National Agricultural Literacy Curriculum Matrix
DNA: Expressions in Agriculture
6 - 8
Two 45-minute sessions
This lesson centers around the activity of extracting DNA from a strawberry while highlighting careers in biotechnology and agriculture.
- Strawberry DNA Extraction Lab activity sheet, 1 per student
- Frozen strawberries, 3 per group
- Ziploc sandwich bags, 1 per group
- DNA extracting solution
- Make one day ahead so there are no bubbles in the 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
- Make one day ahead so there are no bubbles in the solution. In a gallon container mix:
- 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
- Biotechnology WebQuest activity sheet, 1 per student
*These items are included in the Strawberry DNA Necklace Kit, which is available for purchase.
Essential Files (maps, charts, pictures, or documents)
- Strawberry Varieties Image
- Strawberry DNA Extraction Lab Activity Sheet
- Biotechnology Webquest Activity Sheet
deoxyribonucleic acid (DNA): the heredity material in humans and almost all other organisms; similar to a “blueprint” of guidelines that a living organism must follow to exist and remain functional
genetic engineering: the process of manually adding DNA to an organism with the goal of adding one or more new traits not already found in that organism
genetically modified organism (GMO): any organism developed through a process in which a copy of a desired gene or section of genetic material from one organism is placed in another organism
Did you know? (Ag Facts)
- In 2013 about half of the total land used to grow crops in the United States was planted with genetically engineered crops.1
- Corn, cotton, and soybeans make up the majority of the genetically engineered crops planted in the United States.1
- More than 90% of the soybeans planted in the United States in 2013 were genetically engineered.1
Background Agricultural Connections
Interest Approach – Engagement
- Tell your students that you are thinking of a specific food, you are going to give them a list of clues, and you want them to guess which food you are thinking of. Ask students to raise their hands when they think they know the answer.
- This food comes from a perennial plant.
- In the United States, California grows the most of this food.
- This food is usually red but can also be yellow or white.
- This food has seeds on the outside.
- This food is a fruit.
- This fruit provides vitamin C to our diet.
- What is this fruit? Strawberries!
- Display the image below of various types of strawberries. Ask your students to list the similarities and differences they see among the pictures. Help students recognize that various colors, sizes, and shapes of strawberries exist. Strawberries are usually red, but they can also be white and yellow. Strawberries can also be small or large and oblong or round.
- Point out to the students that while these strawberries have different characteristics, they are all still strawberries. Ask the students, "What makes each of these strawberries different?" Provide further guiding questions and draw on students' prior knowledge of genetics and traits to help them recognize that the DNA in each of these strawberries is slightly different, leading to variation in characteristics.
- Explain that strawberry farmers and plant breeders work together to create varieties of strawberries that meet our needs.
Activity 1: Strawberry DNA Extraction
- Prepare the DNA extracting solution the day before the activity.
- Review and discuss the information provided in the Background 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, test tube, 3–4 microcentrifuge tubes (1 per student), and 3-4 pieces of yarn (1 per student).
- Guide students through the following instructions, which are also provided on their lab activity sheets:
- 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.
Activity 2: Careers in Biotechnology
- Provide each student with the Biotechnology WebQuest activity sheet, and instruct them to answer the questions on a separate sheet of paper.
- Review the students’ responses to the activity sheet.
- Ask students what kinds of careers in biotechnology would rely on DNA extraction. Guide the conversation so that students make a connection between the DNA they have extracted and the scientists who rely on similar methods to research and create genetically modified organisms (GMOs).
- Ask students about some of the pros and cons of biotechnology.
- List careers that would use biotechnology tools and information.
Concept Elaboration and Evaluation
After finishing the activities, review the following key concepts:
- Like all living things, every plant and animal used in agriculture has DNA.
- The process of DNA extraction is an important component of agricultural biotechnology, allowing plant and animal breeders to more accurately select for desirable traits and allowing scientists to genetically engineer organisms for agricultural use.
- There are a wide variety of agricultural career opportunities in biotechnology.
Watch the America's Heartland episode, Sweet Sweet Strawberries. This 5-minute video highlights strawberry production at a California farm, describes how strawberries are selectively bred for specific traits, and explains how strawberries are packaged for shipping all over the United States.
Suggested Companion Resources
- How to Extract DNA from Anything Living (Activity)
- Career Trek Game (Kit)
- Strawberry DNA Necklace (Kit)
- Crop Modification Techniques (Poster, Map, Infographic)
- Animal Biotechnology video (Multimedia)
- Careers in Agriculture Videos (Multimedia)
- Crop Genetic Engineering Simulation (Multimedia)
- Genetically Engineered Crops Report (Multimedia)
- How Are GMOs Created? (Multimedia)
- Natural GMO? Sweet Potato Genetically Modified 8,000 Years Ago (Multimedia)
- You're Hired! (Multimedia)
- Biotech in Focus (Booklets & Readers)
- Garden Genetics: Teaching With Edible Plants (Teacher Reference)
- 23andMe (Website)
- Agricultural Biotechnology Questions and Answers (Website)
- DNA Learning Center (Website)
- Feed, Nourish, Thrive (Careers Website) (Website)
- GMO Answers (Website)
- Genetic Science Learning Center (Website)
- Journey of a Gene (Website)
- The Question of the Production of Genetically Modified Foods (Website)
Agricultural Literacy Outcomes
Science, Technology, Engineering & Math
- Identify science careers related to both producers and consumers of agricultural products (T4.6-8.g)
- Provide examples of science and technology used in agricultural systems (e.g., GPS, artificial insemination, biotechnology, soil testing, ethanol production, etc.); explain how they meet our basic needs, and detail their social, economic, and environmental impacts (T4.6-8.i)
Education Content Standards
Biotechnology Systems Career Pathway
BS.03.04Apply biotechnology principles, techniques and processes to enhance plant and animal care and production (e.g., selective breeding, pharmaceuticals, biodiversity, etc.).
Career Ready Practices
CRP.10.1Identify career opportunities within a career cluster that match personal interests, talents, goals and preferences.
NCSS 8: Science, Technology, and Society
Objective 2Society often turns to science and technology to solve problems.
Objective 4Science and technology have had both positive and negative impacts upon individuals, societies, and the environment in the past and present.
Objective 8Science and technology sometimes create ethical issues that test our standards and values.
Common Core Connections
Reading: Anchor Standards
CCSS.ELA-LITERACY.CCRA.R.1Read closely to determine what the text says explicitly and to make logical inferences from it; cite specific textual evidence when writing or speaking to support conclusions drawn from the text.
CCSS.ELA-LITERACY.CCRA.R.10Read and comprehend complex literary and informational texts independently and proficiently.