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3 – 4 45-minute class periods
One of our strongest desires as humans is to know our roots – where we came from, and why we are the way we are. In recent years, we have been able to discover more information about ourselves than ever before, thanks to the sequencing of the human genome. Biologists, geneticists, historians and genealogists have all studied this fascinating and complex structure to find out what it can tell us about ourselves and our origins.
This lesson, using clips from the PBS series FACES OF AMERICA, explores the various types of genetic information contained in the human genome. The Introductory Activity examines the structure and composition of chromosomes and DNA, and can be used as a review or introduction to the topic. Following that, students will participate in a hands-on activity reviewing basic Mendelian genetics and the difference between genotype and phenotype. Students will also learn about different ways of tracing ancestry through DNA, and apply that to patterns of human migration and genetic population sets known as haplogroups. In the Culminating Activity, students will develop methods for determining the genetic heritage of their class, school, or community.
Life Science, Biology, Genetics
Students will be able to:
• Identify chemical and structural properties of DNA;
• Define “genotype” and “phenotype,” and explain the difference between the two;
• Describe how Y-chromosome DNA and mitochondrial DNA are used to trace ancestry and family lineage;
• Recognize and identify discrete population groups and paths of human migration;
• Develop a scientific investigation to determine the ethnic heritage of a large group of people.
National Science Education Standards
SCIENCE AS INQUIRY
Content Standard A
As a result of activities in grades 9–12, all students should develop:
• Abilities necessary to do scientific inquiry
o Identify questions and concepts that guide scientific investigations.
• Understandings about scientific inquiry
o Scientists usually inquire about how physical, living, or designed systems function. Conceptual principles and knowledge guide scientific inquiries. Historical and current scientific knowledge influence the design and interpretation of investigations and the evaluation of proposed explanations made by other scientists.
o Scientists rely on technology to enhance the gathering and manipulation of data. New techniques and tools provide new evidence to guide inquiry and new methods to gather data, thereby contributing to the advance of science. The accuracy and precision of the data, and therefore the quality of the exploration, depends on the technology used.
o Results of scientific inquiry—new knowledge and methods—emerge from different types of investigations and public communication among scientists. In communicating and defending the results of scientific inquiry, arguments must be logical and demonstrate connections between natural phenomena, investigations, and the historical body of scientific knowledge. In addition, the methods and procedures that scientists used to obtain evidence must be clearly reported to enhance opportunities for further investigation.
Content Standard C
As a result of their activities in grades 9-12, all students should develop understanding of:
• The cell
o Cells store and use information to guide their functions. The genetic information stored in DNA is used to direct the synthesis of the thousands of proteins that each cell requires.
• Molecular basis of heredity
o In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T). The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular ”letters”) and replicated (by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.
o Most of the cells in a human contain two copies of each of 22 different chromosomes. In addition, there is a pair of chromosomes that determines sex: a female contains two X chromosomes and a male contains one X and one Y chromosome. 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.
o 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. Only mutations in germ cells can create the variation that changes an organism’s offspring.
• Biological evolution
o The millions of different species of plants, animals, and microorganisms that live on earth today are related by descent from common ancestors.
Clip 1: Frenetic Genetics
This segment includes examples of the types of genetic information contained in the human genome – physical traits, behaviors, and propensity for diseases.
Clip 2: All in the Family
This segment details the process of documenting family history and tracing lineage back through maternal and paternal lines.
Clip 3: Migration Sensations
This segment details the process of human migration through haplogroups, and shows the haplogroups of some of the series’ guests.
Clip 4: A Piece of the Pie
This segment covers what DNA can tell us about our ethnic identities that regular genealogy might not.
Access the streaming and downloadable video segments for this lesson at the Video Segments Page.
NOVA Online | Cracking the Code of Life | Journey into DNA
This interactive explores the structure of DNA, and DNA’s relationship to the human body as a whole.
National Geographic Genetic Signposts
An online interactive developed for the Genographic Project that explains the different types of DNA passed down through generations.
Tracing Ancestry with mtDNA
This chart shows the genetic relationships between 16 individuals over six generations.
This online interactive shows users how DNA mutations affect future generations.
Atlas of the Human Journey
This interactive timeline provides a comprehensive overview of the major y-chromosome DNA and mtDNA haplotypes found in humans over the past 200,000 years.
For each student:
• Journey into DNA Student Organizer (download here)
• What’s Your Genotype? Student Organizer (download here)
• Atlas of the Human Journey Student Organizer (download here)
• Genetic Heritage Investigation Student Organizer (download here)
• Computer, if available
For each pair or group:
• Computer, if not available for each student
For the class:
• Computer, projector, screen
• Interactive whiteboard or overhead projector
• Journey into DNA Student Organizer Answer Key (download here)
• What’s Your Genotype? Student Organizer Answer Key (download here)
• Atlas of the Human Journey Student Organizer Answer Key (download here)
PREP FOR TEACHERS:
Prior to teaching this lesson, you will need to:
Preview all of the video segments and websites used in the lesson.
Download the video segments used in the lesson to your classroom computer, or prepare to watch them using your classroom’s Internet connection. Make sure the Flash plug-in (available free at www.adobe.com) is downloaded and installed on each computer that you or your students will be using in the lesson.
Bookmark the websites used in the lesson on each computer in your classroom. Using a social bookmarking tool such as del.icio.us or diigo (or an online bookmarking utility such as portaportal) will allow you to organize all the links in a central location.
Print enough copies of each organizer for each student in your class, and print the answer keys for your reference.
Note: In order to effectively conduct Learning Activity 3, class must have access to a computer lab or computers in the classroom. Students must be able to work at computers individually, in pairs, or in groups.
Lesson plans for FACES OF AMERICA were created by the LAB@Thirteen, Thirteen’s Community and Educational Outreach Department.