The Arizona STEM Acceleration Project

Extracting DNA from Strawberries

Extracting DNA from Strawberries

A [9^th / 10^th ] Grade STEM Lesson

Ellyza Hardin

November 2023

Notes for Teachers

Context: This activity takes place in 2 hours.

- Students may work in small groups of 3-4.

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Preparation:

1. Chill the isopropyl alcohol in the freezer.
2. Cut the strawberries into small pieces.
3. Prepare a mixture of liquid dish soap, table salt, and meat tenderizer/pineapple juice. This mixture will serve as the extraction solution.

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List of Materials

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1. Fresh strawberries (one per student or group)
2. Ziplock bags (1 per student or group)
3. Liquid dish soap
4. Table salt
5. Meat tenderizer or pineapple juice (contains enzymes that break down cell walls)
6. Isopropyl alcohol (chilled in a freezer)
7. Coffee filters or cheesecloth
8. Small plastic cups or test tubes
9. Wooden sticks or coffee stirrers
10. Ice or ice packs

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Arizona Science Standards

Plus HS+B.L1U1.4 Develop and use models to explain the interdependency and interactions between cellular organelles

Essential HS.L3U1.25 Obtain, evaluate, and communicate information about the causes and implications of DNA mutation.

Plus HS+B.L3U1.11 Construct an explanation for how the structure of DNA and RNA determine the structure of proteins that perform essential life functions. 

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ELA Standards

9-10.SL1

Speaking and Listening Standard

Comprehension and Collaboration

Initiate and participate effectively in a range of collaborative discussions (one-on- one, in groups, and teacher-led) with diverse partners on grades 9–10 topics, texts, and issues, building on others' ideas and expressing their own clearly and persuasively.

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Objective(s):

Today…

• Students will learn the simple method to extract DNA and why each step is necessary due to the complex organization of DNA in cells.
• Students will be able to carry out a simple DNA extraction experiment using strawberries.
• Students will learn why it is important for scientists to extract DNA from organisms.
• Students can explain how all living things contain DNA.

Agenda (110 minutes)

Day 1

-Introduction (10 minutes)

Students will be in their group…

-Procedure/ Experiment/ Observation (40 minutes)

-Cleaning Up the area (5minutes)

Day 2

Students will be in their group…

-Group Discussion (15 minutes)

-Completing of Individual Worksheet (15 minutes)

-Whole group discussion (10mins)

-Assessment

Intro/Driving Question/Opening

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Begin by discussing the importance of DNA and its role in living organisms. Briefly explain the structure of DNA and its presence in the cells of all living things.

Hands-on Activity Instructions

• In a group with 2-3 students, they will follow this procedure.

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Hands-on Activity Instructions

• In a group with 2-3 students, they will follow this procedure.

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Hands-on Activity Instructions

• In a group with 2-3 students, they will follow this procedure.

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Hands-on Activity Instructions

• In a group with 2-3 students, they will follow this procedure.

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Start of Day 2…

Group Discussion

Observations:

-Ask students to describe what they see.

-Discuss the appearance of DNA and its physical properties.

Explanation:

-Explain the science behind each step of the extraction process, emphasizing the role of the extraction solution in breaking down cell membranes and the precipitation of DNA in the alcohol layer.

Conclusion (10 minutes): �

• Wrap up the lesson by summarizing the key points:
• DNA extraction involves breaking down cell walls, separating cellular components, and isolating DNA.
• Students have successfully extracted DNA from strawberries and observed its physical properties.
• Discuss real-world applications of DNA extraction, such as forensic science, genetic research, and medical diagnostics.

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Assessment

Complete the individual worksheet with observation, conclusion, and analysis.

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Please see the attached file:

StrawberryDNAExtra.pdf

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Differentiation

Misunderstanding: Lack of Observation Skills

• Guided Observation
• Provide a checklist or guide for students to follow when observing the interface between the alcohol and strawberry mixture.
• Encourage students to work in pairs or small groups, fostering collaboration and discussion during the observation process.
• Discuss the expected appearance of DNA strands and address any discrepancies in observations.

Real-World Applications Discussion

• Facilitate a class discussion on real-world applications of DNA extraction.
• Connect the experiment to fields such as forensics, genetics, and medicine, emphasizing the practical significance of the skills learned.
• Invite guest speakers or arrange a field trip to a laboratory where DNA extraction is routinely performed.

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Remediation

Extension/Enrichment

• Comparative DNA Extraction:
• Extend the experiment by extracting DNA from different fruits (e.g., bananas, kiwis, or oranges) and compare the yield, appearance, and difficulty of extraction.
• Discuss the variations in DNA content among different fruits and the factors that contribute to these differences.
• Biotechnology and Genetic Engineering:
• Explore the applications of DNA extraction in biotechnology and genetic engineering.
• Discuss genetically modified organisms (GMOs) and how scientists manipulate DNA for beneficial purposes.
• Encourage students to research and present a case study on a specific application of genetic engineering.

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