For those who like to do science stuff with their kids--here's a cool at-home activity

[Lyric]

It's something we did in my Bio Lab class this past semester, and it doesn't require any scary, unfamiliar chemicals. It's great for homeschoolers as well. So long as you keep everything nice and cold and handle the liquids gently, it's hard to mess this one up. Use substitute containers if you need to--these are just what *we* used.

At-Home Banana DNA Extraction

Note: the DNA extracted here still contains some other protein; greater refinement would be necessary to extract 100% pure DNA

Activity Materials:

Two jars or beakers that are roughly 250ml each
Liquid dish soap (clear is best, but any will work)
1/2 a banana, sliced
Mortar and Pestle
Plain table salt (not iodized)
One coffee filter
A rubber band
A clear glass test tube
ICE COLD grain alcohol (ethanol) Put it in the freezer well beforehand, and keep it ice cold during the activity. This is important!
A long wooden toothpick
A bowl of ice that's big enough to hold your mortar bowl.

Activity Instructions:

Put the mortar into the ice and keep it there--it needs to stay very cold. Don't let the ice get into the bowl part.

Make a weak detergent solution in one of your 250ml beakers--about 9 parts water to one part detergent.

Put the banana slices in the mortar.

Add the 10% detergent solution to cover the banana slices.

Add a pinch of salt.

Grind the banana in the soap solution with the pestle until totally smooth. Do this GENTLY; you don't want to make it bubbly or foamy. Keep the bottom of the mortar on ice while grinding. This part takes a while.

Put the coffee filter on top of the other 250ml beaker and press down gently until there's an indentation big enough to hold the banana pulp mixture, then fasten it with the rubber band.

Pour the mashed banana mixture onto the coffee filter and put it into the fridge to filter through--about 5-10 minutes.
Remove the coffee filter and throw away the leftover banana solids.

Pour enough of the filtered banana liquid into the glass test tube to fill it about 2 cm high.

Add twice that amount of cold grain alcohol; pour it slowly and carefully down the side of the tube, so as not to mix the two layers. You want the banana liquid to be the bottom layer with the alcohol floating on top of it.

Almost immediately, a white, cloudy, stringy substance will appear between the layers--this is your DNA. To extract it, twist the wooden stick around it and pull it out.

You can touch it and examine it, but don't eat it or put it in your mouth. I don't imagine that the mixture of soap/salt/alcohol would taste very good. ;)

We did this in Lab, and also at home with OktoberKid because it was pretty interesting. If you don't have bananas, other likely candidates are strawberry slices, fresh peach slices, and/or RAW wheat germ after it soaks in the soap mixture for a while and gets mushy enough to grind. Don't use anything cooked, as cooking destroys DNA. Basically, anything raw and mushy enough to grind smooth is fair game.

[The Velveteen Ocelot]

1. Cool!

Could you do this with raw meat? Collect chicken DNA, for example?

[Lyric]

2. You probably could if you used a blender or a food processor

to turn it into mush first.

:hi:

[fortyfeetunder]

3. Where could I find ethyl alcohol?

Could I use 151 rum instead?

[Lyric]

6. Ethanol is just pure grain alcohol--it's sold in some states

under the brand name "Everclear."

I'm not sure if Bacardi 151 would work or not, but it couldn't hurt to try. :)

[FloridaJudy]

4. Beats the ones my son and my ex used to do

BTW, eggs in their shells really will explode if you microwave them. And centripetal force will keep the water in the bucket if you spin real fast...at least until the handle breaks.

[Lyric]

7. ...

:rofl:

Yes, this one is certainly a lot less messy! :P

(I did not know the egg thing, but thanks for the heads-up!)

Try putting a Mentos candy into a bottle of Coke and see what happens. Warning: do it outside, lol.

[FloridaJudy]

8. *I* did that one with my son

We used the parking lot.

[Tikki]

5. Thank you...exactly the kind of important fun...

and learning activity we enjoy sharing with our grandson.

The Tikkis

[formercia]

9. I don't know if I should go there

Now I know how to find the banana perp.