Investigation: Does Your Saliva Contain DNA?
Extracting DNA from saliva is a fun and educational activity that offers hands-on learning and brings the microscopic world of genetics to life. You will engage in the scientific process of collecting a saliva sample and viewing strands of DNA that are within the cells of your mouth.
Materials Needed:
- Saliva collection tubes or containers
- Distilled water
- Table salt (sodium chloride)
- Clear dishwashing detergent
- Isopropyl alcohol
- Wooden sticks or coffee stirrers
- Clear plastic cups
- Graduated cylinder or test tube
- Funnel
- Ice-cold rubbing alcohol
- Paper towels
- Pipettes or droppers
Procedure:
-
Saliva Collection:
- Refrain from eating or drinking anything, except water, for at least 30 minutes before collecting saliva.
- Spit into a small cup or container, until there is enough saliva for the experiment (around 2-3 ml). Medicine cups work great and are easy to dispose of!
- Add a pinch of table salt to the saliva and mix well. This helps break down the proteins and release the DNA.
- Cell Lysis:
- Add a few drops of dishwashing detergent to the mixture. Gently swirl the cup to mix. The detergent helps break down the cell membranes and release the cellular contents, including DNA.
- Add a few drops of dishwashing detergent to the mixture. Gently swirl the cup to mix. The detergent helps break down the cell membranes and release the cellular contents, including DNA.
- Filtering:
- Place a funnel on top of another clear plastic graduated cylinder or test tube. Add a coffee filter to the funnel.
- Filter the saliva mixture through the funnel and coffee filter. Be patient, it may take a while for it to filter.
- Precipitation of DNA:
- Use a pipette to slowly drip cold alcohol over the top of the mixture. The DNA will rise to the surface!
- Use a pipette to slowly drip cold alcohol over the top of the mixture. The DNA will rise to the surface!
- DNA Collection:
- Use a coffee stirrer to carefully collect the visible DNA strands. Avoid disturbing the rest of the mixture.
- Place the collected DNA on a clean surface, such as a piece of paper or a microscope slide.
Other DNA Labs
Strawberry DNA Extraction - instructions for extracting DNA from a strawberry, very simple, works every time!
Investigation: DNA Extraction for AP Biology - students extract DNA from different samples and write a lab report; with Claim, Evidence and Reasoning
DNA Investigation with Strawberries (basic) - simplified version of DNA extraction lab for intro level, with minimal equipment