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Extract DNA from a Pumpkin

Extract DNA from a pumpkin using household materials.

Materials

Instructions

  • Cut off a section of the pumpkin and clean off the “insides.” Cut the pumpkin into small chunks that will fit into the blender.
    You will see a milky layer form between the pumpkin water mixture and alcohol. This layer contains the strands of DNA that were released from the cells. What Is Happening. What Is Going On In This Activity Cellulose is found in the cell wall of every plant cell, including every cell in the pumpkin used in this activity. Cellulose is the substance that provides strength to the cell wall and helps with water absorption, which helps keep the plant hydrated. Cellulose is a complex carbohydrate that does not break down in water. By putting the pumpkin through the blender, we are breaking up the cellulose in the cell walls. Now, the cell membrane is the cell wall inside the cellulose. This cell membrane is made of lipids (fats) and proteins. Next, we need to understand more about detergent molecules. Detergent consists of long molecules, also called surfactants. Each of these long molecules has a head and a tail. The head is attracted to water; in other words, it is hydrophilic. The tail is attracted to dirt and grease, this attraction characteristic is called hydrophobic. So, when detergent is used to clean dishes, the hydrophobic end of the surfactant attaches to the grease on the dishes. The hydrophilic end attaches to the water. When we added the detergent to the pumpkin juice, the detergent attached to the lipds (fats) in the cell membrane. The hydrophilic end of the detergent molecule attached to the water. These actions cause the cell wall or membrane to rupture and the cell is disintegrated in a process called lysis. When we carefully added the layer of alcohol, the DNA that was in the cell does precipitates out because it does not dissolve in alcohol (This means DNA is not soluble in alcohol.), so the strands of DNA clump together and look milky in appearance.
  • Add 1/2 cup of water.
  • You want to blend it just enough to cut the pumpkin into small pieces but not liquefy it. We did about 5 pulses on our blender. When we over-processed the pumpkin, it may have obliterated the DNA, which may have been why our first batch didn't work.
  • If your blender is too full, carefully transfer the pumpkin to a bowl and add one tablespoon of salt.
  • Add 1/4 cup of the clear dishwashing liquid. Stir carefully with a spoon, but mix thoroughly.
  • Place the coffee filter securely into the funnel, and place the funnel securely over a glass beaker or cylinder or a drinking glass
  • Fill the funnel 2/3 of the way with the pumpkin mixture. Allow the pumpkin water to drain for 20 minutes or so. We made a makeshift funnel with another coffee filter and a small beaker, to help facilitate this step in the process.
  • When enough pumpkin water has drained, gather the 1/4 of isopropyl alcohol. Tilt the glass slightly and slowly put the alcohol into the glass down the tilted side of the glass. The goal is to form a layer of the alcohol on top of the pumpkin water. Gently place the glass flat on the work surface and wait.

Notes

  • Put the alcohol in the freezer for at least 2 hours. Alcohol does not freeze, so you cannot get the alcohol too cold.
  • We opted for clear dishwashing liquid without any strong scents. Below is a photo of the label from the dish soap we used
  • It takes a while for the liquid from the pureed pumpkin mixture to drain through the coffee filter. We set up two glasses with funnels and filters and a makeshift funnel (pictured below).
  • We used our Ninja instead of a full-sized blender.