TRACING GENETIC ANCESTRY USING DNA MICROARRAYS
Name: Lisa Yee
Class/Subject: Biology/ Biotechnology and/or Gene Technology
Student Objectives/Student Outcomes:
1. Read and discuss an article about genetic ancestry and genetic ancestry testing.
2. Apply knowledge of DNA and heredity to understand DNA microarrays, and concepts
of genetic mutation and ancestry tracking.
3. Mimic the function of a DNA microarray used for genetic ancestry analysis by
completing a paper-and-pencil activity.
4. Discuss the ethics of genetic testing in medical research.
• Copies of the Online NewsHour article "Science of DNA Kits" available at
• Copies or transparency of the genetic migration map (printer-friendly PDF).
• Copies or transparency of the example DNA microarray procedure (printer-
• Copies of student worksheet and instructions: Tracing Human History Using
Mitochondrial DNA (printer-friendly PDF)
• Copies of the four DNA sample strands (printer-friendly PDF) (one set of four
DNA samples per group), which could be photocopied on colored paper (printer-
friendly PDF), or laminated, cut and put into envelopes.
• Copies of the microarray master grid (printer-friendly PDF) (one per group).
• Copies of the microarray analysis grids (printer-friendly PDF) (one per student).
• Copies of homework questions (printer-friendly PDF) (optional).
• Answer key (printer-friendly PDF).
• Tape or glue sticks
• Projector (optional, for transparencies)
• Download all materials as one file (printer-friendly PDF).
• Full coverage of the "Search for Ancestors" by the Online NewsHour, including
NewsHour with Jim Lehrer TV segments, is available at
Introduction/Overview: This is an activity that can be used in a unit on gene technology
or biotechnology. Students should already have had exposure and knowledge base on
heredity and DNA, more importantly a lab on DNA extraction. The purpose of this
activity is to introduce students to the concept of “ancient” ancestry, which goes further
than having students describe a particular country they are from. Although human DNA
is 99.9% the same amongst all, scientists are able to determine from that .1% certain
“genetic markers” in the form of single nucleotide mutation sequences. Scientists have
taken this information and reconstructed human migration maps dating back to a genetic
"Eve." Now, many companies offer tests that use DNA microarrays, also called gene
chips, to compare these DNA markers in samples with those found in hundreds of
ancestral groups. The result is a personal genetic profile that can be used to give
information about the geographic component of a person's past.
Website: This lesson plan is based on PBS News Hour Extra website:
5 min. Start of Class: Basic review of concepts of DNA, heredity and mutation by
think-pair-share activity or simple quiz would ensure all students have
knowledge base and highlight those that do not for further help.
3 min. Introduction of Lesson: Journal Question: How could you use DNA to find
out about human history?
• What is it about DNA that makes each of us unique? Scientists have
figured out that .1% of DNA is different amongst humans. Even this
small percentage gives many phenotypic differences.
• What sort of information about humans can you get from DNA?
Which gene sequences may be related to particular diseases, traits,
• Where do mutations come from? With constant replication and
millions of gene sequences, there is always chance for mutation in
sequence replication during cell division or transcription/translation.
• Can heredity apply to mutations? Sure, these mutations get passed on
to offspring. This is the basis of evolution.
• What is "junk DNA?" DNA sequences that are not used during
replication or protein synthesis.
• Can "junk DNA" have heritable mutation?
***Students may not answer all of these questions, but it is important for
them to at least think about these questions and then work them out later.
45 min. Lesson Instruction:
3. Distribute and/or share the Online NewsHour article entitled, "DNA Kits
Provide Picture of Past" available at
(This article could be handed out at the end of the previous class).
Encourage students to actively read and let them know they will be
assessed on this.
As a class, read the article and discuss the use of genetic markers in the
field of genetic genealogy. Review vocabulary when needed.
4. Show the genetic migration map. Point out that the letters on the map
correspond to some mitochondrial DNA (mtDNA) haplogroups. Then, using
the map, ask the students to:
• Identify the time and location of "mitochondrial Eve". Discuss how
scientists could have analyzed mitochondrial DNA to determine the
existence of this maternal ancestor.
• Identify the approximate times at which human first expanded into the
following continents: Asia, Australia, Europe, North America, South
• Determine which continent was populated first? Which continent was
populated most recently?
• Postulate why the continents were populated in the pattern shown on
• Think about how migration patterns changed due to climate change,
specifically after the end of the last ice age (about 10,000 years ago).
5. Revisit the opening question: How could you use DNA to find out about an
2 min. Start of Class: Ask students for any remaining questions from the previous day.
50 min. Lesson Instruction:
1. Tell students they will be using an on-paper version of a DNA microarray
to determine human ancestry.
2. Review concepts of heritable mutation, and how mutations in DNA can be
used to trace ancestry, DNA microarrays and DNA base pairing.
3. Split the class into teams of four students, and provide one set of materials
for each group:
• a copy of the instructions and worksheet, microarray grid master,
microarray analysis grids and the four human cDNA fragments.
Provide guidance for the exercise. You may assign 1 of the 4 DNA
strands to the students or they can pick strands in groups.
• Leave the DNA microarray procedure on an overhead projector as the
students do the activity. Students can color, using different colored
pencils, each human cDNA sequences.
• After the students have 'hybridized' the genes onto the Microarray
Grid Master, they will be able to analyze their results and determine
the ancestry of each of the four humans.
4. Discuss the results and assign homework activities (optional). Collect the
worksheets at the end of the class.
Assessments/Checks for Understanding: