Wild-type mice have brown fur and short tails. Loss of function of a particular geneproduces white fur, while loss of function of another gene produces long tails, and lossof function at a third locus produces agitated behavior. Each of these loss of functionalleles is recessive. If a wild-type mouse is crossed with a triple mutant, and their F1progeny is test-crossed, the following recombination frequencies are observed amongtheir progeny. Produce a genetic map for these loci.Brown, short tailed, normal: 955White, short tailed, normal:16Brown, short tailed, agitated: 0White, short tailed, agitated: 36Brown, long tailed, normal:White, long tailed, normal:Brown, long tailed, agitated:46014White, long tailed, agitated: 933

The recombination frequency is calculated as the number of recombinant progeny divided by the total…

Answered: Wild-type mice have brown fur and short…

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter15: Genomes And Genomics

Section: Chapter Questions

Problem 2QP: Hemophilia and color blindness are both recessive conditions caused by genes on the X chromosome. To...

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. In a particular kind of ornamental flower, the wildtype flower color is deep purple, and the plants aretrue-breeding. In one true-breeding mutant stock, theflowers have a reduced pigmentation, resulting in alavender color. In a different true-breeding mutantstock, the flowers have no pigmentation and are thuswhite. When a lavender-flowered plant from the firstmutant stock was crossed to a white-flowered plantfrom the second mutant stock, all the F1 plants hadpurple flowers. The F1 plants were then allowed toself-fertilize to produce an F2 generation. The 277 F2plants were 157 purple : 71 white : 49 lavender. a. Explain how flower color is inherited. Is this traitcontrolled by the alleles of a single gene?b. What kinds of progeny would be produced if lavender F2 plants were allowed to self-fertilize?
When true-breeding mice with brown fur and short tails (BBtt)were crossed to true-breeding mice with white fur and long tails(bbTT), all of the F1 offspring had brown fur and long tails. TheF1 offspring were crossed to mice with white fur and short tails.What are the possible phenotypes of the F2 offspring? Which F2offspring are recombinant, and which are nonrecombinant? Whatare the ratios of phenotypes of the F2 offspring if independentassortment is taking place? How are the ratios affected by linkage?
When Calvin Bridges observed a large number of offspring from a cross of white-eyed female Drosophila tored-eyed males, he found very rare white-eyed femalesand red-eyed males among the offspring. He was ableto show that these exceptions resulted from nondisjunction, such that the white-eyed females had received twoXs from the egg and a Y from the sperm, while thered-eyed males had received no sex chromosome fromthe egg and an X from the sperm. What progeny wouldhave arisen from these same kinds of nondisjunctionalevents if they had occurred in the male parent? Whatwould their eye colors have been?
. If you intercrossed F1 heterozygotes of the formA b / a B in mice, the phenotypic ratio among the F2progeny would vary with the map distance betweenthe two genes. Is there a simple way to estimate themap distance based on the frequencies of the F2phenotypes, assuming rates of recombination areequal in males and females? Could you estimatemap distances in the same way if the mouse F1heterozygotes were A B / a b?
Two recessive traits in mice—droopy ears and flaky tail—arecaused by genes that are located 6 mu apart on the same chromosome.A true-breeding mouse with normal ears (De) and a flaky tail ( ft)was crossed to a true-breeding mouse with droopy ears (de) and anormal tail (Ft). The F1 offspring were then crossed to mice withdroopy ears and flaky tails. If this testcross produced 100 offspring,what is the expected outcome of phenotypes?
In Drosophila, a cross was made between a yellowbodied male with vestigial (not fully developed)wings and a wild-type female (brown body). The F1generation consisted of wild-type males and wild-typefemales. F1 males and females were crossed, and theF2 progeny consisted of 16 yellow-bodied males withvestigial wings, 48 yellow-bodied males with normalwings, 15 males with brown bodies and vestigialwings, 49 wild-type males, 31 brown-bodied femaleswith vestigial wings, and 97 wild-type females.Explain the inheritance of the two genes in questionbased on these results.
Summer squash exist in long, spherical, or disk shapes. When atrue-breeding long-shaped strain was crossed to a true-breedingdisk-shaped strain, all of the F1 offspring were disk-shaped. Whenthe F1 offspring were allowed to self-fertilize, the F2 generationconsisted of a ratio of 9 disk-shaped to 6 round-shaped to 1 longshaped. Assuming the shape of summer squash is governed by twodifferent genes, with each gene existing in two alleles, propose amechanism to account for this 9:6:1 ratio
The A locus and the D locus are so tightly linked that norecombination is ever observed between them. If Ad/Ad is crossed with aD/aD and the F1 is intercrossed,what phenotypes will be seen in the F2 and in whatproportions?
. In 1919, Calvin Bridges began studying an X-linkedrecessive mutation causing eosin-colored eyes inDrosophila. Within an otherwise true-breedingculture of eosin-eyed flies, he noticed rare variantsthat had much lighter cream-colored eyes. By intercrossing these variants, he was able to make a truebreeding cream-eyed stock. Bridges now crossedmales from this cream-eyed stock with true-breedingwild-type females. All the F1 progeny had red (wildtype) eyes. When F1 flies were intercrossed, the F2progeny were 104 females with red eyes, 52 maleswith red eyes, 44 males with eosin eyes, and14 males with cream eyes. Assume that thesenumbers represent an 8:4:3:1 ratio.a. Formulate a hypothesis to explain the F1 and F2results, assigning phenotypes to all possiblegenotypes.b. What do you predict in the F1 and F2 generations if the parental cross is between truebreeding eosin-eyed males and true-breedingcream-eyed females?c. What do you predict in the F1 and F2 generationsif the parental cross is…
The mutant FMR-1 allele that causes fragile X syndrome is considered to be X-linked dominant withincomplete penetrance and variable expressivity.Why do most females heterozygous for one mutantand one normal allele have at least some symptomsof the disease?
. The production of pigment in the outer layer of seedsof corn requires each of the three independently assorting genes A, C, and R to be represented by at leastone dominant allele, as specified in Problem 64. Thedominant allele Pr of a fourth independently assortinggene is required to convert the biochemical precursorinto a purple pigment, and its recessive allele pr makesthe pigment red. Plants that do not produce pigmenthave yellow seeds. Consider a cross of a strain of genotype A/A ; C/C ; R/R ; pr/pr with a strain of genotypea/a ; c/c ; r/r ; Pr/Pr.a. What are the phenotypes of the parents?b. What will be the phenotype of the F1?c. What phenotypes, and in what proportions, willappear in the progeny of a selfed F1?d. What progeny proportions do you predict from thetestcross of an F1?
Two recessive traits in mice—droopy ears and flaky tail—arecaused by genes that are located 6 mu apart on the same chromosome.A true-breeding mouse with normal ears (De) and a flaky tail ( ft)was crossed to a true-breeding mouse with droopy ears (de) and anormal tail (Ft). The F1 offspring were then crossed to mice withdroopy ears and flaky tails. If this testcross produced 100 offspring,Make a drawing. Predict the outcome. Make a calculation.

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