DNA Extraction

By : Harley, Richard, and Shanlie

How does changing the enzyme from meat tenderizer to pineapple juice affect the amount of DNA?


Step One: Get materials

Step Two: Blend peas and make sure to use the same amount of water and salt

Step Three: Strain and place in cup

Step Four: Add a few drops of soap (make sure its the same amount for each cup) let sit for 5-10 min

Step Five: Fill test tube 1/3 full, add enzyme, stir softly

Step Six: Add alcohol slowly, tilting the test tube

Step Seven: Observe, compare and record your findings. Use drawings, pictures, and data table.

This procedure helped us answer the investigation question because it showed the difference in the amounts of DNA with the two different enzymes.


Shanlie's prediction: The DNA will not form as well because pineapple juice is not as good of an enzyme.

Harley's prediction: There will not be as buch DNA because pineapple juice does not break down proteins as well.

Richard's prediction: The meat tenderizer would have more DNA than pineapple juice because the meat tenderizer breaks down proteins well.

These predictions were wrong, as the amounts of DNA were the same. The reason the amounts were the same is because pineapple juice and meat tenderizer are both enzymes that separate the proteins from the DNA.


Controlled variable: pea mixture with meat tenderizer enzyme

Uncontrolled variable: pea mixture with pineapple juice enzyme

The amount of DNA in both pea samples (one with meat tenderizer and one with pineapple juice for enzyme) was about the same. When we used meat tenderizer, the DNA was very stringy. When we used pineapple juice, the DNA was in big chunks.

Possible Errors

Possible errors during this extraction include not getting the same amount of peas, soap, enzyme, and alcohol in each test. Ways to improve next time would be to measure everything carefully.

Future investigations

Ideas for future investigations include:

  • Try the same investigation again
  • More trials
  • Precise measuring
  • Larger amount of pea mixture
  • Different organism (other than peas)
  • Try a different enzyme (contact solution) and compare to pineapple juice and meat tenderizer