Extraction of Strawberry DNA

Introduction

  Today, my lab group and I performed DNA extraction on a strawberry. There were multiple steps to the extraction, but the steps were rather simple. This blog will include the steps of the extraction, why they were performed, and pictures of the lab.

Steps and Pictures

1. Make DNA extraction buffer
• 5 mL dish water detergent or shampoo
• Importance: Dish water detergent and shampoo both contain ingredients that break down the membranes within a cell, releasing DNA. The main ingredient in detergent and shampoo is sodiumdodecyl sulfate (SDS). SDS pokes holes in the cell membranes, weakening them, and then they are further broken down by a blender or crushed with hands. 
• 0.75 g of salt
• Importance: Once the DNA molecules are released they move around. By using salt in the extraction buffer, DNA molecules stick together. Salt also plays a role in DNA extraction by removing histone proteins that hold DNA molecules together.
• 45 ml of water
• Importance: Water is used in the extraction buffer to allow different substances to move around. Water is useful in a large variety of situations.
• Importance of DNA extraction buffer
• The DNA extraction buffer, along with hand grinding, breaks open the cells in a strawberry and releases DNA. Without this important buffer, the DNA would stay in the cells and wouldn't be visible.
• Picture (ingredients of DNA extraction buffer)
• 
• Salt on the left, detergent in the middle, water on the right 
2. Clean the strawberry, combine it with the extraction buffer, and crush the combination with your fingers. 
• Cleaning the strawberry + removing sepals
• Importance: Cleaning the strawberry is importance in order to make sure no unwanted materials are involved in the experiment. This can distort the data and result in the absence of DNA. You want to remove the sepals because they can get in the way and affect the data the same way that a dirty strawberry can.
• Combining the strawberry with extraction buffer
• Importance: You want to combine the strawberry and extraction buffer in a plastic bag so that the extraction buffer can perform its function. If you didn't mix the two, the DNA would remain in the strawberry cells.  
• Crushing the contents of the plastic bag
• Importance: The detergent or shampoo in the DNA extraction buffer poked holes in the cell and nuclear membrane. This weakened the membranes, but it wasn't enough to release DNA. By crushing the strawberry with your hands and exposing it to the DNA extraction buffer, more DNA can be obtained. Make sure not to crush too hard because DNA will degrade. 
• Picture of strawberry before combination with extraction buffer (ezwebrus.com)

• Picture of strawberry after combination with DNA extraction buffer



3. Use a filter, gauze, and test tube to filter the mixture
• Importance of filtering
• Filtering is an important process in DNA extraction. The gauze collects all strawberry cell debris and only allows the liquid solution to pass into the test tube. Because strawberry DNA dissolves into the DNA extraction buffer, the DNA can pass through the gauze into the test tube. Without filtering, the test tube would contain all parts of a cell, not just the DNA
• Picture of filtration process (i.ytimg.com)

• Picture of mixture after filtration

4. Add alcohol and use a wooden skewer to twirl the solution
• Importance of adding alcohol and mixing
• Because DNA is insoluble in alcohol, it precipitates. Alcohol allows the DNA to separate from the other ingredients used in the DNA extraction buffer. This splits the test tube into two layers; the top layer contains alcohol and DNA, and the bottom layer contains the junk ingredients from the extraction buffer. It is important to twirl the solution so the DNA comes together and is more visible. 
• Picture of test tube after adding alcohol

• Picture of DNA present in top layer of test tube after swirling





• Picture of DNA is a separate test tube



• Group Picture!!

Conclusion

  I found this experiment to be easier than I first thought and very fun. I never knew that DNA could be extracted in such a simple process that only requires household materials. Overall, my group and I received great DNA presence and we all had a great time. Extracting and observing the code of life is definitely an experiment worth conducting.