Concept explainers
For decades scientists have been perplexed by different circumstances surrounding families with rare, early-onset auditory neuropathy (deafness). In some families, parents and grandparents of the proband have normal hearing, while in other families, a number of affected (deaf) family members are scattered throughout the pedigree, appearing in every generation. Assuming a genetic cause for each case, offer a reasonable explanation for the genetic origin of such deafness in the two types of families.
Want to see the full answer?
Check out a sample textbook solutionChapter 3 Solutions
Concepts of Genetics (12th Edition)
Additional Science Textbook Solutions
Genetic Analysis: An Integrated Approach (2nd Edition)
LooseLeaf for Integrated Principles of Zoology
Genetics: From Genes to Genomes, 5th edition
Genetics: Analysis and Principles
Microbiology: Principles and Explorations
- 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_forwardDeaf mutism, a form of deafness in humans, is a type in which the individual inherits not only deafness but also the inability to talk. A sample pedigree of deaf mutism is shown in the picture. Provide your explanation for the inheritance of this condition in the two families in generation.arrow_forwardConsider the following pedigree. Solid symbols represent individuals affected by the trait. Assume complete penetrance and non-variable expressivity. II 3 4 III 1 2 3 5 6 a) what is the mode of inheritance of this trait? b) Does the ratio of affected to unaffected offspring in generation III-1 to 1II-4 match the expected ratio for this mode of inheritance? Explain your answer in terms of the expected ratio versus the ratio observed. Give a reason for your answer. No mark is assigned for yes or no)arrow_forward
- This is a typical pedigree for a family that carries neurofibromatosis. Is individual I-2 most likely homozygous or heterozygous? Why? Explain.arrow_forwardThe inheritance pattern of a rare form of Xeroderma pigmentosum is exhibited in the pedigree shown below. The pattern of inheritance of the Xeroderma pigmentosum phenotype suggests what type of inheritance. please explain your reasoning.arrow_forwardThe pedigree below shows three generations of a family that carries albinism, an autosomal recessive genetic disease. In the third generation, a child was born with albinism but the genotypes of the rest of the family are unknown. No other family members have the disease. Assume normal, Mendelian genetics with no new mutations. What are the genotypes of the parents of the affected child? A) There is not enough information to determine their genotypes B) Both are homozygous for albinism C) One is hemizygous and one is heterozygous for albinism D) Both are heterozygous for albinism E) One is homozygous and one is heterozygous for abinismarrow_forward
- Brachydactyly type D is human autosomal dominant condition in which the thumbs are abnormally short and broad. In most cases, both thumbs are affected, but occasionally just one thumb is involved. The pedigree above shows a family in which brachydactlyly type D is segregating. Filled circles and squares represent females and males who have involvement of both thumbs. Half-filled in symbols represent family members with just one thumb affected? (Picture attached) There is evidence of variable expressivity and incomplete penetrance in this family. Which individual is most likely nonpenetrant for the trait? A) III-11 B) IV-1 C) IV-5 D) III-10 E) II-4arrow_forwardWhat feature(s) of this pedigree indicate(s) dominant inheritance?arrow_forwardLorenzo has a double row of eyelashes (MIM 126300) which he inherited from his mother as a dominant trait. His maternal grandfather is the only other relative to have it. Fatima, who has normal eyelashes, marries Lorenzo. The first child, Nicola (girl) has normal eyelashes. Now Fatima is pregnant again and hopes for a child with double eyelashes. What chance does the child have of inheriting double eyelashes? Draw a pedigree of this family.arrow_forward
- The following family pedigree shows individuals afflicted with a metabolic disease. Suppose the male (b) and the female (c) have 2 girls and 2 boys, indicate directly on the pedigree the symbols for these children that would be most consistent with the mode of inheritance observations in the pedigree? II II a b d e IVarrow_forwardTake the example of B-thalassemia, an autosomal recessive genetic disease that particularly affects people from around the Mediterranean. This disease is associated with an anomaly of hemoglobin, a protein essential for the transport of oxygen, which is composed of four chains: two alpha (a) and two beta (B). In case of B-thalassemia, the ẞ chains are produced in insufficient or no quantity in an individual homozygous recessive resulting in insufficient production of overall hemoglobin leading to anemia and other physiological challenges. The gene that controls the synthesis of the ẞ chains is located on chromosome 11. Here is part of the coding portion of this gene (which controls a total of 146 amino acids and of which you only see the portion 36 to 41) and one of the targeted mutations: 1. Give the sequence of amino acids from the template and mutated strands. 2. What type of point mutation is it? 3. Using the principles of the theory of evolution, explain briefly and generally why…arrow_forwardThe complete absence of one or more teeth (tooth agenesis) is a common trait in humans—indeed, more than 20% of humans lack one or more of their third molars. However, more severe tooth agenesis, defined as the absence of six or more teeth, is less common and is frequently an inherited condition. L. Lammi and colleagues examined tooth agenesis in the Finnish family shown in the pedigree below. Q.If IV-2 married a man who had a full set of teeth, what is the probability that their child would have tooth agenesis?arrow_forward
- Human Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage LearningHuman Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning