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NOVA scienceNOW: Aging

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Before Watching

1. Graph the age demographics of your town or city. Assign student groups different towns or cities in your area, and have each group find the age demographics by decades (e.g., 0-10; 11-20, etc.) for their assigned location. (For some towns, this information is on the Internet; for others, the information can be obtained from the town or city census office.) Then ask groups to display the information in a bar graph. Have them label the x-axis "Age by Decade" and the y-axis "Percent of Population." Ask students to display their graphs. Is the number of centenarians greater than, less than, or equal to 1/10,000 (0.01 percent) as is stated in the program? Have students consider factors that may have contributed to higher or lower percentages (ratios) than 1/10,000 (assisted-living centers for seniors, extremely harsh climate, or lack of medical care). Extend the activity and have students research and graph the age demographics of cities and towns in areas of the country known to have high populations of senior citizens, such as San Francisco, CA; Boynton Beach, FL; Philadelphia, PA; New York, NY; Lynchburg, VA; and Muncie, IN. Ask how graphs that are made using age demographics from these areas compare to their graphs based on local age demographics.

2. Design a survey. Have students design an anonymous survey to find how many people there are in the extended school community (including family members and other caregivers) over the age of 90. (Do families that include members older than 90 and 100 years old have, or did they once have, more than one member in that age group? Ask students to include a question in the survey about this.) Is the number of people over 100 years of age greater than, less than, or equal to the ratio of 1/10,000? Ask what happens when you take a small sample and try to extend the results to represent a larger population. If there are people in their 90s or centenarians in the extended school community, invite one or more individuals to your classroom and have the class interview them. Before their visit(s), have students prepare interview questions.

3. Brainstorm genetic, environmental, and lifestyle factors that relate to life span. Review the definition of the term life span. (The average length of time, often expressed in a range, that a species in a particular environment can be expected to survive.) Have student pairs brainstorm and list factors that may play a role in determining whether individuals reach their expected life span. Then have them group the factors as mostly genetic (inherited), mostly environmental (pollution and other external factors), and mostly lifestyle (smoking, amount and kind of exercise, drug use, dietary choices). Make a three-column chart on the board, and label one column genetic factors, one environmental factors, and one lifestyle choices. Have teams share the factors they came up with and list them on the board. Review the list with students and discuss the ways genes, the environment, and lifestyle can affect how long a person lives.

After Watching

1. Research organisms used for laboratory research. Have students recall the laboratory organisms discussed in the program that are used to study genes related to aging and longevity (yeast; C. elegans, a common roundworm; mice; and, briefly mentioned, Drosophila, a fruit fly). Divide the class into four groups, and assign each group a different organism to research (see Howard Hughes Medical Institute site in Links & Books). Groups should find out why their organism is so widely used and important for genetic studies. Have each group prepare and present a poster about their organism. Posters should include the information listed below.

   • organism's classification
   • length of time required for the organism to reproduce
   • organism's habitat and availability
   • how and where the animals are kept in the laboratory
   • how long the organism generally lives
   • reasons why the organism is frequently used for genetic research (for example, the functions of many of the organism's genes are already known)

2. Consider why DNA needs repair genes. The scientists in the program report that sirtuin genes in yeast are active when an organism is stressed, such as when food intake is low; a different scientific study showed that damage to the Daph 2 gene in the roundworm C. elegans caused a decrease in the worm's insulin level. The researchers postulate that both sirtuin and low insulin may trigger "survival genes" to become active or expressed. The scientists state that "survival genes" probably include DNA repair genes. Ask students why DNA might need its own set of repair genes. (DNA can be changed during replication or damaged by UV light and environmental toxins such as cigarette smoke or other inhaled or ingested toxins. Therefore, it is important that genes exist that can repair the damage to this basic building block of life.)

   As an extension for advanced biology students, use a DNA model and have students locate the sugar-phosphate backbone, the individual nucleotide bases, and the nucleotide base pairs. Ask students to brainstorm different break points that could occur in DNA that would need repair. Tell students that a number of DNA repair genes are involved in the following: base excision and replacement, mismatch repair, and rejoining broken strands. Have students use the model to show the three types of repair. What might happen to the cell if a DNA repair mechanism didn't exist? (Cells and organs could die. Cells might make too little or too much of a protein. If the damage were to affect a gene that controls cell division, the cell could continue to divide, resulting in a tumor or in cancer.)

3. Research plant chemicals that have health benefits. Scientists researching longevity found that resveratrol, in high doses, caused yeast, roundworms (C. elegans), and mice to live longer than their expected life span. Resveratrol is made by plants to protect them from fungal growth. It is found in different amounts in grapes (mainly in the skin), raspberries, peanuts, cranberries, and other plants. Many plant chemicals have a beneficial effect on health. Divide the class into groups and have each group research resveratrol or one of the following groups of plant chemicals—the flavonoid anthocyanin (found in blueberries, blackberries, cherries, and some vegetables such as red cabbage); or the flavonoid quercitin (found in yellow onions). Have students report on the function their chemical plays in the plant, and the potential health benefits of the chemical for people. Note: Explain that information about health benefits should be obtained from encyclopedias or scientific research sites, because health claims can be false or unsubstantiated.

As an extension, ask students to keep a record of the fruits and vegetables they eat for two days. Have them research and group any foods that contain the plant chemicals in the chart.

Links

HHMI Online Companion
www.hhmi.org/resources/science_now/aging.html
The Howard Hughes Medical Institute offers an extensive collection of aging research resources in its online companion to this episode of NOVA scienceNOW.
More on HHMI and its partnership with NOVA

Healthy Aging for Older Adults
www.cdc.gov/aging
The Centers for Disease Control and Prevention provides this extensive Web site on aging for older adults. Find information on healthy living, view medical statistics, and browse other online resources.

National Institute on Aging
www.nia.nih.gov/ResearchInformation/
This Web site from the National Institutes of Health offers information on current research into the biology of aging, behavioral and social aspects of old age, and more.

The Aging Research Center
www.arclab.org/
On this Web site, learn about upcoming conferences on geriatrics research, read up on federally and privately supported clinical research, and find a list of online aging resources.

Infoaging
www.infoaging.org
This Web site from the American Federation for Aging Research has information on the biology of aging, age-related diseases, and links to current research.

Genes and Longevity
www.dnafiles.org/resources/res12.html
This companion Web site to the National Public Radio series "The DNA Files" provides a number of links and other online resources related to longevity and aging.

Books

Epigenetics
by C. David Allis. Cold Spring Harbor Laboratory Press, 2006.

Ageless Quest: One Scientist's Search for Genes That Prolong Youth
by Lenny Guarente. Cold Spring Harbor Laboratory Press, 2002.

Aging at the Molecular Level: Biology of Aging and its Modulation
edited by T. von Zglinicki. Springer Books, 2003.

Articles

"A Conversation With Nir Barzilai; It's Not the Yogurt: Looking for Longevity Genes"
by Claudia Dreifus. The New York Times, February 24, 2004.

"The Quest For a Way Around Aging"
by Nicholas Wade. The New York Times, November 8, 2006.