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 18, Problem 33P
Recall that Leber congenital amaurosis (LCA), a form of congenital blindness in humans, can 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. | As described in this chapter, gene 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. |
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Fish in a cave system in Mexico is missing its eyes, has thin, translucent skin, and is relatively small (7-10 cm in length).
Can you describe by model why structural changes to genes (mutations) on chromosomes may affect proteins and may result in beneficial effects to the structure and function of the fish?
Can you answer in the following format?
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How Structure and Function is Affected by Mutations in Blind Fish
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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.
Huntington disease (HD) is an inherited neurodegenerative disorder characterized by gradual, irreversible impairment of psychological, motor, and cognitive functions. Symptoms typically appear in middle age, but onset can occur at almost any age, and the course of the disease can range from 15 to 20 years. The molecular basis of HD is becoming better understood, and the genetic mutation has been traced to a gene that encodes a large protein of unknown function. In individuals who will not develop HD, a region of the gene that encodes the N-terminus of this protein has a sequence of CAG codons (for glutamine) repeated 6 to 39 times in succession.
In individuals with adult-onset HD, this codon (3 nucleotides) is typically repeated 40 to 55 times
In those with childhood-onset HD, it is repeated more than 70 times.
*codon: refers to the 3 nucleotides that code for amino acid.
A small portion of the coding sequence of the HD gene is given below. The nucleotide sequence of the DNA is…
Chapter 18 Solutions
Genetics: From Genes to Genomes
Ch. 18 - Match each of the terms in the left column to the...Ch. 18 - Mice are usually gray, but a mouse geneticist has...Ch. 18 - Sometimes, genes transferred into the mouse genome...Ch. 18 - In mice, a group of so-called Hox genes encode...Ch. 18 - The fly eyes shown in Fig. 18.7 are malformed...Ch. 18 - This problem concerns a technique called enhancer...Ch. 18 - Fish and other organisms that live in the Arctic...Ch. 18 - a. Describe two ways you could potentially make a...Ch. 18 - Figure 18.6 shows a picture of Glofish ,...Ch. 18 - Some people are concerned about the possible...
Ch. 18 - The goal of the Knockout Mouse Project is to...Ch. 18 - Prob. 12PCh. 18 - Prob. 13PCh. 18 - a. Which genome manipulation technique would you...Ch. 18 - a. Diagram a knockin construct that could have...Ch. 18 - Prob. 16PCh. 18 - Prob. 17PCh. 18 - The transcription factor Pax6 is required...Ch. 18 - Mouse models for human genetic diseases are...Ch. 18 - One way to determine where inside a cell a protein...Ch. 18 - In Problem 5 in Chapter 17, you saw that a SNP...Ch. 18 - Scientists now routinely use CRISPR/Cas9 to make...Ch. 18 - Geneticists are currently considering using...Ch. 18 - a. Figures 18.9 and 18.12 demonstrated methods to...Ch. 18 - Nonhomologous end-joining NHEJ of a double-strand...Ch. 18 - One problem that researchers sometimes encounter...Ch. 18 - Researchers at the University of California at San...Ch. 18 - Prob. 28PCh. 18 - F. Port and S. Bullock at the University of...Ch. 18 - On Fig 18.14, locate the PAM site and identify the...Ch. 18 - Prob. 31PCh. 18 - Prob. 32PCh. 18 - Recall that Leber congenital amaurosis LCA, a form...Ch. 18 - One potential strategy for gene therapy to correct...Ch. 18 - Recently, scientists have used a mouse model for...
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