DNA Isolation Extraction from Fresh Strawberries
A challenging, hands-on discovery and STEM project designed for curious young minds aged 10 to 14.
Materials Needed
- • Ripe fresh strawberries (3 units)
- • Liquid dish soap (1 tablespoon)
- • Table salt (1/2 teaspoon)
- • 91% isopropyl rubbing alcohol (freezer chilled) (1/2 cup)
- • Paper coffee filter and small funnel (1 set)
- • Clear glass tumbler and wooden skewer (1 set)
Pro Tips
- → Chill the rubbing alcohol in the freezer for at least 30 minutes before starting; ice-cold alcohol forces DNA strands out of solution much faster.
- → Strawberries are octoploid (meaning they carry eight copies of each chromosome), providing high yields of visible genetic material.
- → Pour the cold alcohol very slowly down the side of the tilted glass to form a separate layer floating on top of the fruit extract.
Safety First
Keep cold isopropyl alcohol away from heat; wear safety glasses. Do not ingest the final extract.
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Step-by-Step Instructions
Step 1
Mix 1/3 cup of water, 1 tablespoon of liquid dish soap, and 1/2 teaspoon of salt in a glass to prepare the cell-lysis buffer.
Step 2
Place 3 hulled strawberries in a zip-lock bag, add 3 tablespoons of lysis buffer, and mash thoroughly with fingers for 3 minutes.
Step 3
Filter the strawberry mush through a coffee filter resting in a glass tumbler to collect the clear reddish liquid.
Step 4
Slowly drizzle ice-cold isopropyl alcohol down the inside glass wall, and watch milky-white mucous strands of real DNA precipitate and spool onto a wooden stick.