Individuals with the following genotypes are crossed: Aa Bb Cc Dd x Aa Bb Cc Dd. Alleles of these four genes/loci assort independently of one another. Give the proportion of the progeny of this cross that are expected to have each of the following genotypes:
a) Aa Bb Cc Dd
b) aa bb cc dd
c) Aa Bb cc Dd
For help with this problem:
Begin by thinking about the steps to take to do this problem. Use the dropdown menu to put the steps in the order in which they should be performed.
| Use the multiplication rule to calculate the probabilities of the requested genotype combinations. | TzpCiTTG0iXU9nS9u3dB5QZLD5Q= |
| Choose a problem-solving approach. | 69jF8Px+4GGQFuUqcGp08dUuipU= |
| Identify the question being asked. | cRtjCbXxabz7qd/Cr9V0Nx1VWJw= |
| Define terms you may not know or understand. | ExCWzMuuu14xmOkhmrHn1xzoll0= |
| Identify relevant information in the problem that will enable you to answer the question. | T7aBxMvLDtMmPFr9J1aYxALf21A= |
| For each of the four loci, calculate the probabilities of each possible genotype among the progeny. | ZXSKd6tc5cZMOOTHzn4uFkFfMRs= |
Do you understand all the terms used in the question? What question is being asked? What would you do next after figuring out these first two steps? For the last two steps, which needs to be calculated before the other: individual probabilities or combined probabilities?
Review the definitions of genes, alleles, and locus/loci in your text. See Table 3.1 on Page 48.
Are you given genotype or phenotype information in the question? Are you being asked to figure out the geno-/phenotypes or their proportions?
Are you given genotype or phenotype information in the question? Are you being asked to figure out the geno-/phenotypes or their proportions?
Consider the type of cross that is involved in this problem. It is not a monohybrid or dihybrid cross, so some problem-solving approaches will not be practical. Next, determine whether you should use the multiplication rule or the addition rule to calculate the requested combined genotypic frequencies. Finally, determine if you need to test whether the expected and observed values are statistically significantly different using a chi-square goodness-of-fit test.
This information is given in the problem statement. Reread it if you’re unsure of the answer.
Because this part of the problem is a simple monohybrid cross, you can draw a small Punnett square to calculate the probabilities for this locus alone.
| A | a | |
| A | AA | Aa |
| a | Aa | aa |
This information is given in the problem statement. Reread it if you’re unsure of the answer.
Because this part of the problem is a simple monohybrid cross, you can draw a small Punnett square to calculate the probabilities for this locus alone.
| B | b | |
| B | BB | Bb |
| b | Bb | bb |
This information is given in the problem statement. Reread it if you’re unsure of the answer.
Because this part of the problem is a simple monohybrid cross, you can draw a small Punnett square to calculate the probabilities for this locus alone.
| C | c | |
| C | CC | Cc |
| c | Cc | cc |
This information is given in the problem statement. Reread it if you’re unsure of the answer.
Because this part of the problem is a simple monohybrid cross, you can draw a small Punnett square to calculate the probabilities for this locus alone.
| D | d | |
| D | DD | Dd |
| d | Dd | dd |
1. For the first requested genotypic combination of Aa Bb Cc Dd, use the proportions you calculated for each locus in step 5 to calculate the combined proportion among the offspring. Use fractions (e.g., 1/256) rather than decimals to do your calculations.
probability of Aa among offspring PTqa6FnHcN0=
x probability of Bb among offspring PTqa6FnHcN0=
x probability of Cc among offspring PTqa6FnHcN0=
x probability of Dd among offspring PTqa6FnHcN0=
= yWj6n8fDcws= combined probability of Aa Bb Cc Dd
Be sure you use the specific probability for each of the genotypes that are requested in the problem. Use the multiplication rule to calculate the combined probability.
2. For the second requested genotypic combination of aa bb cc dd, use the proportions you calculated for each locus in step 5 to calculate the combined proportion among the offspring. Use fractions rather than decimals to do your calculations.
probability of aa among offspring OyEyyWtwUGw=
x probability of bb among offspring OyEyyWtwUGw=
x probability of cc among offspring OyEyyWtwUGw=
x probability of dd among offspring OyEyyWtwUGw=
= cREBgSN22Qvc+muU combined probability of aa bb cc dd
Be sure you use the specific probability for each of the genotypes that are requested in the problem. Use the multiplication rule to calculate the combined probability. Follow the same process you used in question 1 directly above.
3. For the third requested genotypic combination of Aa Bb cc Dd, use the proportions you calculated for each locus in step 5 to calculate the combined proportion among the offspring.
probability of Aa among offspring PTqa6FnHcN0=
x probability of Bb among offspring PTqa6FnHcN0=
x probability of cc among offspring OyEyyWtwUGw=
x probability of Dd among offspring PTqa6FnHcN0=
= im6LnJb5bk4= combined probability of Aa Bb cc Dd
Be sure you use the specific probability for each of the genotypes that are requested in the problem. Use the multiplication rule to calculate the combined probability. Follow the same process you used in questions 1 & 2 directly above.