Biology: Patterns and Processes of Life


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  • Perfect bound, non-consumable
  • Over 70 labs sorted by chapter
  • Each lab begins with an Introduction and Background section explaining the purpose of the lab followed by a Materials list, Safety guidelines, Procedure steps and Discussion Questions
  • Data Tables and answers are provided in the Teacher's Notes
  • The style of labs runs the entire spectrum

Below is a sample lab from the Lab Manual.

11.3 DNA Extraction from Strawberries

Introduction and Background
DNA is found in all living things, so it should be possible to extract the DNA from cells or tissue. All we need to do is disrupt the cell’s plasma membrane and nuclear envelope, make the DNA clump together and voila, DNA extraction is possible. Plant material is easy to use and DNA extractions from onion, bananas or wheat germ are common classroom activities or demonstrations.

Plants used in agriculture and horticulture are often artificially selected for their large flowers and fruits. Strawberries are no exception. A reason for the size of today’s large supermarket strawberries is the octaploid nature of their cells. With eight sets of chromosomes, they have plenty of DNA for classroom extraction. Perhaps this helps compensate for their lack of flavor!


  • Ziploc baggies
  • Small (10 mL) graduated cylinders
  • Beakers or cups for straining
  • Cheesecloth
  • Test tubes and containers or racks to hold them
  • Wood splints or disposable inoculation loops

  • Strawberries
  • Extraction solution (10% shampoo and a dash of salt)
  • Ice cold ethanol (70% pharmacy ethanol will work)

Safety glasses should be worn. Other items like aprons or gloves are optional. No special disposal practices are required. At the end, baggies can be zipped and discarded, liquid material can be rinsed down the drain.

  1. Smash several strawberries in a Ziploc baggie for 1 minute.
  2. Add 10 mL extraction solution
  3. Smash solution/berry mix for an additional 1 minute
  4. Filter through cheesecloth
  5. Pour 2-3 mL of filtrate into a test tube
  6. Layer twice this volume with ice cold ethanol
  7. Stir gently with inoculation loop and spool DNA as it clumps at the EtOH/filtrate interface. Compare the amount of your extracted DNA with other groups’ DNA.

Discussion Questions
  1. Why is shampoo used in the extraction solution?
  2. Explain the role of salt in the extraction solution.
  3. Why is it necessary to use ice cold ethanol instead of room temperature EtOH? Would ice water have also worked? Explain your answers.
  4. Why might some groups get more DNA than others? Think of at least two reasons.