Monday, 16 June 2008

Science Lesson...

I decided to have some fun today. And just to prove that I'm a real Science teacher, I thought I'd share... There aren't many genetics experiments which can be carried out in school labs, but this is one which can even be done at home... Extracting DNA from kiwi fruit.

First, chop up one kiwi fruit. (Memo to self: peel the fruit first, numbskull!) Add 50 mls (approx) washing-up liquid, a tablespoon of salt and half a litre of warm water (not hot, or you'll denature the DNA!)

Stir, and leave for 20 minutes. Then put the mixture in the freezer for 10 minutes.

Take the mixture out of the freezer (it should be cold) and put it in a liquidiser: blend it for 10 seconds.

Filter the mixture using a coffee filter paper. This step is optional, but it means that the experiment works better.

Take about 10 ml of the filtrate and put it in a glass. Add a squirt of pineapple juice (yes, pineapple juice has protein-digesting enzymes in it... oh, and your flesh is made of protein, so go easy on the pina coladas!)

Carefully add ice-cold ethanol (vodka will do if you are trying this at home) down the side of the glass, so that the ethanol forms a clear layer on top of the filtrate.

Leave the glass to stand for five minutes.

You should see a white cloudy lump forming in the ethanol - voilà! You have extracted kiwi fruit DNA !

9 comments:

the mother of this lot said...

You do the experiment. I'll just sit here with an ethanol and tonic.

Mac McLernon said...

LOL !

Better still, why don't we let the kids do the experiment, and then we can both sit down with an ethanol and tonic (and easy on the tonic!!)

gemoftheocean said...

Have a contest for which kid can do the experiment the slowest. ;-D

Okay, once you GET the DNA ... what do you do with it?!

puellapaschalis said...

Ok, I have GOT to try this!

Why weren't you my science teacher Mac? I mean, mine were ok, but the most interesting thing I remember from four years of high school was dissecting a sheep's heart. All the cultures I ever tried to grow in a petri dish never, ever worked. DNA and kiwi fruit would have been so much more fun...

Londiniensis said...

Miss, Miss, If this is vodka flavoured with pulped kiwi fruit and pineapple juice, can we drink it and what does it taste like?

Mac McLernon said...

Tsk, tsk ! Londiniensis, you obviously were not paying attention when I gave the instruction to add 50 ml of washing-up liquid...

;-)

Mac McLernon said...

Karen you look at the DNA when you have obtained it, and bask in the secure knowledge that you have carried out an experiment which has no application in the real world whatsoever. Who cares? It's fun!

:-)

ashley said...

I've done this with strawberries before.
The end result is showing off that DNA looks like boogery slime. :)

MaggieClitheroe said...

Oh I love ashley's comment at the end, I was just getting all fired up to do some homeschooling science, but I think I'll just tell him to pick his nose instead, and that's wot dna looks like! lol!

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