Biologia

biology experimenThis is a simple, effective protocol for spooling DNA. Ripe strawberries are an excellent source for extracting DNA because they are easy to pulverize and contain enzymes calledpectinases and celluloses that help to break down cell walls. And most important, strawberries have eight copies of each chromosome (they are octoploid), so there is a lot of DNA to isolate.
• 100 ml(3/8 cup) shampoo (without conditioner) or 50 ml dishwasher detergent
• 15 grams sodium chloride (2 teaspoons)
• Water to 1 liter
• 1-3 strawberries (about the volume of a golf ball). Frozenstrawberries should be thawed at room temperature.
• 10 ml DNA Extraction Buffer (soapy salty water)
• About 20 ml ice cold 91% or 100% isopropyl alcohol
• 1 Ziploc bag
• 1 clear test tube
• 1funnel lined with a moistened paper towel
• 1 coffee stirrer or transfer pipette
1. Remove the green sepals from the strawberries.
2. Place strawberries into a Ziploc bag and seal shut.
3. Squishfor a few minutes to completely squash the fruit.
4. Add 10 ml DNA Extraction Buffer (soapy salty water) and squish for a few more minutes. Try not to make a lot of soap bubbles.
5. Filterthrough a moistened paper towel set in a funnel, and collect the liquid in a clear tube. Do not squeeze the paper towel. Collect about 3 ml liquid.
6. Add 2 volumes ice cold isopropyl alcohol to thestrawberry liquid in the tube. Pour the isopropyl alcohol carefully down the side of the tube so that it forms a separate layer on top of the strawberry liquid.
7. Watch for about a minute. What do yousee? You should see a white fluffy cloud at the interface between the two liquids. That’s DNA!
8. Spin and stir the coffee stirrer or transfer pipette in the tangle of DNA, wrapping the DNA aroundthe stirrer.
9. Pull out the stirrer and transfer the DNA to a piece of saran wrap or clean tube. The fibers are thousands and millions of DNA strands.
10. To view in a microscope, put the glob on...