9 - 12
Three 50-minute class periods
Students will determine the presence of DNA in their food by extracting it from a strawberry. Then, students will compare and contrast GMOs and organic foods in order to evaluate the nutrition, safety, economic, geographic, and environmental impacts of these agricultural production practices.
- GMOs & Organic Foods: Do You Know? Kahoot! quiz
- (Note: Sign up for a free Kahoot account at https://getkahoot.com/. Search the public Kahoot files for “GMOs organic,” and look for the title noted above. Select that Kahoot quiz; the game pin will be displayed for students to access on their smart devices.)
- Smart device for each student, e.g. mobile phone, tablet, computer
- KWL chart (use large poster paper/markers OR whiteboard/whiteboard markers)
- Kahoot Quiz Answer Key
- Strawberry DNA Extraction Lab activity sheet, 1 per student
- Frozen strawberries, 3 per group
- Ziploc sandwich bags, 1 per group
- DNA extracting solution
- In a gallon container mix:
- 1/2 gallon (2000 ml) water
- 1/2 cup (120 ml) clear dish detergent
- 2 tablespoons (30 ml) salt
- Note: Make one day ahead so there are no bubbles in the solution.
- In a gallon container mix:
*These items are included in the Strawberry DNA Necklace Kit, which is available for purchase from agclassroomstore.com.
- Funnels*, 1 per group
- Plastic cups*, 1 per group
- 4" x 4" squares of cheesecloth*, 2 per group
- Graduated test tubes*, 1 per group
- Rubbing alcohol, chilled
- Pipettes*, 1 per group
- Microcentrifuge tubes*, 1 per student
- Yarn*, 1 necklace-length piece per student
- How are GMOs Created? video
- What is a Genetically Modified Food? video
- Intelligence2 debate, Genetically Modify Food
- Decision Matrix, 1 per student
Essential Files (maps, charts, pictures, or documents)
Kahoot Quiz Answer Key
Strawberry DNA Extraction Lab Activity Sheet
transgenic: an organism that contains genes outside its species
recombinant DNA: joining together of DNA molecules from two different species that are inserted into a host organism to produce new genetic combinations
pathogen: a bacterium, virus, or other microorganism that can cause disease
organic food: food grown without the aid of synthetic pesticides or chemical fertilizers, and produced without the use of genetically modified organisms or chemical food additives
genetic engineering (GE): the technical process of inserting or modifying a gene into an existing species, with the help of specific techniques, to enhance the receiving organism
DNA: a molecule that carries most of the genetic instructions used in the development, functioning, and reproduction of all known living organisms
conventional agriculture: refers to methods of farming that include the use of synthetic chemical fertilizers, pesticides, and herbicides; and genetically modified organisms
agricultural biotechnology: a collection of scientific techniques used to improve plants, animals, and microorganisms
genetically modified organism (GMO): the result when a gene from one organism is purposely moved to improve or change another organism
Did you know? (Ag Facts)
- The top genetically modified crops produced in the United States are corn, soybeans, cotton, potatoes, squash, papaya, canola, alfalfa, sugar beets, and apples.1
- There are no genetically engineered wheat varieties for sale or in commercial production in the United States.2
- Currently, 64 countries and the state of Vermont require that genetically modified foods be labeled.3
- Organic agriculture occupies only 1% of global cropland.4
- In spite of lower yields, global organic agriculture is significantly more profitable than conventional agriculture.5
Background - Agricultural Connections
An educated discussion about the pros and cons of genetically modified organisms (GMOs) and organic foods should be based on an understanding of the basic science behind GMOs. The Strawberry DNA Extraction activity in this lesson provides a hands-on explanation of DNA—the “blueprint” that contains the genetic instructions used in the development, functioning, and reproduction of all known living organisms. Scientists use DNA and genetic engineering to insert or modify a gene into an existing species to enhance the receiving organism. This is often accomplished via recombinant DNA in which DNA from two different species are inserted into a host organism to produce new genetic combinations. The results are the production of plants (and sometimes, animals) that result in improved and increased food production.
A GMO results when a gene from one organism is purposely moved to improve or change another organism. This process can be applied to plants, animals, and even humans. Agricultural biotechnology companies apply scientific techniques used to improve plants, animals, and microorganisms. These companies have developed seeds and plants that resist drought, cold temperatures, pests, weeds, and pathogens—bacteria or viruses that can cause disease. Increased yields are realized through the planting of GMO crops. Vitamins and minerals are genetically inserted into foods to boost the foods’ nutrients, e.g., Golden Rice.
When a genetically engineered organism contains genes outside it species, it is considered transgenic. For example, the newly Food and Drug Administration (FDA)-approved AquAdvantage salmon contains a growth hormone gene from the Chinook salmon and a gene from the ocean pout (an eel-like fish) that speeds up the growth rate of the salmon.5
The production of transgenic foods brings up many questions in consumers’ minds. Are these foods safe? What is their impact on the environment? There are three major regulatory agencies in the United States that monitor GMOs in the food supply. “The Food and Drug Administration regulates the safety of food for humans and animals, including foods produced from GE plants. Foods from GE plants must meet the same food safety requirements as foods derived from traditionally bred plants.”6 Traditionally bred plants are grown using conventional agriculture in which farmers may use synthetic chemical fertilizers, pesticides, and herbicides; and GMOs. The United States Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) “…ensure that crops and animals produced through genetic engineering for commercial use are properly tested to make sure they pose no significant risk to consumers or the environment.”7 The Genetic Literacy Project reports that “every major scientific body and regulatory agency in the world has reviewed the research about GMOs and openly declared crop biotechnology and the foods currently available for sale to be safe.”8
Agricultural biotechnology, now often practiced in laboratories, is not a new science. Humans have practiced biotechnology for thousands of years with the earliest domestication of plants and animals occurring approximately 10,000 years ago. Early civilizations used microorganisms to make cheese, bread, yogurt, wine, and beer. Agrarian societies even used selective breeding to enhance desirable traits in offspring.
So, if traditional methods of biotechnology have been successful, why do scientists and farmers utilize genetic engineering? With traditional breeding, plants and animals often exchange large, unregulated pieces of their genetic makeup which “can lead to both useful and unwanted traits in the offspring. Sometimes these unwanted traits can be unsafe.”9 The use of genetic engineering also produces results much faster than traditional breeding. What may have traditionally taken years to produce, can sometimes be achieved with months. GE techniques also “allow new traits to be introduced one at a time without complications from extra genes and extensive crossbreeding.”9
Do consumers who prefer not to eat GMOs have options? Certainly. In recent years, some agricultural producers have made the decision to produce organic food which is grown without the aid of synthetic pesticides or chemical fertilizers, and produced without the use of genetically modified organisms or chemical food additives. Many grocery stores now offer organic food sections where consumers can purchase non-GMO foods. The USDA is committed to helping organic food production thrive, and it provides an organic certification for farmers and ranchers who want to avoid synthetic materials in food and fiber production.10
How do GMOs and organic foods compare nutritionally? Several studies have been conducted in hopes of answering that question. To date, none have proved that organic foods are nutritionally superior to conventionally grown foods. (Several sources are cited in the Scientific American article Mythbusting 101: Organic Farming > Conventional Agriculture.)
Undoubtedly, the debate between GMOs and organic foods will continue. Fortunately, most consumers have choices when it comes to selecting the foods to put on their tables. Additionally, the economic impact of organic products promises to have a global impact (see information at https://www.ers.usda.gov/publications/pub-details/?pubid=45182).
Interest Approach – Engagement
- Use a computer and projection system to administer the GMOs & Organic Foods: Do You Know? Kahoot! quiz to students. (See teacher log-in instructions under Materials.) Instruct students to play the quiz on any smart device by logging into kahoot.it and following the prompts. The Kahoot Quiz Answer Key provides explanation of some answers.
- Lead a class discussion that involves creating a KWL chart on the topics of genetically modified foods and organic foods. Leave the chart in a place that can be accessed throughout the duration of this lesson.
Activity 1: Extracting Strawberry DNA
- Prepare the DNA extracting solution the day before the activity. Refer to the Materials list for measurements and instructions.
- Review and discuss the information provided in the Background Agricultural Connections section of the lesson with students. Pass out a Strawberry DNA Extraction Lab activity sheet to each student.
- Divide students into groups of three or four and provide each group with the following materials: Ziploc bag containing 3 strawberries and 3 tablespoons of DNA extracting solution, funnel, plastic cup, 2 squares of cheesecloth, graduated test tube, pipette, 3–4 microcentrifuge tubes (1 per student), and 3–4 pieces of yarn (1 piece per student).
- Guide students through the following instructions, which are also provided on their lab activity sheet:
- Collect your materials.
- Carefully remove most of the air from the Ziploc bag, and seal it well.
- Gently mash the strawberries through the bag. Be careful not to break the bag, but mix the strawberry mash thoroughly.
- Place the funnel in the plastic cup. It should sit on the rim of the cup.
- Place the two squares of cheesecloth into the funnel, forming a liner for straining.
- Carefully pour the strawberry mixture into the funnel, making sure to catch the solids with the cheesecloth. After filtering the mixture, remove the cheesecloth, and place it into the Ziploc bag for disposal.
- Add 5 ml of the filtered strawberry extract to the graduated test tube using the funnel. Hold the tube near the top so that the heat from your hand does not affect the extraction.
- Remove the funnel, and use the pipette to forcefully add 3 ml of the isopropyl or rubbing alcohol to the test tube. Take care not to tilt or tip the test tube; do not mix the two liquids.
- Observe the line between the strawberry mixture and the alcohol. You will notice a white, thread-like cloud appearing at this line. This is the strawberry DNA. The DNA will clump together and float to the top of the alcohol layer.
- Holding the tube still, observe the tubes of others around you. Do you notice any differences?
- Using the pipette, add some DNA strands and some of the alcohol in the test tube to each person’s microcentrifuge tube. Repeat steps 6 to 8 if necessary to collect enough DNA for everyone’s microcentrifuge tube.
- Close the cap of the microcentrifuge tube tightly around a piece of yarn and tie the ends of the yarn to make a necklace.
- Clean up! Dump the remaining strawberry solution where instructed, throw away the Ziploc bags, and collect the cups, test tubes, funnels, and pipettes to clean so they can be used again.
- Instruct students to complete their lab sheets by writing answers to the questions that follow the lab instructions.
- As a class, discuss students’ answers to questions #6 and #7.
- Show the videos How are GMOs Created? and What is a Genetically Modified Food?.
- Invite students to add to the KWL chart posted in the classroom.
Activity 2: The Debate
- Share with students the biographies of the debaters for the Intelligence2 debate Genetically Modify Food. (You may wish to edit these to save time.)
- Show two of the opening statements in the debate:
- Robert Fraley (pro) at cue 18:57:07 (7-minute duration)
- Margaret Mellon (con) at cue 19.05:08 (7-minute duration)
Instruct students to use the Decision Matrix to make notes on the pros and cons of producing and eating GMOs. (Alternatively, assign students to watch the entire debate as homework.)
- Following the video, instruct students to write their final decisions on their matrices and be prepared to share their reasons for making those specific decisions.
- As time allows, lead a class discussion and ask students to share their reasons for making their decisions, or hold a class debate.
- As homework, instruct students to write an opening statement—either pro or con—regarding “Genetically Modify Food.” Reading of the statement is limited to seven minutes.
Activity 3: GM Foods in the United States
- Share the article These Charts Show Every Genetically Modified Food People Already Eat in the U.S. with students (recommended to project the images).
- As GM foods are discussed, encourage students to add to the KWL chart created in the Interest Approach.
Some foods are voluntarily labeled by manufacturers as "non-GMO," but not all foods without a "non-GMO" label are GMOs. There are 10 crops in the United States that can be grown in GMO varieties. They include: corn, soybeans, cotton, potatoes, squash, papaya, canola, alfalfa, sugar beets, and apples.
Concept Elaboration and Evaluation
After conducting these activities, review and summarize the following key concepts:
- Production and distribution of food is affected by the relationships between geography, politics, and economics.
- Genetic modification is a form of biotechnology with important implications for agriculture.
- The production of genetically modified plants and animals for food has both benefits and costs.
- Agricultural practices have environmental consequences that can be alleviated by and/or caused by the development of new technologies.
We welcome your feedback! Please take a minute to tell us how to make this lesson better or to give us a few gold stars!
- Ask students to share their opening statements written in Activity 2.
- Using their decision matrices from Activity 2, have students argue the opposite side that they originally chose.
- Review with students the information found at Genetic Science Learning Center: Creation of an Insect-resistant Tomato Plant. Instruct students to write a response to the third prompt, “You are the leader of a developing nation...” under “What would you do in the following situations?” Students should include geographical, environmental, and economic factors in their responses.
- Share the article GMOs May Feed the World Using Fewer Pesticides with students to add an international perspective to the conversation about genetically modified foods.
- Watch The Journey to Harvest (3:01 mins) and learn about the 20-year journey of the Arctic Apple®. As a class discuss how arctic apples could decrease food waste and other consumer benefits such as convenient packaging and nutrition. Visit the Arctic Apple® website for more information.
- Define an "unintended consequence" with your students and brainstorm both positive and negative unintended consequences that could be associated with the use of GMOs. Assign students to read the article from NOVA, GMO Crops Have an Unintended Side-Effect: Protecting Non-GMOs.
Suggested Companion Resources
GM Leaf Test Kit (Activity)
GM Soybean Seed Kit (Kit)
Strawberry DNA Necklace (Kit)
Biotech Cheese Kit (Kit)
GMO Infographics (Poster, Map, Infographic)
Methods of Modification Podcasts (Multimedia)
The Facts and Knowledge of BT Corn (Multimedia)
The Life of a Seed- Jake, a GMO Seed (Multimedia)
Genetically Engineered Crops in the United States Report (Multimedia)
Genetically Engineered Crops Report (Multimedia)
How Are GMOs Created? (Multimedia)
What Can We Learn from Cuba's Organic Farms? video (Multimedia)
The Question of the Production of Genetically Modified Foods (Website)
Genetic Science Learning Center (Website)
GMO Answers (Website)
- USDA Animal and Plant Health Inspection Service
- United States Department of Agriculture
- Reuters, Genetic Science Literacy Project
- “Financial competitiveness of organic agriculture on a global scale,” Proceedings of the National Academy of Sciences
Doug Andersen (UT), Nancy Anderson (UT), Paul Gray (AR), Ken Keller (GA), Lisa Sanders (MN), Sharon Shelerud (MN), Allison Smith (UT), Kelly Swanson (MN)
DNA Extraction Activity used with permission from Debra Spielmaker, Utah State University
National Agriculture in the Classroom