In the tomato, red fruit (R) is dominant over yellow fruit (r), and yellow flowers (F) are dominant over white flowers (f). A cross was made between true-breeding plants with red fruit and yellow flowers, and plants with yellow fruit and white flowers. All F1 offspring are heterozygotes for both traits. The F1 female plants were then test crossed to males with yellow fruit and white flowers (homozygous recessive for both traits). The following results were obtained:
333 red fruit, yellow flowers
64 red fruit, white flowers
58 yellow fruit, yellow flowers
345 yellow fruit, white flowers
Total of 800
1. Conduct a Chi square analysis to see if the two genes are linked ( Check a solved problem S1, page 148 in the first edition text book, and page 150 in the second edition problem #1 for an idea)â¦follow the same steps)
a. Propose a hypothesis to be tested
b. Find the expected (predicted) number of offspring ( Hint what is the ratio of test cross results?)
c. Calculate and Interpret the Chi âsquare result
d. If the two genes (fruit color and flower color) are linked, calculate the map distance between the two genes.
2. Set a sample test cross, Explain the rationale behind a testcross, why is it necessary for one of the parents to be homozygous recessive for the genes of interest?
In the tomato, red fruit (R) is dominant over yellow fruit (r), and yellow flowers (F) are dominant over white flowers (f). A cross was made between true-breeding plants with red fruit and yellow flowers, and plants with yellow fruit and white flowers. All F1 offspring are heterozygotes for both traits. The F1 female plants were then test crossed to males with yellow fruit and white flowers (homozygous recessive for both traits). The following results were obtained:
333 red fruit, yellow flowers
64 red fruit, white flowers
58 yellow fruit, yellow flowers
345 yellow fruit, white flowers
Total of 800
1. Conduct a Chi square analysis to see if the two genes are linked ( Check a solved problem S1, page 148 in the first edition text book, and page 150 in the second edition problem #1 for an idea)â¦follow the same steps)
a. Propose a hypothesis to be tested
b. Find the expected (predicted) number of offspring ( Hint what is the ratio of test cross results?)
c. Calculate and Interpret the Chi âsquare result
d. If the two genes (fruit color and flower color) are linked, calculate the map distance between the two genes.
2. Set a sample test cross, Explain the rationale behind a testcross, why is it necessary for one of the parents to be homozygous recessive for the genes of interest?
Related textbook solutions
Related questions
**2 questions, Can someone help explain the firstquestion. The second one, I just need someone to help see if I didit right.
Tomato Plants
In tomato plants, round fruit (R) is dominant to oval fruit(r). Pure breeding plants with red and round fruit(FFRR) were crossed to pure breeding plants with yellowand oval fruit (ffrr).
The red and round F1 progeny were then testcrossed toplants that were homozygous recessive for both genes(ffrr) with the following results:
| Phenotypes | Number of Offspring |
|---|---|
| Red and round | 2 255 |
| Red and oval | 290 |
| Yellow and round | 310 |
| Yellow and oval | 2 145 |
Complete a Punnett square to determine the expected testcrossprogeny on the basis of Mendelâs Law of Independent Assortment.
Tomato Plant Leaves
In tomatoes, regular leaves (L) are multilobed andserrated and potato leaves (l) are broad, smooth, andsingle (Image 1). Red fruit (F) is dominant toyellow fruit (f).
A cross is carried out between two pure lines of tomato plants,one having regular leaves and red fruit and the other having potatoleaves and yellow fruit. The F1 generation all haveregular leaves and red fruit. TheF1 individuals are then crossed with one another.
Complete a Punnett square to determine the expectedF2 progeny on the basis of Mendelâs Law of IndependentAssortment, which states that the alleles for one gene segregateindependently of the alleles for other genes during gameteformation.
| RL | Rl | rL | rl | |
| RL | RRLL | RRLl | RrLL | RrLl |
| Rl | RRLl | RRll | RrLl | Rrll |
| rL | RrLL | RrLl | rrLL | rrLl |
| rl | RrLl | Rrll | rrLl | rrll |
*******************Did I get the right F1? RrLlxRrLl?
Is my punnett square correct? If not, can someone explain
