Pedigree of a mitochondrial disease II One key finding is that the “root" of the human mtDNA tree is in Africa, suggest- ing that Homo sapiens originated in Africa and from there dispersed throughout the world (see Chapter 18). FIGURE 3-25 This pedigree shows that a human mitochondrial disease is inherited only from the mother.

Pedigree of a mitochondrial disease II One key finding is that the “root" of the human mtDNA tree is in Africa, suggest- ing that Homo sapiens originated in Africa and from there dispersed throughout the world (see Chapter 18). FIGURE 3-25 This pedigree shows that a human mitochondrial disease is inherited only from the mother.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter4: Pedigree Analysis In Human Genetics

Section: Chapter Questions

Problem 8QP: Analysis of Autosomal Recessive and Dominant Traits In the following pedigree, assume that the...

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In 2018, scientists published a paper describing three unusual human families where some individuals ex- hibited biparental inheritance of mitochondria. The researchers made this discovery by determining the base-pair sequences of the mtDNAs of many individ- uals in each family, and the results are shown in the three pedigree diagrams that follow. The filled-in (blue) symbols represent family members who inher- ited mtDNAs from both of their parents. a. The scientists who authored this study suggest that the data hint at the following model: The transmis- sion of paternal mtDNA to the zygote depends on transmission of an autosomal dominant mutant al- lele through the male germ line. Which aspects of the pedigrees are consistent with this hypothesis? b. The precise mechanism by which paternal mitochon- dria are normally excluded from human zygotes is unknown. If the hypothesis in part (a) is correct, what do these results suggest about the mechanism?
Diamond–Blackfan anemia (DBA) is a rare, dominant geneticdisorder characterized by bone marrow malfunction, birthdefects, and a predisposition to certain cancers. Infants withDBA usually develop anemia in the first year of life, have lower thannormal production of red blood cells in their bone marrow, and havea high risk of developing leukemia and bone cancer. At the molecularlevel, DBA is caused by mutations in any one of 10 genes thatencode ribosomal proteins. The first-line therapy for DBA is steroidtreatment, but more than half of affected children develop resistanceto the drugs and in these cases, treatment is halted. DBA canbe treated successfully with bone marrow or stem cell transplantsfrom donors with closely matching immune system markers. Transplantsfrom unrelated donors have significant levels of complicationsand mortality. A couple with a child affected with DBA undergoes in vitro fertilization (IVF) and genetic testing of the resulting embryos to ensure that the embryos…
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Tay–Sachs disease is caused by loss-of-function mutations ina gene on chromosome 15 that encodes a lysosomal enzyme.Tay–Sachs is inherited as an autosomal recessive condition.Among Ashkenazi Jews of Central European ancestry, about1 in 3600 children is born with the disease. What fraction ofthe individuals in this population are carriers?
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In 1979, bones found outside Ekaterinburg, Russia, were shown to bethose of Tsar Nicholas and his family, who were executed in 1918 by aBolshevik firing squad in the Russian Revolution. To prove that the skeletons were those of the royalfamily, mtDNA was extracted from the bone samples, amplified byPCR, and compared with mtDNA from living relatives of the tsar’sfamily.a. Why was DNA from the mitochondria analyzed instead of nuclearDNA? What are some of the advantages of using mtDNA for this type ofstudy?b. Mitochondrial DNA from which living relatives would provide usefulinformation for verifying that the skeletons were those of the royal family?
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In an in situ hybridization experiment, a certain clonebound to only the X chromosome in a boy with no diseasesymptoms. However, in a boy with Duchenne musculardystrophy (X-linked recessive disease), it bound to theX chromosome and to an autosome. Explain. Could thisclone be useful in isolating the gene for Duchenne muscular dystrophy?
In the Human Genome Project, researchers have collectedlinkage data from many crosses in which the male washeterozygous for molecular markers and many crosses wherethe female was heterozygous for the markers. The distancebetween the same two markers, computed in map units, isdifferent between males and females. In other words, thelinkage maps for human males and females are not the same.Propose an explanation for this discrepancy. Do you think thesizes of chromosomes (excluding the Y chromosome) in humanmales and females are different? How could physical mappingresolve this discrepancy?