Concept explainers
Xerodermapigmentosum (XP) is an autosomal recessive condition characterized by moderate to severe sensitivity to ultraviolet (UV) light. Patients develop multiple skin lesions on UV-exposed skin, and skin cancers often develop as a result. XP is caused by deficient repair of DNA damage from UV exposure. a. Many genes are known to be involved in repair of UVinduced DNA damage, and several of these genes are implicated in XP. What genetic phenomenon is illustrated by XP? b. A series of
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- Familial retinoblastoma, a rare autosomal dominant defect, arose in a large family that had no prior history of the disease. Consider the following pedigree (the darkly colored symbols represent affected individuals): a. Circle the individual(s) in which the mutation most likely occurred. b. Is the person who is the source of the mutation affected by retinoblastoma? Justify your answer. c. Assuming that the mutant allele is fully penetrant, what is the chance that an affected individual will have an affected child?arrow_forwardMelanoma, 45 Colon cancer, 40 Sarcoma, 45 Breast Lung cancer, 53 cancer, 32 Stomach cancer, 50 Brain cancer, 18 Osteosarcoma, 3 Leukemia, 19 Rhabdomyosarcoma, 14 Answer the following subparts :- A. What do you notice in this pedigree as compared to Rb or BRCA1/2? B. Why do you think that so many cancer types are associated with inherited defects in p53? Please need detailed answer I want to learn please please I will upvote god promise|arrow_forwardTwo 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.arrow_forward
- A. Look at the pedigree, and DISREGARD individual II-8 for the moment. Is the pattern of inheritance of Unetan syndrome dominant or recessive? You may assume that the gene is FULLY-PENETRANT in this family. Please give two specific reasons that support your conclusion. B. Now, looking at BOTH the pedigree AND at the Southern blot, is this trait autosomal, X-linked, or Y-linked? Please give two specific reasons that support your conclusion. Once again, disregard II-8 for the moment. One of your two reasons must refer specifically to evidence present in the Southern blot. C. Define the gene alleles associated with Unetan syndrome. Your alleles MUST be consistent with the pattern of inheritance, AND your genetic notation must be consistent with that used throughout the course. Unetan syndrome allele: ________ Normal allele: ________arrow_forwarddetermining coat color is the agouti gene?arrow_forwardWhat unsual phenomenon is at work in each of the following disorders?arrow_forward
- Hemophilia A is caused by a sex-linked recessive gene in human and in dogs. a. What proportions (and sexes), among their offspring will be hemophiliacs if a hemophilic male is mated to a homozygous nonhemophilic female?b. If a daughter produced by the mating in (a) is mated to a normal male, what proportions and (sexes) will be hemophilic among their offspring?arrow_forwardIn retinoblastoma, a mutation in one allele of the RB1 tumorsuppressorgene can be inherited from the germ line, causingan autosomal dominant predisposition to the developmentof eye tumors. To develop tumors, a somatic mutation in thesecond copy of the RB1 gene is necessary, indicating that themutation itself acts as a recessive trait. Given that the firstmutation can be inherited, in what ways can a second mutationalevent occur?arrow_forwardTalk about the challenges involved in determining the genetic components of polygenic illnesses. Explain complementation groups and how the biochemical underpinnings of disease are determined using them. Hereditary illnesses of genomic instability include Werner syndrome, Bloom syndrome, XP, ataxia-telangiectasia, and Fanconi anemia. Which of these ailments has molecular mechanisms behind it? Which kind of genetic instability is connected to which disorder?.arrow_forward
- Lesch-Nyhan syndrome is due to a mutation in a gene that encodesa protein called hypoxanthine-guanine phosphoribosyltransferase(HPRT). HPRT is an enzyme that functions in purine metabolism.People afflicted with this syndrome have severe neurodegenerationand loss of motor control. The pedigree below contains severalindividuals with Lesch-Nyhan syndrome, shown with blacksymbols. Based on this pedigree, does this syndrome appearto be inherited by an autosomal recessive, autosomal dominant,X-linked recessive, or X-linked dominant pattern? Explainyour reasoning.arrow_forwardBased on the figure below: If children with hereditary retinoblastoma often survive until adulthood and produce children, what is their risk of developing other types of tumors later in life? What is a risk for their children of developing retinoblastoma? Is there the tendency to develop retinoblastoma inherited as a dominant trait or as a recessive trait? Is there one mutant copy sufficient to predispose a person to develop the cancer or two copies are needed to develop retinoblastoma as a cancer?arrow_forwardLeber 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_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning