Genetics: From Genes to Genomes, 5th edition
5th Edition
ISBN: 9780073525310
Author: Leland H. Hartwell, Michael L. Goldberg, Janice A. Fischer, Leroy Hood, Charles F. Aquadro
Publisher: McGraw-Hill Education
expand_more
expand_more
format_list_bulleted
Textbook Question
Chapter 16, Problem 30P
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? |
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
Human females who are heterozygous for an X-linked recessive allele sometimes exhibit mild expression of the trait. However, such mild expression of X-linked traits in females who are heterozygous for Xlinked alleles is not seen in Drosophila. What might cause this difference in the expression of X-linked genes between human females and female Drosophila? (Hint: In Drosophila, dosage compensation is accomplished by doubling the activity of genes on the X chromosome of males.)
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 16 Solutions
Genetics: From Genes to Genomes, 5th edition
Ch. 16 - For each of the terms in the left column, choose...Ch. 16 - Does each of the following types of gene...Ch. 16 - List five events other than transcription...Ch. 16 - Which eukaryotic RNA polymerase RNA pol I, pol II,...Ch. 16 - You have synthesized an enhancerless GFP reporter...Ch. 16 - Prob. 6PCh. 16 - Yeast genes have cis-acting elements upstream of...Ch. 16 - A single UASG regulates the expression of three...Ch. 16 - Prob. 9PCh. 16 - a. Assume that two transcription factors are...
Ch. 16 - a. You want to create a genetic construct that...Ch. 16 - In Problem 12, you identified a genomic region...Ch. 16 - Prob. 13PCh. 16 - Prob. 14PCh. 16 - Genes in both prokaryotes and eukaryotes are...Ch. 16 - Prob. 16PCh. 16 - Prader-Willi syndrome is caused by a mutation in...Ch. 16 - The human IGF-2R gene is autosomal and maternally...Ch. 16 - Follow the expression of a paternally imprinted...Ch. 16 - Reciprocal crosses were performed using two inbred...Ch. 16 - Interestingly, imprinting can be tissue-specific....Ch. 16 - Prob. 22PCh. 16 - a. How can a single eukaryotic gene give rise to...Ch. 16 - A hunchback gene, a gene necessary for proper...Ch. 16 - You know that the mRNA and protein produced by a...Ch. 16 - You are studying a transgenic mouse strain that...Ch. 16 - Prob. 27PCh. 16 - Scientists have exploited the siRNA pathway to...Ch. 16 - Researchers know that Fru-M controls male sexual...Ch. 16 - The Drosophila gene Sex lethal Sxl is deserving of...Ch. 16 - Prob. 31P
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- In drosophila, a recessive mutation (m-) of a maternal effect gene results in an abnormalphenotype wherein homozygous (m-m-) females produce eggs that cannot support embryonicdevelopment. Homozygous (m-m-) males, however, can still produce viable sperm. Using m+ todenote a normal gene, determine the genotypes and phenotypes of the F1s produce by a crossbetween a heterozygous female and a recessive male. From the offspring, backcross the recessivefemale with the paternal strain. What are the genotypes and phenotypes of the F2s?arrow_forwardIn 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. What are the genotypes and phenotypes of the F2s? Show COMPLETE cross for both cases. If m-m- females produce useless eggs, then how are m-m- produced?arrow_forwardIn Drosophila, the X-linked recessive mutation vermilion (v) causes bright red eyes, in contrast to the brick-red eyes of wild type. A separate autosomal recessive mutation, suppressor of vermilion (su-v), causes flies homozygous or hemizygous for v to have wildtype eyes. In the absence of vermilion alleles, su-v has no effect on eye color. Determine the F1 and F2 phenotypic ratios from a cross between a female with wild-type alleles at the vermilion locus, but who is homozygous for su-v, with a vermilion male who has wildtype alleles at the su-v locusarrow_forward
- The locations of six deletions have been mapped to a Drosophila chromosome, as shown in the following deletion map. Recessive mutations a, b, c, d, e, and f are known to be located in the same region as the deletions, but the order of the mutations on the chromosome is not known.arrow_forwardThe locations of six deletions have been mapped to a Drosophila chromosome, as shown in the following deletion map. Recessive mutations a, b, c, d, e, and f are known to be located in the same region as the deletions, but the order of the mutations on the chromosome is not known. (refer image for contination )arrow_forwardA Drosophila embryo dies during early embryogenesis due to arecessive allele of a maternal effect gene called bicoid. The wildtypeallele is designated bicoid +. What are the genotypes and phenotypesof the embryo’s mother and maternal grandparents?arrow_forward
- Suppose a researcher has three different Drosophila strains that have mutations in the bicoid gene called bicoid-A, bicoid-B, and bicoid-C; the wild type is designated bicoid +. To study these mutations, phenotypically normal female flies that are homozygous for the given bicoid mutation were obtained, and their oocytes were analyzed using a Northern blot to determine the size and/or amount of the bicoid mRNA and in situ hybridization to determine the bicoid mRNA location within the oocyte. A wild-type strain was also analyzed as a control. In both cases, the probe was complementary to the bicoid mRNA and the results are shown below. (Anterior is on the left; posterior is on the right.) Northern blot 1 2 - 3 4 In situ hybridization Wild type Lane 1. Wild type (bicoid*) Lane 2. bicoid-A Lane 3. bicoid-B Lane 4. bicoid-C bicoid-B bicoid-A bicoid-C Which mutation is likely to cause the embryo to develop two "anterior" ends? bicoid-B Obicoid-A bicoid-Carrow_forwardImagine a scenario in which prenatal testing of a human female fetus indicates that the baby will have a normal XX karyotype but is heterozygous for a mutation that inactivates the Xist promoter. Allele “Xr” represents the mutated version of the Xist promoter, and “XR” represents the normal version of the Xist promoter. How will this mutation affect the process of X inactivation?A. "X inactivation will still be random with both mutant and normal X chromosomes being randomly inactivated" B. "The chromosome with the mutant Xist promoter will always be active" C. "The chromosome with the mutant Xist promoter will always be inactivated" D. "The normal X chromosome (no mutation in Xist) will always be active" E. "The normal X chromosome (no mutation in Xist) will always be inactivated"arrow_forwardIn Drosophila sex determination (Check all that apply.) A) XY individuals transcribe the Sxl gene early but not late. B XX individuals carry the Sxl gene, XY individuals do not. XX individuals transcribe the Sxl gene, XY individuals do not. XX individuals express the Sxl protein, XY individuals do not. E) The Sxl transcript (Pre-MRNA) is spliced differently in XX compared to XY individuals.arrow_forward
- Duchenne Muscular Dystrophy (DMD) is a disorder that primarily affects the function of skeletal muscles used for movement and cardiac muscles used for heart beating. Dystrophin is a protein encoded by a single gene, DMD, that is expressed in skeletal and cardiac muscle. Some forms of muscular dystrophy may be caused by different mutations in the DNA sequence of the DMD gene. Because the DMD locus is on the X chromosome, males are affected at higher rates. Two brothers, one of whom has DMD and one of whom does not, worked with their genetic counselor (Links to an external site.) to have their DMD gene sequenced to identify genetic variation that may explain why one brother was affected and the other not. Because DMD is a very long gene, a fictionalized, simplified model of the results is presented here (Figure 1). The actual DMD mRNA is about 16,000 base-pairs!------Consider single nucleotide polymorphism (SNP) #1 (Figure 1). Is this mutation likely to cause Duchenne muscular…arrow_forwardA maternal effect gene in Drosophila, called torso, is found as a recessive allele that prevents the correct development of anterior- and posterior-most structures. A wild-type (homozygous) male is crossed to a female of unknown genotype. This mating produces 100% larva that are missing their anterior- and posterior-most structures and therefore die during early development. What is the genotype and phenotype of the female fly in this cross? What are the genotypes and phenotypes of the female fly’s parents? Show COMPLETE cross.arrow_forwardIn humans, dosage compensation is accomplished by: inactivating one X chromosome in female somatic cells inactivating one homolog from each homologous pair of chromosomes in female somatic cells inactivating the Y chromosome in male somatic cells increasing gene expression from the X chromosome in male somatic cellarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning
Human Heredity: Principles and Issues (MindTap Co...
Biology
ISBN:9781305251052
Author:Michael Cummings
Publisher:Cengage Learning
Embryology | Fertilization, Cleavage, Blastulation; Author: Ninja Nerd;https://www.youtube.com/watch?v=8-KF0rnhKTU;License: Standard YouTube License, CC-BY