The data presented in Figure 2 below is for a gene that has a standard Mendelian transmission. This disease is only seen in the world at the rate of about 1 in XXXXXXXXXXbirths. However, in an...

1. The following is data from a cross of a heterozygous drosophila female and a
homozygous recessive male. The data is examining three linked genes. Use the data
to determine:
a.The order of the genes on the chromosome.
b. The pattern of the genes on the female’s pair of chromosomes.
c. The map distances between the genes.
Table 1 Drosophila Cross data 1000 F1 progeny scored for 3 linked loci
Trait number
Smooth abdomen(sa) 87
Lobe Eye(le) and withered wings (ww) 76
Lobe eye (le) 2
withered wings and smooth abdomen 3
Wild type(+, +, +) 353
Lobe eyes, withered wings and smooth
abdomen
307
Withered wings 45
Lobe eyes and smooth abdomen 53
This is a three point test cross with 3 linked loci: smoothed abdomen (sa), lobe eye (le), withered wing
(ww).
To examine gene mapping with a three-point testcross, we have to consider three recessive mutations
in the fruit fly Drosophila melanogaster. Here following three mutations are taken
Smoothed abdomen (sa)
Lobe eye (le)
Withered wing (ww)
The cross can be presented in following way:

x

These genes can be located in trans configuration or in cis configuration. The order of these three loci is
arbitrarily assigned here, because the middle gene is unknown.
Determination of the gene order:
To map the genes gene order must be known. This can be determined in following way
 First, determine the nonrecombinants progeny — they will be the two most-numerous
classes’ progeny. (Even if crossing over takes place in every meiosis, the
nonrecombinants will constitute at least 50% of the progeny.)
The data given here the most numerous progeny are wild type (+ + +)
and smoothed abdomen, lobed eye, withered wing (sa le ww)
 Next, identify the double-crossover progeny. These progeny should...