DNA Microarray Lesson Plan


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DNA Microarray Lesson Plan

  1. 1. TRACING GENETIC ANCESTRY USING DNA MICROARRAYS Name: Lisa Yee Class/Subject: Biology/ Biotechnology and/or Gene Technology Date: 10/28/2006 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. Content Standards: Materials/Resources/Technology: • Copies of the Online NewsHour article "Science of DNA Kits" available at http://www.pbs.org/newshour/indepth_coverage/science/dna/science.html • Copies or transparency of the genetic migration map (printer-friendly PDF). • Copies or transparency of the example DNA microarray procedure (printer- friendly PDF). • 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). • Scissors • 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 http://www.pbs.org/newshour/indepth_coverage/science/DNA/
  2. 2. 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: http://www.pbs.org/newshour/extra/teachers/lessonplans/science/genetic_ancestry.html Time
  3. 3. 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, etc. • 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 http://www.pbs.org/newshour/indepth_coverage/science/dna/science.html . (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 America. • Determine which continent was populated first? Which continent was populated most recently? • Postulate why the continents were populated in the pattern shown on the map. • 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 individual's history?
  4. 4. Day 2: Materials/Resources/Technology: Time
  5. 5. 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: Closure/Wrap-Up/Review: Self-Assessment (optional):