kernel phenotype Number
colored, shrunken, starchy 116
colored, full, starchy 601
colored, full, waxy 2538
colored, shrunken, waxy 4
colorless, shrunken, starchy 2708
colorless, full, starchy 2
colorless, full, waxy 113
colorless, shrunken, waxy 626
total 6708
Researchers cross a corn plant that is pure-breeding for the dominant traits colored aleurone (C1), full kernel (Sh), and waxy endosperm (Wx) to a pure-breeding plant with the recessive traits colorless aleurone (c1), shrunken kernel (sh), and starchy (wx).
The resulting F1 plants were crossed to pure-breeding colorless, shrunken, starchy plants. Counting kernels from about 30 ears of corn yields the data shown in the table.
Question: What is the order of these genes in corn?
A. The gene order is Cl-Sh-Wx.
B.The gene order is Cl-Wx-Sh.
C. The gene order is Sh-Cl-Wx.
D. Pleiotropy
E. None of the Above?
Question 2:Question: What is the calculated distance in map units (number, rounded off to 1 decimal place: example 12.3) between the genes Cl and Sh?
Question3: What is the calculated distance in map units (number, rounded off to 1 decimal place: example 12.3) between the genes Sh and Wx?
Question 4: What is the calculated distance in map units (number, rounded off to 1 decimal place: example 12.3) between the genes Cl and Wx?
To determine the gene order in corn, we can analyze the data provided in the table. Let's break down the information and calculate the distances between the genes.
First, let's look at the F1 generation resulting from the cross between the pure-breeding plants with dominant and recessive traits:
- The "colored" phenotype is dominant (C1) and the "colorless" phenotype is recessive (c1).
- The "full" kernel phenotype is dominant (Sh) and the "shrunken" kernel phenotype is recessive (sh).
- The "waxy" endosperm phenotype is dominant (Wx) and the "starchy" endosperm phenotype is recessive (wx).
Now, let's examine the data:
- There are 116 kernels with colored, shrunken, and starchy phenotypes.
- There are 601 kernels with colored, full, and starchy phenotypes.
- There are 2538 kernels with colored, full, and waxy phenotypes.
- There are 4 kernels with colored, shrunken, and waxy phenotypes.
- There are 2708 kernels with colorless, shrunken, and starchy phenotypes.
- There are 2 kernels with colorless, full, and starchy phenotypes.
- There are 113 kernels with colorless, full, and waxy phenotypes.
- There are 626 kernels with colorless, shrunken, and waxy phenotypes.
Based on this data, we can determine the gene order. Let's look at the phenotypes of the kernels:
- The presence of the colored allele (C1) is consistent in all the colored kernels.
- The presence of the shrunken allele (sh) is consistent in all the shrunken kernels.
- The presence of the starchy allele (wx) is consistent in all the starchy kernels.
Therefore, the order of the genes in corn is C1-sh-wx.
Now, let's move on to the calculated distances between the genes:
Question 2: To determine the distance between the genes Cl and Sh (C1 and sh), we need to look at the colored and shrunken kernels. We have 116 colored, shrunken, and starchy kernels, and a total of 6708 kernels. The formula to calculate the distance is (number of recombinant kernels / total number of kernels) * 100.
- Recombinant kernels in this case are colored, shrunken, and starchy (116).
- Distance = (116 / 6708) * 100 = 1.73 (rounded to 1 decimal place).
Therefore, the distance between the genes Cl and Sh is approximately 1.7 map units.
Question 3: To determine the distance between the genes Sh and Wx (sh and wx), we need to look at the shrunken and waxy kernels. We have 4 colored, shrunken, and waxy kernels and a total of 6708 kernels.
- Recombinant kernels in this case are colored, shrunken, and waxy (4).
- Distance = (4 / 6708) * 100 = 0.06 (rounded to 1 decimal place).
Therefore, the distance between the genes Sh and Wx is approximately 0.1 map units.
Question 4: To determine the distance between the genes Cl and Wx (C1 and wx), we need to add up the recombinant kernels from Cl-Sh and Sh-Wx (shrunken).
- Recombinant kernels from Cl to Sh = 116 (as calculated above).
- Recombinant kernels from Sh to Wx = 4 (as calculated above).
- Total recombinant kernels = 116 + 4 = 120.
- Distance = (120 / 6708) * 100 = 1.79 (rounded to 1 decimal place).
Therefore, the distance between the genes Cl and Wx is approximately 1.8 map units.
In summary:
- The gene order is Cl-Sh-Wx.
- The distance between the genes Cl and Sh is approximately 1.7 map units.
- The distance between the genes Sh and Wx is approximately 0.1 map units.
- The distance between the genes Cl and Wx is approximately 1.8 map units.