DNA Extraction from Strawberries Lab

Overview

  • Grade Level: 9th Grade

  • Subject: Biology

  • Topic: DNA Extraction

  • Lab Type: Experimental

  • Duration: 30 minutes

  • Safety Level: Low

Learning Objective

  • Students will learn to extract and observe DNA from strawberries.

Materials Needed

  • 2 ripe strawberries

  • 1 cup of isopropyl alcohol (chilled)

  • 2 tablespoons of dish soap

  • 1 tablespoon of salt

  • 2 cups of water

  • Coffee filter or cheesecloth

  • Clear glass or plastic container

  • Pipette or dropper

  • Stirring stick or spoon

  • Labels and markers

Safety Precautions

  • Wear safety goggles to protect your eyes.

  • Handle isopropyl alcohol with care; avoid ingestion and skin contact.

  • Keep workspace clean and organized to avoid accidents.

  • Wash hands thoroughly after completing the lab.

Procedure

  1. Prepare the extraction solution by mixing water, dish soap, and salt in a container. (Teacher Tip: Explain the role of each component in the extraction process.)

  2. Remove the green leafy top from the strawberry and place it in a plastic bag. (Emphasize the need for proper handling of materials.)

  3. Use your fingers to mash the strawberry inside the bag for about 2 minutes to break down the cells. (Highlight the importance of cell breakdown in DNA extraction.)

  4. Add 2 tablespoons of the extraction solution into the bag and mix gently for one more minute. (Discuss the importance of each step to help students understand the process.)

  5. Pour the mixture through a coffee filter or cheesecloth into a clear container to separate the liquid from the solid parts. (Teacher Suggestion: Explain the filtration process and its significance.)

  6. Slowly add the chilled isopropyl alcohol to the container where the filtered liquid is collected. Pour it down the side to minimize mixing. (Instruct students on the method to prevent disrupting the extraction.)

  7. Observe the white strands forming between the layer of alcohol and the strawberry liquid; this is the DNA! (Encourage students to share their observations.)

Observations

  • Record the appearance of the mixture at each step.

  • Note the presence of white, stringy material that forms in the alcohol layer.

Questions

  • What does DNA look like after extraction?

  • Why do you think strawberry DNA is visible when mixed with alcohol?

  • How does the detergent help in extracting DNA?

  • What role does the salt play in the extraction process?

Assessment

  • Describe the process of DNA extraction in your own words.

  • Explain how the materials used contribute to the success of the experiment.

  • What challenges did you face during the experiment, and how did you overcome them?

Notes:

Ensure that students handle all materials safely and follow the procedure as outlined. Emphasize the importance of careful observations and detailed notes to support their learning.