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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)
- The human intestinal tract is home to a vast, diverse microbial community. The bacteria that comprise this microbial community serve a number of important, beneficial functions. However, some bacterial species have been suggested to play a role in certain forms of cancer. One such bacteria is Fusobacterium nucleatum (i.e., F. nucleatum). Investigators wishing to study the role of F. nucleatum in colorectal cancer developed a new assay for detecting these bacteria in tumor tissue. In controlled experiments, the test was highly sensitive in detecting F. nucleatum and also had high specificity. To examine consistency in their test findings, the investigators also conducted repeat tests in 50 tissue samples. From these repeat tests, the investigators observed that the overall number of samples in which F. nucleatum was detected was almost identical (10 out of 50 on the first test vs. 11 out of 50 on the repeat test); for 9 samples, F. nucleatum was detected on both the initial and the…arrow_forwardA laboratory in Japan performed a similar experiment on earthworms from different localities of the Japanese archipelago, but instead of linking trypsin activity within worms to anatomical features, they were interested in geographical differences in the ability of the worms to breakdown environmental pollutants using the enzyme polyphenol oxidase. The protocol was similar to the one you used, except that enzyme activity was measured from 100 µl of worm extract. Data obtained are displayed below: Locality Replicate Amount of product Concentration of total protein in worm extract (µg/ml) liberated over 10 minutes (pmol) Hokkaido 1 101 4 87 3 3 107 4 4 88 3 5 89 Hon-shu 1 126 2 2 120 3 3 156 4 4 153 5 5 119 4 Куu-shu 1 103 4 2 99 5 3 94 4 108 3 5 110 5 Okinawa 1 88 3 2 90 4 3 96 4 100 112 5 5 3 From the data in the table, calculate the specific activity of polyphenol oxidase (in units of umol/min/mg protein) from each locality, presenting the data as mean + standard error (n=5).arrow_forwardRaw red alga of the genus Porphyra is part of a traditionalJapanese diet. This alga is rich in porphyran, a polysaccharide that human digestive enzymes cannot break down. Marine bacteria that live on the alga produce a porphyran-digesting enzyme. In Japan, a homologousenzyme is common in one species of intestinal bacteria. Outside of Japan, people have the same species of intestinal bacteria, but they do not have the gene for the porphyran-digesting enzyme. The marine bacteria andthe intestinal bacteria are not close relatives, so they mostlikely did not inherit the enzyme from a shared ancestor.Propose a scenario to explain the observed distributionof the enzyme.arrow_forward
- A laboratory in Japan performed a similar experiment on earthworms from different localities of the Japanese archipelago, but instead of linking trypsin activity within worms to anatomical features, they were interested in geographical differences in the ability of the worms to breakdown environmental pollutants using the enzyme polyphenol oxidase. The protocol was similar to the one you used, except that enzyme activity was measured from 100 µl of worm extract. Data obtained are displayed below: Replicate Amount of product liberated over 10 Locality Concentration of total protein in worm extract minutes (pmol) (ug/ml) Hokkaido 1 101 4. 2 87 3 3 107 4 4 88 3. 89 Hon-shu 1 126 2. 2 120 3 3 156 153 119 4 Куu-shu 1 103 99 5 3 94 4 108 3 110 5 Okinawa 1 88 3 90 4 3 96 4 100 112 3 From the data in the table, calculate the specific activity of polyphenol oxidase (in units of umol/min/mg protein) from each locality, presenting the data as mean + standard error (n=5). You only need to show 1…arrow_forwardHow would a human cell normally change its expression of the gene for tyrosine aminotransferase? adipose cells will turn on this gene in the presence of glucocorticoids liver cells will turn on this gene in the presence of glucocorticoids liver cells will turn on this gene in the absence of glucocorticoids liver cells will turn off this gene in the presence of glucocorticoids adipose cells will turn off this gene in the absence of glucocorticoidsarrow_forwardAs a clinical microbiologist, your job is to identify an infectious bacterial strain isolated from a patient. Phenotypically, you have discovered that the new bacterial strain can grow in the presence or absence of oxygen. By growing the strain in glucose carbohydrate tubes, you found that the organism is positive for glucose fermentation. After genome sequencing and biochemical analysis, you know that your organism is capable of making all of the enzymes necessary for glycolysis, and that it contains a TCA cycle and an electron transport chain.arrow_forward
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- The cytochrome P450 family of monooxygenase enzymes are involved in the clearance of drugs/medications from our body. Many adverse drug -drug interactions are known to occur as a result of interaction with the cytochrome P450 enzymes. A large number of drugs are metabolized by the enzyme P450 3A4. Human P450 3A4 is known to metabolize midazolam, a sedative, to a hydroxylated product, 1'- hydroxymidazolam. The kinetic data shown below are for the reaction catalyzed by P450 3A4. a. Focusing on the first 2 columns, determine the Km and Vmax for the P450 3A4 enzyme. b. Ketoconazole, an antifungal drug, is known to cause adverse drug interactions when taken along with midazolam. Using the data in the table, determine the type of inhibition caused by ketoconazole. Explain how you arrived at your answer. Midazolam (uM) 00 AN1 2 14 8 Rate of product formation (pmol min-1) 100 156 222 323 Rate of product formation in presence of ketoconazole pmol min-1) 11 18 27 40arrow_forwardSome are unable to taste thiourea and PTC. DNA sequence results for these individuals show a normal predicted amino acid sequence for the TAS2R38 gene. Provide an explanation that can account for insensitivity to thiourea. (a) First assuming a mutation involving the TAS2R38 gene (b) Then assuming a mutation in a gene other than TAS2R38arrow_forwardThe highly pathogenic anaerobic bacterium Clostridium perfringens is responsible for gas gangrene, a condition in which animal tissue structure is destroyed. This bacterium secretes an enzyme that efficiently catalyzes the hydrolysis of the peptide bond indicated in red: where X and Y are any of the 20 common amino acids. How does the secretion of this enzyme contribute to the invasiveness of this bacterium in human tissues? Why does thisenzyme not affect the bacterium itself?arrow_forward
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