Concept explainers
The human AMY-1 gene encodes salivary amylase, an enzyme that breaks down starch. The number of copies of this gene varies, and people who have more copies generally make more of the enzyme. In addition, the average number of AMY-1 copies differs among cultural groups.
George Perry and his colleagues hypothesized that duplications of the AMY-1 gene would confer a selective advantage in cultures in which starch is a large part of the diet. To test this hypothesis, the scientists compared the number of copies of the AMY-1 gene among members of seven cultural groups that differed in their traditional diets. The Figure shows their results.
Starchy tubers are a mainstay of Hadza hunter-gatherers in Africa, whereas fishing sustains Siberia’s Yakut. Almost 60% of Yakut had fewer than 5 copies of the AMY-1 gene. What percentage of the Hadza had fewer than 5 copies?
FIGURENumber of copies of the AMY-1 gene among members of cultures with traditional high-starch or low-starch diets.
Source: G. Perry et al. 2007. Diet and the evolution of human amylase gene copy number variation. Nature Genetics 39:1256–1260.
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Chapter 47 Solutions
Biology: The Dynamic Science (MindTap Course List)
- Which of the following statements about Bacillus thuringiensis (Bt) corn are correct? Select all that apply. Question 19 options: Bt corn is only used for animal feed in the United States Bt corn has an inserted bacterial gene in its genome. Bt corn has increased nutritional value and a longer shelf life compared to corn that has not been genetically modified. Bt corn is approved for human consumption.arrow_forwardWhen the O2 supply from blood fails to meet the demand of O2-consuming cells, oxygen deprivation (hypoxia) occurs. This is common, for example,in exercising muscle. It has been recognized for over 100 years that O2-deprived cells show increased conversion of glucose to lactate, known as the Pasteur effect. Activation of the Pasteur effect during hypoxia is mediated by hypoxia-inducible factor-1 (HIF-1). HIF-1 is a transcription factor that upregulates the expression of several glycolytic enzymes that support the increased glycolytic ATP production as mitochondria become starved for O2. At the same time glycolysis is increasing, the rate of mitochondrial respiration decreases. New research reveals that in addition to upregulating enzymes in the glycolytic pathway, HIF-1 also induces the expression of cytoplasmic lactate dehydrogenase (LDH) and mitochondrial pyruvate dehydrogenase kinase (PDK).(a) Explain why glucose consumption must increase in hypoxic tissues toprovide the same amount…arrow_forwardWhen the O2 supply from blood fails to meet the demand of O2-consuming cells, oxygen deprivation (hypoxia) occurs. This is common, for example, in exercising muscle. It has been recognized for over 100 years that O2- deprived cells show increased conversion of glucose to lactate, known as the Pasteur effect. Activation of the Pasteur effect during hypoxia is mediated by hypoxia-inducible factor-1 (HIF-1). HIF-1 is a transcription factor that upregulates the expression of several glycolytic enzymes that support the increased glycolytic ATP production as mitochondria become starved for O2. At the same time glycolysis is increasing, the rate of mitochondrial respiration decreases. New research reveals that in addition to upregulating enzymes in the glycolytic pathway, HIF-1 also induces the expression of cytoplasmic lactate dehydrogenase (LDH) and mitochondrial pyruvate dehydrogenase kinase (PDK).(a) Explain why glucose consumption must increase in hypoxic tissues toprovide the same…arrow_forward
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- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning