Concept explainers
Down syndrome is usually caused by having a complete extra copy of chromosome 21. The syndrome encompasses many different traits including low IQ, heart disease, characteristic facial features, gastrointestinal tract abnormalities, short stature, poor muscle tone, and increased risk of leukemia and dementia. Some people diagnosed with Down syndrome display only a subset of these anomalies. These people often have one normal chromosome 21 and one chromosome 21 containing a duplication; the region of chromosome 21 that is duplicated can differ among individuals.
Some scientists think that one critical region of chromosome 21 exists (containing one or a few genes) that is responsible for Down syndrome. Researchers have used individuals with duplication Down syndrome to test this idea. Suppose that using genome sequencing, scientists determined which parts of chromosome 21 were present in three copies in eight individuals with duplication Down syndrome. A summary of the data is shown in the table that follows. An X indicates that the given individual is affected by the particular abnormality listed in the column heading.
a. | Do the data support or refute the hypothesis that chromosome 21 contains a single Down syndrome critical region? Explain. |
b. | Do the data support the idea that each Down syndrome abnormality is caused by overexpression of a different region of chromosome 21? Explain. |
Want to see the full answer?
Check out a sample textbook solutionChapter 13 Solutions
Genetics: From Genes to Genomes
- Find out about the organisations and the movements aimed at the conservation of our natural resources. Eg Chipko movement and Greenpeace. Make a project report on such an organisation.arrow_forwardWhat are biofertilizers and mention the significancearrow_forwardPCBs and River Otters: Otters in Washington State’s Green-Duwamish River have high levels of polychlorinated biphenyls (PCBs) in their livers. PCBs can bind to the estrogen receptors in animals and disrupt the endocrine system of these otters. The PCBs seem to increase the estrogen to androgen ratio, skewing the ratio toward too much estrogen. How would increased estrogen affect the river otter population? Based on your reading of the materials in this unit, what factors can affect fertility in humans? Explain how each of the factors affecting human fertility that you described can disrupt the human endocrine system to affect reproduction.arrow_forward
- Other than oil and alcohol, are there other liquids you could compare to water (that are liquid at room temperature)? How is water unique compared to these other liquids? What follow-up experiment would you like to do, and how would you relate it to your life?arrow_forwardSelection of Traits What adaptations do scavengers have for locating and feeding on prey? What adaptations do predators have for capturing and consuming prey?arrow_forwardCompetition Between Species What natural processes limit populations from growing too large? What are some resources organisms can compete over in their natural habitat?arrow_forward
- Species Interactions Explain how predators, prey and scavengers interact. Explain whether predators and scavengers are necessary or beneficial for an ecosystem.arrow_forwardmagine that you are conducting research on fruit type and seed dispersal. You submitted a paper to a peer-reviewed journal that addresses the factors that impact fruit type and seed dispersal mechanisms in plants of Central America. The editor of the journal communicates that your paper may be published if you make ‘minor revisions’ to the document. Describe two characteristics that you would expect in seeds that are dispersed by the wind. Contrast this with what you would expect for seeds that are gathered, buried or eaten by animals, and explain why they are different. (Editor’s note: Providing this information in your discussion will help readers to consider the significance of the research).arrow_forwardWhat is the difference between Uniporters, Symporters and Antiporters? Which of these are examples of active transport?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 LearningBiology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning
- Concepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College