DNA Extraction Lab
Perform a virtual fruit DNA extraction using strawberry, banana or kiwi and investigate how crushing, detergent, salt, filtration and cold alcohol help make DNA-containing material visible.
Strawberry is ready. Begin by crushing the fruit tissue.
Select Strawberry, Banana or Kiwi and begin with Step 1.
🎯 Aim
To demonstrate a simplified method of extracting DNA-containing material from fruit cells and understand the role of crushing, detergent, salt, filtration and alcohol.
🧰 Virtual Apparatus
Strawberry, banana or kiwi sample, crushing tool, detergent solution, salt, filter paper, funnel, test tube and alcohol.
📘 Principle
DNA is contained inside cells. Extraction involves breaking tissue, disrupting cellular membranes, separating larger debris and precipitating DNA-containing material using alcohol.
🧪 Function of Each Extraction Step
Breaks fruit tissue into smaller pieces and increases contact between cells and the extraction solution.
Helps disrupt lipid-rich cellular and nuclear membranes.
Salt ions can help reduce charge-related interactions and support aggregation during extraction.
DNA is poorly soluble in alcohol under suitable conditions, allowing DNA-rich material to precipitate.
📝 Procedure
- Select Strawberry, Banana or Kiwi.
- Crush the selected fruit tissue.
- Add detergent solution.
- Add salt.
- Filter the mixture.
- Collect the liquid filtrate.
- Carefully add alcohol.
- Observe the interface between the aqueous extract and alcohol.
- Look for whitish/stringy DNA-containing material.
- Record the observation.
📋 Observation Table
| Trial | Fruit | Crushed | Detergent | Salt | Filtered | Alcohol | Observation |
|---|---|---|---|---|---|---|---|
| Complete the experiment and press Record. | |||||||
🧠 DNA Extraction Challenge
🎓 Quick Viva
1. Why is the fruit crushed?
Crushing breaks the tissue into smaller pieces and increases contact between cells and the extraction solution.
2. Why is detergent used?
Detergent helps disrupt lipid-rich cellular and nuclear membranes.
3. Why is salt added?
Salt ions can help reduce charge-related interactions and assist DNA aggregation during extraction.
4. Why is filtration performed?
Filtration separates larger pieces of fruit tissue and debris from the liquid extract.
5. Why is alcohol added?
DNA has relatively low solubility in alcohol under suitable conditions, allowing DNA-containing material to precipitate.
6. Why is cold alcohol commonly used?
Cold alcohol is commonly used in classroom protocols because it can improve precipitation of DNA-rich material.
7. Can an individual DNA molecule be seen here?
No. Individual DNA molecules are far too small. The visible strands contain very large numbers of molecules aggregated together.
✅ Result
After crushing the fruit, disrupting cellular membranes, adding salt, filtering the mixture and adding alcohol, whitish/stringy DNA-containing precipitated material becomes visible.