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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Chapter 13, Problem 25P
Duchenne muscular dystrophy (DMD) is caused by a recessive mutant allele of an X-linked gene called dystrophin. Rarely, females have disease symptoms as severe as those in males hemizygous for the recessive allele. These females are heterozygous for X-autosome reciprocal translocations where the X chromosome breakage occurred in the middle of the dystrophin gene, breaking it into two pieces.
| a. | If it is equally likely for X chromosome inactivation to spread from either of the X chromosome inactivation centers (XICs; see Fig. 12.15) in the cells of this patient, what proportion of her cells would you expect to have normal function of the dystrophin gene? |
| b. | Is it possible that some autosomal genes might be inactivated in some cells of this woman? Is it possible that some X-linked genes that are normally subject to X inactivation might be expressed from both X chromosomes in this woman? To answer these questions, draw a figure showing the normal and translocated chromosomes involved, and the locations of: centromeres, potentially inactivated autosomal genes, X chromosome genes potentially no longer subject to X inactivation, the dystrophin gene, and the XICs. Assume for simplicity that dystrophin and the XIC are located in the middle of the short and long arms of the X chromosome, respectively. |
| c. | It is found that virtually none of the cells in this woman expresses any of the dystrophin gene product. Use your answers to parts (a) and (b) to explain this interesting observation. Consider what changes in gene expression might do to the survival and proliferation of cells. |
| d. | Discuss how scientists might have used X:autosome reciprocal translocations to help map the XIC on the human X chromosome. Why does your answer to part (c) illustrate a potential pitfall of this approach? |
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Chapter 13 Solutions
Genetics: From Genes to Genomes
Ch. 13 - For each of the terms in the left column, choose...Ch. 13 - Prob. 2PCh. 13 - For each of the following types of chromosomal...Ch. 13 - For the following types of chromosomal...Ch. 13 - One of the X chromosomes in a particular...Ch. 13 - A diploid strain of yeast was made by mating a...Ch. 13 - The two graphs that follow represent genomic...Ch. 13 - A series of chromosomal mutations in Drosophila...Ch. 13 - Indicate which of the four major classes of...Ch. 13 - The recessive, X-linked z1 mutation of the...
Ch. 13 - Genes a and b are 21 m.u. apart when mapped in...Ch. 13 - In the following group of figures, the pink lines...Ch. 13 - Three strains of Drosophila Bravo, X-ray, and...Ch. 13 - Two yeast strains were mated and sporulated...Ch. 13 - Suppose a haploid yeast strain carrying two...Ch. 13 - In the mating between two haploid yeast strains...Ch. 13 - During ascus formation in Neurospora, any...Ch. 13 - In the following figure, black and pink lines...Ch. 13 - In Drosophila, the gene for cinnabar eye color is...Ch. 13 - Semisterility in corn, as seen by unfilled ears...Ch. 13 - A promising biological method for insect control...Ch. 13 - Prob. 23PCh. 13 - a. Among the progeny of a self-fertilized...Ch. 13 - Duchenne muscular dystrophy DMD is caused by a...Ch. 13 - WHIM syndrome is a disease of the immune system...Ch. 13 - Explain how transposable elements can cause the...Ch. 13 - The Drosophila genome normally harbors about 40 P...Ch. 13 - Drosophila P elements were discovered because of a...Ch. 13 - Flies homozygous for mutant alleles of a...Ch. 13 - Fred and Mary have a child named Bob. The genomic...Ch. 13 - Uniparental disomy is a rare phenomenon in which...Ch. 13 - Among adults with Turner syndrome, it has been...Ch. 13 - In Neurospora, his2 mutants require the amino acid...Ch. 13 - Human geneticists interested in the effects of...Ch. 13 - The incidence of Down syndrome will be very high...Ch. 13 - The Drosophila chromosome 4 is extremely small;...Ch. 13 - Down syndrome is usually caused by having a...Ch. 13 - Common red clover, Trifolium pratense, is a...Ch. 13 - The numbers of chromosomes in the somatic cells of...Ch. 13 - Prob. 41PCh. 13 - Somatic cells in organisms of a particular diploid...Ch. 13 - An allotetraploid species has a genome composed of...Ch. 13 - Prob. 44PCh. 13 - Chromosomes normally associate during meiosis I as...Ch. 13 - Using whole-genome sequencing, how could you...Ch. 13 - Prob. 47PCh. 13 - Prob. 48PCh. 13 - Seedless watermelons that you find in the...Ch. 13 - The names of hybrid animals are usually themselves...Ch. 13 - While most animals cannot tolerate polyploidy,...Ch. 13 - What characteristic property of translocations...Ch. 13 - Prob. 53PCh. 13 - In the accompanying figure, the top and bottom...Ch. 13 - Prob. 55PCh. 13 - The accompanying figure shows idiograms of human...Ch. 13 - Prob. 57P
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