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c. Explain how this phenomenon relates to hybrid dysgenesis, described in Problem 29 of Chapter 13.

c. Explain how this phenomenon relates to hybrid dysgenesis, described in Problem 29 of Chapter 13.

Human Heredity: Principles and Issues (MindTap Course List)
Human Heredity: Principles and Issues (MindTap Course List)
11th Edition
ISBN:9781305251052
Author:Michael Cummings
Publisher:Michael Cummings
Chapter7: Development And Sex Determination
Section: Chapter Questions
Problem 19QP: Equalizing the Expression of X Chromosome Genes in Males and Females Individuals with an XXY...
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c. Explain how this phenomenon relates to hybrid
dysgenesis, described in Problem 29 of Chapter 13.

Acrobat Reader File Edit View Sign Window Help Mon May 3 1:21 A Genetics.pdf Home Tools Genetics.pdf Sign In 481 (502 of 849) 109% At least one signature is invalid. Signature Panel Problems 481 observation that dysgenic progeny result only from crosses of laboratory females with outside males, and not vice versa. Explain this hypothesis. Why Section 13.3 2. Explain how transposable elements can cause the movement of genes that are not part of the transpos- a le element. do the P elements mobilize when the cross occurs in one direction but not the other? (You will see in Chapter 17 that this hypothesis is correct, but it accounts for only part of the story.) c. When males from certain outside strains are mated to lab females, the hybrid progeny are only partially sterile rather than completely sterile. Given this information, describe crosses that would allow you to isolate loss-of-function muta- tions in the X-linked Drosophila gene yellow that are caused by P element insertion. (These reces- sive mutant alleles will produce yellow rather than the wild-type tan body color.) At the molec- ular level, what do you think explains the differ- ence between outside strains whose hybrid progeny are all sterile and outside strains whose progeny are only semisterile? d. In wild-type fruit flies, researchers can observe rare patches on the bodies that have yellow rather than tan color. Interestingly, the frequency of these yellow patches did not increase in the prog- eny of a cross between outside males and lab females. What property of hybrid dysgenesis does this result suggest? 28. The Drosophila genome normally harbors about 40 P elements. Some of these DNA transposons are auton- omous and some of which are nonautonomous. Review the structure of a P element (Fig. 13.27). a. Suppose one of the P elements suffered a deletion of one of its inverted repeats. Would this mutation affect the ability of the P element to move? Would it affect the ability of other P elements to move? b. Suppose one of the autonomous P elements suf- fered a mutation in the splice acceptor site for the intron drawn in yellow color in Fig. 13.27, so that now this intron cannot be spliced out of the primary transcript. Would this mutation affect the ability of the P element to move? Would it also affect other P elements? c. Answer part (b) again, assuming that the Pelement in question was the only autonomous P element in the genome. d. As illustrated in Fig. 13.27, P elements are not nor- mally mobile in somatic cells. Describe a mutant P element that could mobilize in somatic cells. Would the mutation also affect the ability of other P elements to mobilize in the same somatic cells? 30. Flies homozygous for mutant alleles of a Drosophila MAY
Transcribed Image Text:Acrobat Reader File Edit View Sign Window Help Mon May 3 1:21 A Genetics.pdf Home Tools Genetics.pdf Sign In 481 (502 of 849) 109% At least one signature is invalid. Signature Panel Problems 481 observation that dysgenic progeny result only from crosses of laboratory females with outside males, and not vice versa. Explain this hypothesis. Why Section 13.3 2. Explain how transposable elements can cause the movement of genes that are not part of the transpos- a le element. do the P elements mobilize when the cross occurs in one direction but not the other? (You will see in Chapter 17 that this hypothesis is correct, but it accounts for only part of the story.) c. When males from certain outside strains are mated to lab females, the hybrid progeny are only partially sterile rather than completely sterile. Given this information, describe crosses that would allow you to isolate loss-of-function muta- tions in the X-linked Drosophila gene yellow that are caused by P element insertion. (These reces- sive mutant alleles will produce yellow rather than the wild-type tan body color.) At the molec- ular level, what do you think explains the differ- ence between outside strains whose hybrid progeny are all sterile and outside strains whose progeny are only semisterile? d. In wild-type fruit flies, researchers can observe rare patches on the bodies that have yellow rather than tan color. Interestingly, the frequency of these yellow patches did not increase in the prog- eny of a cross between outside males and lab females. What property of hybrid dysgenesis does this result suggest? 28. The Drosophila genome normally harbors about 40 P elements. Some of these DNA transposons are auton- omous and some of which are nonautonomous. Review the structure of a P element (Fig. 13.27). a. Suppose one of the P elements suffered a deletion of one of its inverted repeats. Would this mutation affect the ability of the P element to move? Would it affect the ability of other P elements to move? b. Suppose one of the autonomous P elements suf- fered a mutation in the splice acceptor site for the intron drawn in yellow color in Fig. 13.27, so that now this intron cannot be spliced out of the primary transcript. Would this mutation affect the ability of the P element to move? Would it also affect other P elements? c. Answer part (b) again, assuming that the Pelement in question was the only autonomous P element in the genome. d. As illustrated in Fig. 13.27, P elements are not nor- mally mobile in somatic cells. Describe a mutant P element that could mobilize in somatic cells. Would the mutation also affect the ability of other P elements to mobilize in the same somatic cells? 30. Flies homozygous for mutant alleles of a Drosophila MAY
Acrobat Reader File Edit View Sign Window Help Mon May 3 1:21 A Genetics.pdf Home Tools Genetics.pdf Sign In 481 (502 of 849) 125% At least one signature is invalid. Signature Panel gene called rough have slightly malformed (rough eyes, instead of normal smooth eyes. Two differen strains of flies exist, each with a different P eleme induced mutant rough allele. In each strain, the P ment in the rough gene is the only P element in th fly genome. Bookmarks 29. Drosophila P elements were discovered because of a phenomenon called hybrid dysgenesis-sterility of particular hybrid progeny. When scientists in the 1970s crossed their D. melanogaster laboratory strains to flies of the same species obtained from natural environments outside the lab, they observed a remarkable result: The progeny of the crosses were sterile, but only when outside males were crossed with lab strain females. Progeny resulting from crosses of outside females with lab males W 13.5 Variation in Number of Chromosome a. When homozygotes for one of the rough mutai alleles were bred for several generations, in ea generation flies appeared either with wild-type or with much more severely rough eyes. Pure-bre wild-type or severely rough-eyed lines could b generated from these unusual flies. Explain. Sets: Euploidy W 13.6 Genome Restructuring and Evolution were perfectly normal. DNA analysis revealed that while the genomes of the outside flies contain P elements, the lab fly genomes have none. Apparently, P elements spread throughout the wild population of D. melanogaster after the capture of the originators of present-day laboratory strains over 100 years ago. W Fast Forward: Programmed DNA Rearrangements b. When homozygotes for the other rough mutant allele were grown for many generations, neithe wild-type flies nor flies with more severely rou eyes were ever seen. Explain. and the Immune System v A chapter 14 Bacterial Genetics A 14.1 The Section 13.4 a. The hybrid progeny are sterile because their germ- line cells have a high rate of mutation and chromo- somal rearrangement (dysgenesis) caused by high rates of P element mobilization. Explain how P element movement can cause dysgenesis. Enormous 31. Fred and Mary have a child named Bob. The gen DNAS of these three individuals are used as probe ASO microarrays such as that shown in Fig. 11.1 The results with 10 SNP loci (1–10) located alon chromosome 21 are shown in the figure that follo Yellow, orange, and red indicate increasing intens of hybridization. Diversity of Bacteria A 14.2 Bacterial Genomes b. Scientists first hypothesized that the deposition of P element-encoded repressor protein (see Fig. 13.27) in egg cytoplasm is behind the O 14.3 Bacteria as Experimental Organisms O 14.4 Gene Transfer |+ in Racteria 8.50 x 10.88 in MAY 3 w
Transcribed Image Text:Acrobat Reader File Edit View Sign Window Help Mon May 3 1:21 A Genetics.pdf Home Tools Genetics.pdf Sign In 481 (502 of 849) 125% At least one signature is invalid. Signature Panel gene called rough have slightly malformed (rough eyes, instead of normal smooth eyes. Two differen strains of flies exist, each with a different P eleme induced mutant rough allele. In each strain, the P ment in the rough gene is the only P element in th fly genome. Bookmarks 29. Drosophila P elements were discovered because of a phenomenon called hybrid dysgenesis-sterility of particular hybrid progeny. When scientists in the 1970s crossed their D. melanogaster laboratory strains to flies of the same species obtained from natural environments outside the lab, they observed a remarkable result: The progeny of the crosses were sterile, but only when outside males were crossed with lab strain females. Progeny resulting from crosses of outside females with lab males W 13.5 Variation in Number of Chromosome a. When homozygotes for one of the rough mutai alleles were bred for several generations, in ea generation flies appeared either with wild-type or with much more severely rough eyes. Pure-bre wild-type or severely rough-eyed lines could b generated from these unusual flies. Explain. Sets: Euploidy W 13.6 Genome Restructuring and Evolution were perfectly normal. DNA analysis revealed that while the genomes of the outside flies contain P elements, the lab fly genomes have none. Apparently, P elements spread throughout the wild population of D. melanogaster after the capture of the originators of present-day laboratory strains over 100 years ago. W Fast Forward: Programmed DNA Rearrangements b. When homozygotes for the other rough mutant allele were grown for many generations, neithe wild-type flies nor flies with more severely rou eyes were ever seen. Explain. and the Immune System v A chapter 14 Bacterial Genetics A 14.1 The Section 13.4 a. The hybrid progeny are sterile because their germ- line cells have a high rate of mutation and chromo- somal rearrangement (dysgenesis) caused by high rates of P element mobilization. Explain how P element movement can cause dysgenesis. Enormous 31. Fred and Mary have a child named Bob. The gen DNAS of these three individuals are used as probe ASO microarrays such as that shown in Fig. 11.1 The results with 10 SNP loci (1–10) located alon chromosome 21 are shown in the figure that follo Yellow, orange, and red indicate increasing intens of hybridization. Diversity of Bacteria A 14.2 Bacterial Genomes b. Scientists first hypothesized that the deposition of P element-encoded repressor protein (see Fig. 13.27) in egg cytoplasm is behind the O 14.3 Bacteria as Experimental Organisms O 14.4 Gene Transfer |+ in Racteria 8.50 x 10.88 in MAY 3 w
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