Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 17, Problem 41P
The Drosophila gene Sex lethal (Sxl) is deserving of its name. Certain alleles have no effect on XY animals but cause XX animals to die early in development. Other alleles have no effect on XX animals but cause XY animals to die early in development. Thus, some Sxl alleles are lethal to females, while others are lethal to males.
a. | Would you expect a null mutation in Sxl to cause lethality in males or in females? What about a constitutively active Sxl mutation? |
b. | Why do Sxl alleles of either type cause lethality in a specific sex? The gene transformer (tra) gets its name from sexual transformation, as some tra alleles can change XX animals into morphological males, while other tra alleles can change XY animals into morphological females. |
c. | Which of these sex transformations would be caused by null alleles of tra and which would be caused by constitutively active alleles of tra? |
d. | In contrast with Sxl, null tra mutations do not cause lethality either in XX or in XY animals. However, the Sxl protein regulates the production of the Tra protein. Why then do all tra mutant animals survive? |
e. | Predict the consequences of null mutations in tra-2 on XX and XY animals. (Recall that tra-2 encodes a protein, expressed in both sexes, that is required for Tra function.) |
f. | XY males carrying loss-of-function mutations in the fruitless (fru) gene display aberrant courtship behavior. Would you predict that either XX or XY animals with wild-type alleles of fru but loss-of-function mutations of tra would also court abnormally? |
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The Drosophila gene Sex lethal (Sxl) is deserving of itsname. Certain alleles have no effect on XY animals butcause XX animals to die early in development. Other alleles have no effect on XX animals but cause XY animals to die early in development. Thus, some Sxl allelesare lethal to females, while others are lethal to males.a. Would you expect a null mutation in Sxl to causelethality in males or in females? b. Why do Sxl alleles of either type cause lethality ina specific sex?The gene transformer (tra) gets its name from sexualtransformation, as some tra alleles can change XXanimals into morphological males, while other traalleles can change XY animals into morphologicalfemales.c. Which of these sex transformations would becaused by null alleles of tra and which would becaused by constitutively active alleles of tra?d. In contrast with Sxl, null tra mutations do notcause lethality either in XX or in XY animals.However, the Sxl protein regulates the productionof the Tra protein. Why…
In drosophila, a recessive mutation (m-) of a maternal effect gene results in an abnormal phenotype wherein homozygous (m-m-) females produce eggs that cannot support embryonic development. Homozygous (m-m-) males, however, can still produce viable sperm.
(A) Using m+ to denote a normal gene, determine the genotypes and phenotypes of the F1s produce by a cross between a heterozygous female and a recessive male.
(B) From the offspring, backcross the recessive female with the paternal strain. What are the genotypes and phenotypes of the F2s?
(C) If m-m- females produce useless eggs, then how are m-m- produced?
In drosophila, a recessive mutation (m-) of a maternal effect gene results in an abnormal phenotype wherein homozygous (m-m-) females produce eggs that cannot support embryonic development. Homozygous (m-m-) males, however, can still produce viable sperm. Using m+ to denote a normal gene, determine the genotypes and phenotypes of the F1s produce by a cross between a heterozygous female and a recessive male. From the offspring, backcross the recessive female with the paternal strain.
1. What are the genotypes and phenotypes of the F2s?
2. If m-m- females produce useless eggs, then how are m-m- produced?
Chapter 17 Solutions
Genetics: From Genes to Genomes
Ch. 17 - For each of the terms in the left column, choose...Ch. 17 - For each of the following types of gene...Ch. 17 - List five events other than transcription...Ch. 17 - Which eukaryotic RNA polymerase RNA pol I, pol II,...Ch. 17 - As shown in the following diagram, a single...Ch. 17 - You have synthesized an enhancerless GFP reporter...Ch. 17 - Prob. 7PCh. 17 - Prob. 8PCh. 17 - A single UAS regulates the expression of three...Ch. 17 - MyoD is a transcriptional activator that turns on...
Ch. 17 - a. Assume that two transcription factors are...Ch. 17 - Prob. 12PCh. 17 - In Problem 12, you identified a genomic region...Ch. 17 - Prob. 14PCh. 17 - Prob. 15PCh. 17 - Genes in both prokaryotes and eukaryotes are...Ch. 17 - Prob. 17PCh. 17 - Lysine 4 of histone H3 H3K4 is methylated in the...Ch. 17 - J.T. Lis and collaborators have developed an...Ch. 17 - Hydatiform moles are growths of undifferentiated...Ch. 17 - Prader-Willi syndrome is caused by a mutation in...Ch. 17 - The human IGF2 gene is autosomal and maternally...Ch. 17 - Follow the expression of a paternally imprinted...Ch. 17 - Reciprocal crosses were performed using two inbred...Ch. 17 - Interestingly, imprinting can be tissue-specific....Ch. 17 - Prob. 26PCh. 17 - A method for detecting methylated CpGs involves...Ch. 17 - Honeybees Apis mellifera provide a striking...Ch. 17 - Consider the experiment in Fig. 17.24, where the...Ch. 17 - A protein or RNA that regulates gene expression in...Ch. 17 - a. How can a single eukaryotic gene give rise to...Ch. 17 - A hunchback gene, a gene necessary for proper...Ch. 17 - You know that the mRNA and protein produced by a...Ch. 17 - You are studying a transgenic mouse strain that...Ch. 17 - Prob. 35PCh. 17 - Scientists have exploited the siRNA pathway to...Ch. 17 - Persimmons Diospyros lotus are dioecious plants,...Ch. 17 - Drosophila females homozygous for loss-of-function...Ch. 17 - The text has discussed the RNA-Seq technique,...Ch. 17 - Researchers know that Fru-M controls male sexual...Ch. 17 - The Drosophila gene Sex lethal Sxl is deserving of...Ch. 17 - Figure 17.29 shows that the Sxl protein binds to...
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