In the Fruit Fly,Drosophila Melanogaster,a Spineless (No Wing Bristles)female Fly

question 9

Essay

In the fruit fly,Drosophila melanogaster,a spineless (no wing bristles)female fly is mated to a male that is claret (dark eyes)and hairless (no thoracic bristles).Phenotypically wild-type F₁ female progeny were mated to fully homozygous (mutant)males,and the following progeny (1000 total)were observed:
$\begin{array}{lc}\text { Phenotypes } & \text { Number Observed } \\\hline \text { spineless } & 321 \\\text { wild-type } & 38 \\\text { claret, spineless } & 130 \\\text { claret } & 18 \\\text { claret, hairless } & 309 \\\text { hairless, claret, spineless } & 32 \\\text { hairless } & 140 \\\text { hairless, spineless } & 12\end{array}$
(a)Which gene is in the middle?
(b)With respect to the three genes mentioned in the problem,what are the genotypes of the homozygous parents used in making the phenotypically wild-type F? heterozygote?
(c)What are the map distances for the three genes? A correct formula with the values "plugged in" for each distance will be sufficient.
(d)What is the coefficient of coincidence? A correct formula with the values "plugged in" will be sufficient.

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Definitions:

Triple X Syndrome

Chromosomal disorder in which an individual is born with three X chromosomes; often unnoticed.

Klinefelter Syndrome

A genetic condition affecting males, characterized by an extra X chromosome, leading to symptoms such as reduced fertility and physical differences.

Fragile X Syndrome

A genetic disorder characterized by intellectual disability, behavioral challenges, and certain physical traits, caused by mutation in the FMR1 gene.

XYY Syndrome

A genetic condition in which a male has an extra Y chromosome, often associated with tall stature and, in some cases, subtle learning difficulties or behavioral issues.