Anthony Bertino, Lana Hays
1993 Woodrow Wilson Biology Institute


The purpose of this activity is to provide a format that can require students to better prepare for laboratory experiences by helping them to understand the procedures involved in advance of the lab time. This same format may be used for either data collecting or demonstration type lab experiences. It will avoid the necessity of the teacher having to explain each step of the lab that is already clearly written. It allows each student to demonstrate a little creativity as a series of left and right brained interactions lead to a clearer understanding of the procedures involved in a laboratory exercise. Simply put, the teacher will no longer have to explain the steps of a clearly written lab.


Grades 7-12, all ability groups


30 minutes preparation outside of class before the lab is to take place.


  • A colored-coded copy of the lab experience.
  • A copy of the cookbook translation page.


    The day before the laboratory experience:

    1. Provide each student with a copy of the lab experience on colored paper.

    2. Provide each student with a 'cookbook translator' sheet [your choice of color but different from the lab directions ('cookbook')].

    3. Assign the 'cookbook translator' to be completed for homework by each student prior to arrival at class on the day of the lab experience.

    4. As each student arrives at class, collect the 'cookbook' directions, leaving only the 'cookbook translator' in the hands of each student.

    5. Students may work in groups depending on the exercise but only the 'cookbook translators' (and each other) may be used for directions and completion of the lab.

    6. Each student is to complete the 'cookbook translator' for evaluation at the completion of the laboratory experience.

    NOTE: If a student arrives at lab without the 'cookbook translator' completed on the frontside, that student will not be admitted to the laboratory experience. The lab will instead be rescheduled at a later (often less convenient) time! It will not happen more than once! Colored paper readily identifies the 'cookbook' original and separates those who have done their preparation from those who have not. The 'cookbook translator' does not need to make sense to anyone but the student who has prepared it. It provides an excellent review later in the year and could easily become part of a student's portfolio.

    Using the following laboratory experience on DNA extraction, the principles of the 'cookbook translator' have been applied. The sketches were generated by Lana Hays, author of the extraction lab.

    The Rules:

    1. no words
    2. chemical symbols, numbers allowed
    3. number each procedure as it appears in the lab


    Don't forget your back side! Use it for a data collecting lab.

    Page 1

    The backside!

    Some terms:

    control group:
    the group used as a standard for comparison

    independent variable(s):
    the variable(s) manipulated or changed by the experimenter

    dependent variable(s):
    the variable(s) that responds and is measured

    all factors kept the same during the experiment

    Identify the following:

    1. the control -

    2. the independent variable-

    3. the dependent variable-

    4. the constants -

    Did the experiment work as expected?______________________

    Explain here:

    Please summarize your results here. If a graph or table is requested, please add it in the space below:

    Please restate the purpose of this lab experience as a question here.




    This lab is a relatively simple and inexpensive DNA extraction from bacteria. Although materials such as SDS and ethanol work best, common products like Woolite and isopropyl alcohol are adequate for the extraction. This lab will work even if some errors are made. The key is to have equal volumes of suspension/Woolite and alcohol.

    Target Age/Ability Group:

    Grade 7-12

    Student/Class Time:



  • Woolite - Dawn, Joy or any other dishwashing detergent could be used. SDS - sodium dodecyl sulfate actually works best.
  • Calibrated measuring device - graduated cylinder, pipette, medicine dropper or medicine cup.
  • Isopropyl alcohol - can be obtained from a pharmacy ranging in concentration from 91-100%. 95% ethanol actually works best.
  • Safety Precautions:

    All materials may be discarded down the sink.

    Material Preparation

    To prepare a lima bean suspension, simply add a handful of dry beans to a large beaker or quart jar and fill with tap water. Cover it loosely with Saran Wrap and let it sit at room temperature for about 3 days. Swirl it once or twice daily. The amount of time may vary depending on the room temperature. The solution (suspension of bacteria) will be very cloudy and it can then be drawn off for the DNA extraction.

    Teacher's Notes

    The bacteria associated with the lima beans are large bacteria that may also be used for serial dilutions, observations or staining.

    Student Copy -Lima Bean DNA Extraction Lab


  • Bacterial suspension from lima beans
  • ice bucket/ice
  • 15 ml culture tube
  • hot plate
  • Woolite
  • thermometer
  • 500 ml beaker or pan
  • glass stirring rod
  • graduated cylinder, pipette, or eyedropper
  • tape
  • 91% isopropyl alcohol
  • permanent marker
  • Procedure:

    1. Use tape or permanent marker to label your culture tube with your name.

    2. Add 5ml of bacteria suspension to your culture tube.

    3. Add 1ml of Woolite to the bacteria suspension. Cap the tube tightly and rotate it gently for 5 minutes. This should lyse (rupture) the cells and release DNA. You may notice that the suspension becomes thicker as the bacteria are lysed.

    4. Stand the tube for 30 minutes in a hot water bath preheated to 65-70 deg C and maintain the temperature. The 65-70 deg C range will denature (break apart) the protein once it is separated from the DNA. A temperature greater than 80 deg C will denature the DNA.

    5. While the tubes are in the water bath, aliquot (measure out) 6ml of isopropyl alcohol into another culture tube, cap it, and place it in the ice bucket until needed.

    6. Remove the test tube from the water bath. Allow it to cool to room temperature. If necessary, the lysate in this test tube may be refrigerated for up to one week, but it must be warmed to room temperature before using.

    7. Add the cold isopropyl alcohol to the culture tube by tipping the tube at an angle and allow the alcohol to flow down the side of the tube. If done carefully, it will prevent the two layers formed from mixing.

    8. Hold the tube at a 45 degree angle, place the stirring rod into the tube and slowly rotate it. DNA fibers should come out of the solution and attach to the glass rod. Continue the process until no more DNA comes out. The DNA is soluble in water and insoluble in alcohol. Thus it forms a precipitate in the alcohol.

    The 'cookbook' translation for the lab entitled


    The rules:

    1. no words
    2. chemical symbols, numbers allowed
    3. number each procedure as it appears in the lab


    Don't forget your back side! Use it for a data collecting lab.

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