||