![Genetic Analysis: An Integrated Approach (2nd Edition)](https://www.bartleby.com/isbn_cover_images/9780321948908/9780321948908_largeCoverImage.gif)
Concept explainers
A
a. Determine the gene order and identify the alleles on thehomologous X chromosomes in the trihybrid females.
b. Calculate the recombination frequencies between eachof the gene pairs.
c. Compare the recombination frequencies and speculateabout the source of any apparent discrepancies in therecombination data.
d. Use
![Check Mark](/static/check-mark.png)
Want to see the full answer?
Check out a sample textbook solution![Blurred answer](/static/blurred-answer.jpg)
Chapter 5 Solutions
Genetic Analysis: An Integrated Approach (2nd Edition)
- In Drosophila, a heterozygous female for the X-linkedrecessive traits a, b, and c was crossed to a male that phenotypically expressed a, b, and c. The offspring occurred inthe following phenotypic ratios.+ b c 460a + + 450a b c 32+ + + 38a + c 11+ b + 9 No other phenotypes were observed.(a) Determine the correct sequence and construct amap of these genes on the X chromosome ?arrow_forwardThree recessive mutations in that affect eye colour, wing shape and body colourarew, m and b. The following numbers were obtained for testcross progeny in Drosophila. Number Phenotype + m + w + b + + b w m + m b 218 236 168 178 95 101 w + + + 3 w mb 1 (i) Determine the chromosomal composition of the heterozygous female parent. Construct a genetic map of the linkage group(s) these genes occupy. Show the order and give the map distances between the genes. (ii)arrow_forwardMale Drosophila from a true-breeding wild-type stock were irradiated with X-rays and then mated with females from a true-breeding stock carrying the following recessive mutations on the X chromosome: yellow body (y), crossveinless wings (cv), cut wings (ct), singed bristles (sn), and miniature wings (m). These markers are known to map in the order: Recessive alleles: y, cv, ct, sn, m Dominant alleles: y+, cv+, ct+, sn+, m+ y-cv-ct-sn-m у CV ct sn m X-rays х х X ct sn CV у m y+ CV+ ct+ sn+ m+ х X ? Exceptional female: Most of the female progeny of this cross were phenotypically wild type, but one female exhibited ct and sn mutant characteristics. When this exceptional ct sn female was mated with a male from the true-breeding wild-type stock, twice as many females as males appeared among the progeny. a. What is the nature of the X-ray-induced mutation present in the exceptional female? b. Draw the X chromosomes present in the exceptional ct sn female as they would appear during pairing…arrow_forward
- Concordance studies of twins for a neurodegenerative disorder show MZ= 46% and DZ= 15%. Further studies have shown a possible link to a gene on chromosome 9, however, there are some individuals in the study who have the allele but do not develop the disorder (group 1), and there are other individuals who do not have the allele yet develop the disorder (group 2). Amita's older sister and maternal uncle have this disorder. Currently, Amita & her 2 younger brothers do not show symptoms. Amita's paternal grandfather was rumored to have this disorder. 1. Draw the pedigree for Amita's family and determine the mode of inheritance if any. 2. Explain how the 2 groups in the study could be possible? 3. What would you tell Amita about the heritability of this disorder?arrow_forwardThe following list of four Drosophila mutations indicates the symbol for the mutation, the name of thegene, and the mutant phenotype:Allele symbol Gene name Mutant phenotypedwp dwarp small body, warped wingsrmp rumpled deranged bristlespld pallid pale wingsrv raven dark eyes and bodiesYou perform the following crosses with the indicatedresults:Cross #1: dwarp, rumpled females × pallid, raven males→ dwarp, rumpled males and wild-type femalesCross #2: pallid, raven females × dwarp, rumpled males→ pallid, raven males and wild-type femalesF1 females from cross #1 were crossed to males froma true-breeding dwarp rumpled pallid raven stock.The 1000 progeny obtained were as follows:pallid 3pallid, raven 428pallid, raven, rumpled 48pallid, rumpled 23dwarp, raven 22dwarp, raven, rumpled 2dwarp, rumpled 427dwarp 47Indicate the best map for these four genes, includingall relevant data. Calculate interference values whereappropriate.arrow_forwardIn Drosophila, Dichaete (D) is a mutation on chromosome III witha dominant effect on wing shape. It is lethal when homozygous.The genes ebony body (e) and pink eye (p) are recessive mutations on chromosome III. Flies from a Dichaete stock were crossed to homozygous ebony, pink flies, and the F1 progeny with a Dichaete phenotype were backcrossed to the ebony, pink homozygotes. Question: a.) Using the results of this backcross shown in the following table, diagram the cross, showing the genotypes of the parents and offspring of both crosses. b.) What is the sequence and interlocus distance between thesethree genes? Phenotype NumberDichaete 401ebony, pink 389Dichaete, ebony 84pink 96Dichaete, pink 2ebony 3Dichaete, ebony, pink 12wild type 13arrow_forward
- In Drosophila melanogaster white (w) and miniature (m) wings are controlled by X-linked recessive genes with a recombination fruequency between them of approximately 38%. Show the sexes, phenotypes and proportions of offspring expected from the following mating:a. ++/wm female X wm maleb. +m/w+ female X w+ malec. w+/+m female X ++ maleIf we assume that white eyes and miniature wings are not x-linked but are linkedto the autosomal genes, what phenotypic frequencies would you expect from this cross: ++/wm female X ++/wm male?arrow_forwardBlack body (b) and purple eye (pr) are recessive autosomal mutations in Drosophila. Bridges are crossed b/b females with pr/pr males and in the F2 observed 684 wild type, 371 black-bodied, and 300 purple-eyed flies. Do these results indicate that the b and pr genes are closely linked? Explain. (Remember that there is no crossing-over in male Drosophila)..arrow_forwardIn Drosophila, a heterozygous female for the X-linkedrecessive traits a, b, and c was crossed to a male that phenotypically expressed a, b, and c. The offspring occurred inthe following phenotypic ratios.+ b c 460a + + 450a b c 32+ + + 38a + c 11+ b + 9 No other phenotypes were observed.(a) What progeny phenotypes are missing? Why?arrow_forward
- Consider the following crosses in Drosophila. The two traits being investigated involve eye color and the presence or absence of wing crossveins. The outcomes of four crosses are shown below.›arrow_forwardIn Drosophila fruit flies, the genes for warped wings (dwp), rumpled bristles (rmp), and pallid wings (pld) are linked. A trihybrid female for all three allleles is crossed with homozygous recessive male for all three alleles and the offspring obtained showed the following phenotypes: 3 pld rmp dwp 428 pld rmp + 427 + + dwp 48 + rmp + 47 pld + dwp 23 pld + + 2 + + + 22 + rmp dwp What is the order and map distance between these three alleles?arrow_forwardA maternal effect gene in Drosophila, called torso, occurs as a functionalallele (torso+) and a nonfunctional, recessive allele (torso−)that prevents the correct development of anterior- and posterior-moststructures. A wild-type male (torso+torso+) is crossed to a female ofunknown genotype. This cross produces offspring (larva) that are allmissing their anterior- and posterior-most structures and therefore die during early development. What are the genotype and the phenotypeof the female fly in this cross? What are the genotypes andphenotypes of the female fly’s parents?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning
![Text book image](https://www.bartleby.com/isbn_cover_images/9781305251052/9781305251052_smallCoverImage.gif)