Essentials of Genetics (9th Edition) - Standalone book
9th Edition
ISBN: 9780134047799
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 14, Problem 29PDQ
Two related forms of muscular dystrophy–Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)–are both recessive, X-linked, single-gene conditions caused by point mutations, deletions, and insertion in the dystrophin gene. Each mutated form of dystrophin is one allele. Of the two diseases, DMD is much more severe. Given your knowledge of mutations, the genetic code, and translation, propose an explanation for why the two disorders differ greatly in severity.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Two related forms of muscular dystrophy—Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)—are both recessive, X-linked, single-gene conditions caused by point mutations, deletions, and insertion in the dystrophin gene. Each mutated form of dystrophin is one allele. Of the two diseases, DMD is much more severe. Given your knowledge of mutations, the genetic code, and translation, propose an explanation for why the two disorders differ greatly in severity.
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…
What is the underlying genetic defect that causes xeroderma pigmentosum?How can the symptoms of this disease be explained by the genetic defect?
Chapter 14 Solutions
Essentials of Genetics (9th Edition) - Standalone book
Ch. 14 - CASE STUDY| Genetic dwarfism Seven months...Ch. 14 -
CASE STUDY | Genetic dwarfism
Seven months...Ch. 14 -
CASE STUDY| Genetic dwarfism
Seven months...Ch. 14 - CASE STUDY | Genetic dwarfism Seven months...Ch. 14 -
HOW DO WE KNOW?
1. In this chapter, we focused on...Ch. 14 - Review the Chapter Concepts list on page 257....Ch. 14 - What is a spontaneous mutation, and why are...Ch. 14 -
4. Why would a mutation in a somatic cell of a...Ch. 14 - Why is a random mutation more likely to be...Ch. 14 - Most mutations in a diploid organism are...
Ch. 14 - What is meant by a conditional mutation?Ch. 14 -
8. Describe a tautomeric shift and how it may...Ch. 14 - Contrast and compare the mutagenic effects of...Ch. 14 - Why are frameshift mutations likely to be more...Ch. 14 - Why are X rays more potent mutagens than UV...Ch. 14 -
12. DNA damage brought on by a variety of natural...Ch. 14 - Contrast the various types of DNA repair...Ch. 14 -
14. Mammography is an accurate screening...Ch. 14 - Describe how the Ames test screens for potential...Ch. 14 - What genetic defects result in the disorder...Ch. 14 - In a bacterial culture in which all cells are...Ch. 14 - Human equivalents of bacterial DNA mismatch repair...Ch. 14 - A number of different types of mutations in the...Ch. 14 -
20. Some mutations that lead to diseases such as...Ch. 14 - In maize, a Ds or Ac transposon can cause...Ch. 14 -
22. Presented here are hypothetical findings from...Ch. 14 -
23. Cystic fibrosis (CF) is a severe autosomal...Ch. 14 -
24. Electrophilic oxidants are known to create...Ch. 14 - Skin cancer carries a lifetime risk nearly equal...Ch. 14 -
26. The initial discovery of IS elements in...Ch. 14 -
27. It is estimated that about 0.2 percent of...Ch. 14 -
28. It has been noted that most transposons in...Ch. 14 - Two related forms of muscular dystrophy–Duchenne...
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
- Leber Congenital Amaurosis (LCA) causes progressive vision loss due to defects in the gene that encodes RPE65 isomerase. Affected individuals are homozygous recessive for mutant alleles of the RPE65 gene. You are trying to determine the molecular nature of the mutations in three individuals with LCA. For ease of analysis, you may assume that each individual is homozygous for the same mutant allele (though the three individuals have different mutations than each other). You use the polymerase chain reaction to amplify DNA from each patient and you determine the sequence of the DNA and compare it to unaffected individuals. You identify the following differences. Note that the non-template strand of DNA is given and the changes are highlighted using red boldface. You can assume that the sequences are in the first reading frame (eg. the first three nucleotides of each sequence is a codon). The coding region of the gene is 1602 bp and the position of the sequences shown below is…arrow_forwardIn McCune-Albright syndrome, fibrous connective tissue replaces bone, tan patches (café-au-lait spots) dot the skin, and hormone abnormalities cause early puberty and malfunction of the thyroid, pituitary, and adrenal glands. The phenotype is highly variable, and all patients are somatic mosaics for the mutation, which is in the gene GNAS1. Why is the condition seen only in mosaics?arrow_forwardLeber congenital amaurosis (LCA) is a form of congenital blindness in humans and is known to be caused by homozygosity for recessive mutations in the RPE65 gene. Recently, a rare dominant mutation in RPE65 has been implicated as one cause of an eye disease called retinitis pigmentosa, which is characterized by retinal degeneration that can progress to blindness. The dominant RPE65 mutation is a missense mutation causing amino acid 447 in the polypeptide to change from Asp to Glu. Little is known about the nature of the mutant protein. a. Do you think that the dominant allele is more likely a loss-of-function or a gain-of-function mutation? Explain. b. Recently a group of clinicians and scientists reported that gene therapy (gene replacement therapy) for LCA has been at least partially successful. Do you think that the same kind of gene therapy can be used for patients with retinitis pigmentosa caused by the dominant mutant allele of RPE65? Explain.arrow_forward
- Achondroplasia is an autosomal dominant disorder characterized by disproportionate short stature: the legs and arms of people with achondroplasia are short compared with the head and trunk. The disorder is due to a base substitution in the gene, located on the short arm of chromosome 4, that encodes fibroblast growth factor receptor 3 (FGFR3). Although achondroplasia is clearly inherited as an autosomal dominant trait, more than 80% of the people who have achondroplasia are born to parents with normal stature. This high percentage indicates that most cases are caused by newly arising mutations; these cases (not inherited from an affected parent) are referred to as sporadic. Studies have demonstrated that sporadic cases of achondroplasia are almost always caused by mutations inherited from the father (paternal mutations). In addition, the occurrence of achondroplasia is higher among the children of older fathers; approximately 50% of children with achondroplasia are born to fathers…arrow_forwardEach of the four types of structural chromosomal mutations is illustrated below. Label each picture with the type of chromosomal mutation that has occurred.arrow_forwardDuchenne muscular dystrophy (DMD) is an X-linked recessive genetic disease caused by mutations in the gene that encodes dystrophin, a large protein that plays an important role in the development of normal muscle fibers. The Dystrophin gene is immense, spanning 2.5 million base pairs, and includes 79 exons and 78 introns. Many of the mutations that cause DMD produce premature stop codons, which bring protein synthesis to a halt, resulting in a greatly shortened and nonfunctional form of dystrophin. Some geneticists have proposed treating DMD patients by introducing small RNA molecules that cause the spliceosome to skip the exon containing the stop codon (A. Goyenvalle et al., 2004. Science 306:1796–1799). The introduction of the small RNAs will produce a protein that is somewhat shortened because an exon is skipped and some amino acids are missing, but it may still result in a protein that has some function. The small RNAs, antisense RNAs, used for exon skipping are complementary to…arrow_forward
- Discuss the following types of mutations, with reference to specific genetic disorders: i) Chromosomal deletion; ii) Reciprocal translocation; and iii) Haploinsufficiencyarrow_forwardDuchenne muscular dystrophy (DMD) is an X-linked recessive genetic disease caused by mutations in the gene that encodes dystrophin, a large protein that plays an important role in the development of normal muscle fibers. The dystrophin gene is immense, spanning 2.5 million base pairs, and includes 79 exons and 78 introns. Many of the mutations that cause DMD produce premature stop codons, which bring protein synthesis to a halt, resulting in a greatly shortened and nonfunctionalform of dystrophin. Some geneticists have proposed treating DMD patients by causing the spliceosome to skip the exon containing the stop codon. Exon skipping would produce a protein that is somewhat shortened (because an exon is skipped and some amino acids are missing), but might still result in a protein that had some function (A. Goyenvalle et al. 2004. Science 306:1796–1799). Propose a possible mechanism to bring about exon skipping for the treatment of DMD.arrow_forwardWhen a female melanotic fly is crossed with a normal male, the progeny are produced: 123 normal females, 125 melanotic females, and 124 normal males. In subsequent crosses between melanotic females and normal males, melanotic females are frequently obtained, but never any melanotic males. Provide a possible explanation for the inhertiacne of the melanotic mutation (Hint: The cross produces twice as many female progeny as male progeny)arrow_forward
- One of the most famous cases of an X-linked recessive mutation in humans is that of hemophilia found in the descendants of Britain’s Queen Victoria. The pedigree of the royal family indicates that Victoria was heterozygous for the trait; however, her father was not affected, and no other member of her maternal line appeared to carry the mutation. What are some possible explanations of how the mutation arose? What types of mutations could lead to the disease?arrow_forwardFriedreich ataxia (FRDA) is an autosomal recessive, neurodegenerative disease that causes a lack of voluntary coordination of muscle movements. Affected individuals are homozygous for an unusually large number (expansion) of repeats of a trinucleotide sequence (GAA) in the first intron of the X25 gene. Unaffected individuals typically have between 7 and 38 repeats of the trinucleotide (GAAGAAGAAGAA…). FRDA patients have anywhere from 66 to over 1,700 repeats. To understand how the GAA trinucleotide expansion leads to FRDA, researchers looked at X25 gene expression by extracting RNA from affected and unaffected patients and doing a northern blot analysis (see the figure below): In panel “a,” the researchers used a probe to detect X25 mRNA. In panel “b,” the researchers used a probe on a duplicate of the original blot to detect human GAPDH mRNA (GAPDH is an enzyme involved in glycolysis). The sample labeled “YR” is mRNA from yeast cells that was used as a control. Explain…arrow_forwardPrader-Willi syndrome is caused by a mutation in anautosomal maternally imprinted gene. Label the following statements as true or false, assuming that thetrait is 100% penetrant.a. Sons of affected males have a 50% chance of showing the syndrome.b. Daughters of affected males have a 50% chance ofshowing the syndrome.arrow_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
Mitochondrial mutations; Author: Useful Genetics;https://www.youtube.com/watch?v=GvgXe-3RJeU;License: CC-BY