a mutant screen in Drosophila, you identified a gene related to memory, as evidenced by the inability of recessive homozygotes to learn to associate a particular scent with the availability of food. Given another line of flies with an autosomal mutation that produces orange eyes, design a series of crosses to determine the map distance between these two loci. You do not need to calculate recombination frequency.

First used in Drosophila, recombination frequencies can help map relative positions of genes along chromosomes. The greater the distance between two loci on a single chromosome, the greater the chance that they will be separated by a crossing-over event during meiosis I. If two genes are recombined in x% of gametes, they are separated by a genetic map distance of xmap units. In humans, such mapping located disease-causing mutations near single-nucleotide polymorphisms (SNPS). Recombination frequencies among six Drosophila chromosome genes (yellow-body (yb), white-eye (we), singed-bristle (sb), miniature wings (mw), round eyes (re), and hairy body (hb) are given in the table below. Using this information, place the genes in the correct relative order along the chromosome. Genes we and yb have been filled in to get you started. we yb sb mw re hb we 1.4 19.6 34.7 6.1 12.3 yb 1.4 21 36.1 7.5 13.7 sb 19.6 21 15.1 13.5 7.3 mw 34.7 36.1 15.1 28.6 22.4 re 6.1 7.5 13.5 28.6 6.2 hb 12.3 13.7 7.3…

You are working with a hypothetical fly and have found color and wing mutants. Preliminary work indicates that the mutant traits are recessive and the associated genes are not sex-linked, but beyond that, you have no information. You first look at 2 genes, each with 2 alleles. "B" or “b" for body color and "W" or "w" for wing surface. The red-body phenotype is dominant to the yellow-body phenotype and smooth wings are dominant to crinkled wings.

In the fruit fly, dumpy wings (d) and purple eyes (p) are encoded by mutant alleles that are recessive to those that produce wild type traits; long wings (d+) and red eyes (p+). These two genes are on the same chromosome. In a particular lab, two researchers Walt and Jesse crossed a fly homozygous for dumpy wings and purple eyes with a fly homozygous for the wild type traits. The F1 progeny, which had long wings and red eyes, was then crossed with flies that had dumpy wings and purple eyes. Unfortunately, the progeny of this cross somehow escaped. To prevent their other projects from contamination, they decided to spend an exceptionally boring hour in the lab catching and counting the progeny and found the following:   long wings, red eyes – 482 dumpy wings, purple eyes – 473 long wings, purple eyes – 23 dumpy wings, red eyes - 22   What is the genetic distance between these two loci? a. 4.5 cM b. 55 cM c. 45 cM d. 49.5 cM  e. 4.7 cM