As a research scientist at Kellogg’s, you are interested in ensuring that your crop of rice conforms to traditional properties found in the legendary Rice Crispy cereal. Three genes, Snap (s), Crackle (c), and Pop (p) control carbohydrate metabolism in rice. Your job is to learn a bit more about these genes. You testcross a triple heterozygote SsCcPp rice plant and examine the progeny of this cross with the following results:
| Phenotype | Number of progeny |
| WT | 61 |
| s | 144 |
| c | 681 |
| p | 8 |
| sc | 12 |
| cp | 132 |
| sp | 701 |
| scp | 53 |
a. What is the gene order of these three genes? Not case sensitive. Just list three letters with no spaces
b. What is the allele configuration in the heterozygote? Enter in the format SCP/SCP. Gene order, case sensitive, and no spaces should be entered
c. What is the map distance between the first two genes?
d. What is the map distance between the second two genes?
e. What is the value of interference at this locus?
2. You are studying two mutations in pumpkins. The wild type allele of the orange (O_) gene is dominant and causes green coloring while the mutant allele (oo) results in orange pumpkins. The wild type allele of the giant (G_) gene generates small pumpkins while the mutant allele (gg) generates county fair worthy monster pumpkins. You are interested in figuring out whether these genes are linked so you cross a true breeding monster green pumpkin with a true breeding orange pumpkin of typical size. The F1 pumpkins are all green and of typical size. Youtestcross these F1 pumpkins with monster orange pumpkins and get the following results.
| Phenotype | Observed progeny |
| Small, Green | 854 |
| Moster, Green | 891 |
| Small, Orange | 921 |
| Moster, Orange | 832 |
Using chi square analysis, determine if the genes are linked.
a. Show the genotype illustrating the parental configuration in the F1 heterozygote using the format (OG/OG) where obviously it is case sensitive. No spaces!
b. What is the total progeny formed by parental gametes?
c. What is the total progeny formed by non-parental “recombinant” gametes
d. Are the genes linked? (just enter yes or no)
3. The coat color in mink is controlled by two codominant alleles at the “R” locus. Red coat color is produced by the genotype R1R1, silver coat by the genotype R1R2, and platinum color by R2R2. White spotting of the coat is a recessive trait found with the genotype ss. Solid coat color is found with the S- genotype.
Part A: What are the expected progeny phenotypes and proportions for the cross SsR1R2 x ssR2R2? Enter your result as a frequency (between 0 & 1).
| Spotted, platinum | Spotted, silver | Spotted, red | Solid, platinum | Solid, silver | Solid, Red | |
| Frequency |
Part B: If the cross SsR1R2 x SsR1R1 is made, what are the progeny phenotypes, and in what proportions are they expected to occur? Enter your result as a frequency (between 0 & 1).
| Spotted, platinum | Spotted, silver | Spotted, red | Solid, platinum | Solid, silver | Solid, Red | |
| Frequency |
Part C: Two crosses are made between mink.
- Cross 1 is the cross of a solid, silver mink to one that is solid, platinum.
- Cross 2 is between a spotted, silver mink and one that is solid, silver.
The progeny are described in the table below. Use these data to determine the genotypes of the parents in each cross.
| Spotted, platinum | Spotted, silver | Spotted, red | Solid, platinum | Solid, silver | Solid, Red | |
| Cross 1 | 2 | 3 | 0 | 6 | 5 | 0 |
| Cross 2 | 3 | 7 | 2 | 4 | 5 | 3 |
Parents from cross 1
- Solid, silver
- Solid, platinum
Parents from cross 2
- Spotted, silver
- Solid, silver
