Concept explainers
A male and a female mouse are each from pure-breeding albino strains. They have a litter of
a. Using clearly defined allele symbols of your own c hoosing, give the genotypes of parental and
b. What genetic phenomenon explains the
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Genetic Analysis: An Integrated Approach (3rd Edition)
- In an autotetraploid Chinese primrose (Primula sinensis), the gene controlling stigma color is very near the centromere of the chromosome carrying it. The allele G for green stigma is dominant to g for red stigmas. A homozygous green autotetraploid strain is crossed with a homozygous red autotetraploid strain. a. What phenotypic ratio of green to red is expected if: The F1’s are intercrossed? The F1’s are crossed with red plantsarrow_forwardMultiple crosses were made between true-breeding lines of black and yellow Labrador retrievers. All the F1 progeny were yellow. When these progeny were intercrossed, they produced an F2 consisting of 121 yellow, 9 black and 30 chocolate. What epistatic ratio and what kind of epistasis is approximated in the F2? Propose a biochemical pathway for coat color in Labrador retrievers based on the type of epistasis. Correlate each genotype with the phenotype that would occur in your pathway. Also show the frequency of each genotype. A-B- A-bb aaB- aabbarrow_forwardMost flour beetles are black, but several color variants are known. Crosses of pure-breeding parents produced the following results (see table) in the F1 generation, and intercrossing the F1 from each cross gave the ratios shown for the F2 generation. The phenotypes are abbreviated Bl, black; Br, brown; Y, yellow; and W, white. a. From these results, deduce and explain the inheritance of these colors. b. Write the genotypes of each of the parents, the F1, and the F2 in all crosses.arrow_forward
- A Neurospora cross was made between a strain that carried the mating-type allele A and the mutant allele arg-1and another strain that carried the mating-type allele aand the wild-type allele for arg-1 (+). Four hundred linear octads were isolated, and they fell into the sevenclasses given in the table below. (For simplicity, they areshown as tetrads.)a. Deduce the linkage arrangement of the mating-typelocus and the arg-1 locus. Include the centromere orcentromeres on any map that you draw. Label all intervalsin map units.b. Diagram the meiotic divisions that led to class 6. Labelclearlyarrow_forwardE. W. Lindstrom crossed two corn plants with green seedlings and obtained the following progeny: 3583 green seedlings, 853 virescentwhite seedlings, and 260 yellow seedlings (E. W. Lindstrom. 1921. Genetics 6:91–110). a. Give the genotypes for the green, virescent-white, and yellow progeny. b. Explain how color is determined in these seedlings. c. Is there epistasis among the genes that determine color in the corn seedlings? If so, which gene is epistatic and which is hypostatic?arrow_forwardThe normal color of snapdragons is red. Some pure lines showing the variations of flower color have been found. When these lines were crossed, they gave the results attached. A. From the data given, determine if alleles of one, two, or three genes are generating these traits and why? B. Define the results of cross #5 with gene symbols and a complete explanation of ratios and any relevant genetic terms.arrow_forward
- Three genes in fruit flies affect a particular trait, and at least one dominant allele of each gene is necessary to get a wild-type phenotype. a. What phenotypic ratio would you predict among the progeny if you crossed triply heterozygous flies? b. You cross a particular wild-type male in succession with three tester strains. In the cross with one tester strain (AA bb cc), only 1/4 of the progeny are wild type. In the crosses involving the other two tester strains (aa BB cc and aa bb CC), half of the progeny are wild type. What is the genotype of the wild-type male? (Pls help asap!!)arrow_forward. a. A mouse cross A/a ⋅ B/b × a/a ⋅ b/b is made, and inthe progeny there are25% A/a ⋅ B/b, 25% a/a ⋅ b/b,25% A/a ⋅ b/b, 25% a/a ⋅ B/bExplain these proportions with the aid of simplifiedmeiosis diagrams.b. A mouse cross C/c ⋅ D/d × c/c ⋅ d/d is made, and inthe progeny there are45% C/c ⋅ d/d, 45% c/c ⋅ D/d,5% c/c ⋅ d/d, 5% C/c ⋅ D/dExplain these proportions with the aid of simplifiedmeiosis diagrams.arrow_forwardWild-type mice have brown fur and short tails. Loss of function of a particular gene produces white fur, while loss of function of another gene produces long tails, and loss of function at a third locus produces agitated behavior. Each of these loss of function alleles is recessive. If a wild-type mouse is crossed with a triple mutant, and their F1 progeny is test-crossed, the following recombination frequencies are observed among their progeny. Produce a genetic map for these loci. Brown, short tailed, normal: 955 White, short tailed, normal: 16 Brown, short tailed, agitated: 0 White, short tailed, agitated: 36 Brown, long tailed, normal: White, long tailed, normal: Brown, long tailed, agitated: 46 0 14 White, long tailed, agitated: 933arrow_forward
- In roses, purple flower color is determined by the dominant P allele, while pphomozygotes are white. The presence of long stems is determined by the dominant S allele, while ss homozygotes have short stems. Both mutations are completely penetrant. A test cross was performed between a rose plant of unknown genotype with a white flowered, short stemmed rose plant (pp ss) and the following 200 progeny plants were obtained: 84 white flowers, long stems 16 purple flowers, long stems 82 purple flowers, short stems 18 white flowers, short stems Select two statements below that are TRUE. options: The P and S genes independently assort during meiosis. The map distance between P and S is 17 cM. The genotype of the progeny plants with purple flowers and short stems is PP ss. The map distance between P and S is 83 cM. The homologs in the plant with…arrow_forwardA test cross between a plant of genotype PpSs and the tester white plant with wrinkled seed coat (ppss) gives the following numbers of progeny in four phenotypic types. 14:87:83:16 (purple flower + smooth seed coat: purple flower + wrinkled seed coat: white flower + smooth seed coat: white flower + wrinkled seed coat). a. What is the expected ratio of progeny phenotypes assuming independent assortment of alleles? b. Explain how ratios of progeny show that the two genes are linked. c. How many map units separate the purple and smooth genes? Show your calculations. d. What is the “parental” genotype of the heterozygous parent? (i.e. Which alleles of the P and S loci are present on each of the two chromosomes of the doubly heterozygous parent of this test cross?)arrow_forwardIn an autotetraploid Chinese primrose (Primula sinensis L.), the gene controlling stigma color is very near the centromere of the chromosome carrying it. The allele G for green stigma is dominant to g for red stigmas. A homozygous green autotetraploid strain is crossed with a homozygous red autotetraploid strain. Show all solutions and label solutions and final answers properly. a. What is the genotype of the F1? b. Derive the types of gametes the F1’s may be expected to form and the proportion of each. c. What are the expected genotypic ratio, and phenotypic ratio of green to red if: i. the F1’s are intercrossed? ii. the F1’s are crossed with red plants? d. If the G locus were 50 or more map units from the centromere, what types and proportions of gametes would the F1 be expected to produce? Derive the expected F2 genotypic and phenotypic ratios Answer letter D only. please, thank you!arrow_forward
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