NOVA scienceNOW: Risky Genetics


NOVA scienceNOW : bad Genetics

classroom activity


Activity Summary
Student teams analyze genetic quiz results for fabricated characters, compare their characters ‘ risks of developing specific diseases, and assess the risks for the adjacent generation .

Learning Objectives
Students will be able to :

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  • Define the terms genotype, homozygous, heterozygous, recessive, and dominant
  • Apply the above terms to diseases with different inheritance patterns
  • Differentiate between genic risk and life style risk, in the context of disease
  • Demonstrate the use of Punnett squares to predict the probabilities of finical genotypes in a future generation
  • Construct a three-generation pedigree
  • Discuss how disease can be affected by life style
  • Debate the pros and cons of genetic testing

Suggested Time
One class period

Materials
Multimedia Resources
Additional Materials

  • Risky Genetics Student Handout (PDF)
  • Pedigrees for Risky Genetics blackline master (PDF)
  • A six-sided die for each pair of students

Background
Can genetic testing bode who will get a particular disease ? The answer depends on the disease, how it is inherited, and whether or not it is influenced by other factors. For every gene, we inherit one copy, known as an allele, from each parent. Alleles can come in different forms, and some are harmful enough to cause diseases .
Some diseases are just caused by a defect in one gene. For example, a type of lung disease known as Alpha-1 Antitrypsin Deficiency is caused by a bad SERPINA1 gene. normally, this gene codes for an enzyme called alpha-1 antitrypsin that protects the lungs against deterioration. In healthy people, two normal, prevailing alleles produce batch of the enzyme. But if two damaged, recessive alleles are inherited, then the person does not produce enough of the enzyme, and his or her lungs lento deteriorate over a life. If one copy of each type of allele is inherited ( one normal-dominant and one damaged-recessive ), then an average sum of the enzyme is produced, which is normally adequate to protect the lungs. however, if a person is a heavy smoker or works in a dust-filled factory, austere problems could start early. This is an example of when familial test can not predict the badness of the disease or when it will strike, because environmental factors can have a powerful influence on homo health .
other genetically caused diseases are more complicated. A specific character of Alzheimer ‘s disease, which causes mental deterioration, is powerfully linked to the gene PSEN1. A person with a dominant allele disease allele will about surely get “ early attack ” Alzheimer ‘s disease, which occurs before the historic period of 65, because a harmful protein builds up within the brain. however, Alzheimer ‘s disease that develops late in life is still ill sympathize. Scientists have discovered respective genes involved, but details remain bleary.

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In another exemplar, two genes—BRCA1 and BRCA2—are powerfully linked to breast and ovarian cancer. prevailing disease alleles for either gene lead to a quintuple increase in women ‘s risk of the disease, and even increase cancer risk for men. however, not all women with the disease alleles will get breast cancer, and not all women with summit cancer have these specific alleles. What accounts for this pas seul ? many genes are involved in cancer, as are health and environmental factors such as smoking habits and toxic pollution. Scientists are still looking for answers .
People may find genetic testing valuable, depending on the specific diseases they are interest in and their motivations. For model, familial testing for alpha-1 antitrypsin lack, or for breast cancer, could give a person important insights into his or her health, leading to more diligent cover and better prevention and treatment. however, testing for early-onset Alzheimer ‘s disease could result in a person feeling despair over a condition for which there is presently no treatment or cure. Some people choose genetic screen for other reasons, such as for help in deciding whether to have children or to contribute to inquiry focused on learning about a disease and developing cures .
In this activity, students play the role of doctors interpreting patients ‘ genic test results. They create characters, analyze genic test results for three diseases, compare their characters ‘ risks of developing specific diseases, and assess the risks for the adjacent coevals .

Procedure
Before the Lesson
The Lesson