SECRETS OF THE DEAD . Lesson Plan . Inherited Immunity

Lesson Plan Index
Inherited Immunity

Inherited Immunity- by Viki Babcock


		(high school science) Students learn about incomplete dominance inheritance by learning about the survivors of the Black Death and completing Punnett Squares. They also discover an important link between this ancient disease and the current menace of AIDS.

Estimated class time

One 90-minute block, or two shorter class periods

Lesson Objectives

Students will:

Learn about the history of the Plague.
Describe how the plague bacteria infected humans.
Define immunity
Illustrate incomplete dominance inheritance using Punnett Squares

Materials needed

Internet access
Copies of Inherited Immunity Punnett Square Activity Sheet.
Video clips are available on the SECRETS OF THE DEAD: Mystery of the Black Death website, but if you wish to purchase the complete program, visit PBS Shop for Teachers http://shop.pbs.org/teachers/products/SEDE742

Teaching Strategy




		Teachers! Video clips for your students are available here. Video Clips

Ask students what it means when someone says "I must be immune to that." Find out through discussion and examples or personal anecdotes what are the students' perceptions about immunity. Ask them why they think some people seem to be immune to some things and others are not.
Direct students to the SECRETS OF THE DEAD Web site at http://www.pbs.org/wnet/secrets/
case_plague/index.html. Read the Background and the Clues and Evidence sections together and discuss the following.
- What led Dr. O'Brien to study the possibility of an inherited immunity to the Black Death?
- What happens on a cellular level when a person who is immune to a certain infectious disease is exposed to that disease?
- Describe some of the problems and obstacles that O'Brien had to overcome to complete his research about the resistance to the plague.
- What is the connection between the historical resistance to the plague and the modern-day threat of AIDS?
Have students view the video clips on the Web site and respond to the questions about each. Discuss as a class or in small groups.
At this point review the concepts of Mendelian genetics and how to use Punnett squares. You may want to direct students to the Baby Step Through the Punnett Square site, if needed. Present the class with some sample crosses that show normal Mendelian inheritance (such as a cross between two individuals that are heterozygous for a widow's peak, or a homozygous recessive non-tongue roller with homozygous dominant tongue roller) and have students create the Punnett Squares on the board or overhead projector.
Ask how the inheritance of plague immunity via the CCR5-D32 gene is different from normal Mendelian genetics. Lead students to the idea that there are three possible phenotypes: death from plague, partial immunity (have symptoms, but survive) and complete immunity. Explain that this is a case of incomplete dominance, in which the heterozygous condition results in an intermediate phenotype, rather than the expression of a dominant allele. Have students become more familiar with the concept of incomplete dominance by completing the Inherited Immunity Punnett Square Activity Sheet.
Have students research to find out about other traits that are passed on via incomplete dominance and create their own Punnett Square probability charts.

Internet Resources

Rx for Survival: Deadly Diseases: Plague
http://www.pbs.org/wgbh/rxforsurvival/series/diseases/plague.html
Evolution: Library: Double Immunity
http://www.pbs.org/wgbh/evolution/library/10/4/l_104_05.html
Plague: Bureau of Communicable Disease
http://www.nyc.gov/html/doh/html/cd/cdpla.shtml
Black Death- Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Black_Death
The Evolutionary History of the CCR5-D32 HIV resistance mutation
http://ib.berkeley.edu/labs/slatkin/novembre/GalvaniNovembreMicInf2005.pdf
Baby Step Through the Punnett Squares
http://www.borg.com/~lubehawk/psquare.htm
Biology Mad A-level Biology: Genetics, Inheritance & Variation
http://www.biologymad.com/GeneticsInheritance/geneticsinheritance.htm

Assessments

Participation in discussion and/or written responses to video clip questions
Completion of Inherited Immunity Punnett Square Activity Sheet
Student created Punnett Squares based on research of incomplete dominance.

Extensions

View the entire video of Mystery of the Black Death, available at Shop PBS at http://www.shoppbs.org/home/index.jsp
Research and write a report on the latest efforts in treating and/or preventing AIDS.
Research the history of the Black Death and create a time-line from the information.

Correlation to National Science Standards

Standards from http://bob.nap.edu/html/nses/html/6e.html#csc912

CONTENT STANDARD C: As a result of their activities in grades 9-12, all students should develop understanding of molecular basis of heredity:

In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA.
Transmission of genetic information to offspring occurs through egg and sperm cells that contain only one representative from each chromosome pair. An egg and a sperm unite to form a new individual. The fact that the human body is formed from cells that contain two copies of each chromosome--and therefore two copies of each gene--explains many features of human heredity, such as how variations that are hidden in one generation can be expressed in the next.
Changes in DNA (mutations) occur spontaneously at low rates. Some of these changes make no difference to the organism, whereas others can change cells and organisms.

CONTENT STANDARD F: As a result of activities in grades 9-12, all students should develop understanding of personal and community health:

The severity of disease symptoms is dependent on many factors, such as human resistance and the virulence of the disease-producing organism. Many diseases can be prevented, controlled, or cured.

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