Look over the 10 diseases approved for genetic health risk assessment listed in Application Chapter B. Select one disease other than the three discussed in Application Chapter B or in this chapter (alpha-1 antitrypsin deficiency, late-onset Alzheimer disease, and celiac disease) or another of the diseases of your choice. Do a brief Internet search to find and download (1) one article for a nonscientific audience identifying the gene or genes whose alleles are associated with occurrence of the disease and (2) one scientific paper that provides data supporting the association of specific alleles of the gene or genes with the disease. Write a short summary combining the information contained in the two papers.

Why might mitochondrial, Y chromosome, and autosomal DNA provide different perspectives on our evolutionary past, for example, with respect to our relationship with Neanderthals?

What insights have analyses of human mitochondrial DNA provided into our recent evolutionary past?

What lines of evidence support the hypothesis that modern humans evolved in Africa and then subsequently migrated throughout the globe?

Discuss how both gains and losses of regulatory elements may lead to human-specific traits.

Carl Linnaeus, the 18th-century botanist who laid the foundation for the modern system of taxonomic nomenclature, placed chimpanzees and humans in the same genus. Discuss the merits of this classification.

How do copy-number variants arise? Do they account for more polymorphism than SNPs within the human population?

Consider possible societal and ethical dilemmas that might arise if we currently shared the planet with another hominin.

Describe how selection at a locus can result in a loss of polymorphism surrounding the locus.

How can ancient DNA provide insight into past migrations that analyses of extant human genomes fail to uncover?

Denisovans are known from bones found in Denisova Cave in the Altai Mountains in Siberia, but traces of their DNA are found in Australians and Melanesians, whose ancestors likely migrated across Asia much farther to the south. How can these geographic differences be reconciled?

In Island Melanesia and Polynesia, most mtDNA haplotypes are of Asian ancestry, whereas Y chromosome haplotypes are predominantly New Guinean. Provide a hypothesis for this sex-biased distribution.

When the human genome is examined, the chromosomes appear to have undergone only minimal rearrangement in the 100 million years since the last common ancestor of eutherian mammals. However, when individual humans are examined or when the human genome is compared with that of chimpanzees, a large number of small indels and SNPs can be detected. How are these observations reconciled?

The mtDNA sequence of Neanderthals is more similar to that of modern humans than to that of Denisovans. However, analyses of nuclear DNA clearly indicate that Neandertals and Denisovans share a more recent common ancestor than either of these hominins shares with modern humans. Propose a hypothesis to resolve the discrepancy between the mtDNA and the nuclear genome.

A 9-bp deletion in the mitochondrial genome between the gene for cytochrome oxidase subunit II and the gene for tRNAᴸʸˢ is a common polymorphism among Polynesians and also in a population of Taiwanese natives. The frequency of the polymorphism varies between populations: The highest frequency is seen in the Maoris of New Zealand (98%), lower levels are seen in eastern Polynesia (80%) and western Polynesia (89%), and the lowest level is seen in the Taiwanese population. What do these frequencies tell us about the settlement of the Pacific by the ancestors of the present-day Polynesians?

If you were to compare your genome sequence with that of your parents, how would it differ? If you were to compare your genome sequence with another student's in the class, how would it differ? What additional difference might you see if your genome was compared with that of a sub-Saharan African, or if you are of sub-Saharan African descent, with that of a non-African?

Compare and contrast the terms in each of the following pairs:

Population and gene pool

Compare and contrast the terms in each of the following pairs:

Random mating and Inbreeding

Compare and contrast the terms in each of the following pairs:

Natural selection and Genetic drift

Compare and contrast the terms in each of the following pairs:

A polymorphic trait and a polymorphic gene

Compare and contrast the terms in each of the following pairs:

Founder effect and Genetic bottleneck

Identify and describe the evolutionary forces that can cause allele frequencies to change from one generation to the next.

Describe how natural selection can produce balanced polymorphism of allele frequencies through selection that favors heterozygotes.

Thinking creatively about evolutionary mechanisms, identify at least two schemes that could generate allelic polymorphism in a population. Do not include the processes described in the answer to Problem 4.

Genetic drift, an evolutionary process affecting all populations, can have a significant effect in small populations, even though its effect is negligible in large populations. Explain why this is the case.

The ability to taste the bitter compound phenylthiocarbamide (PTC) is an autosomal dominant trait. The inability to taste PTC is a recessive condition. In a sample of 500 people, 360 have the ability to taste PTC and 140 do not. Calculate the frequency of the recessive allele.