Australia's Science Forum

Welcome back to all
I am looking for simple DNA pracs. for Year 10. I'm sure all those brains out there(which means all Lab. Techs.!!) will have some tried and true experiments. I look forward to all your replies!!!!
Ta
Mother

Mother,

A modified extraction prac with strawberries. Can use Kiwi fruit as alternative.

Materials:
•1 heavy duty zip-lock bag
•Cheesecloth or 'Chux' wash cloth
•Wooden coffee stirrer
•Funnel
•Test tube
•1 strawberry (cut into quaters and frozen/defrosted to aid mushing)

Reagents:
•DNA extraction buffer
(50 ml liquid dishwashing detergent, 15 g NaCl and 950 ml water)
•Ice-cold 95% ethanol

Procedure:
1.Place one strawberry in a zip lock bag.
2.Smash strawberry with fist for 2 minutes.
3.Add 10 ml extraction buffer to the bag.
4.Mush again for one minute.
5.Filter through cheesecloth into test tube.
7.Slowly pour the ice-cold alcohol down the side fo the test tube. (creating a lower of ethanol on top)
8.At the interface, you will see the DNA precipitate out of solution. You may spool the DNA on your glass rod or pipette tip.


Hope this is what you are looking for.

Regards
Michelle

If you go to the Children's Medical Research Institute web site, http://www.cmri.com.au, there is a DIY DNA Extraction recipe, it is quite good as it has a print out which also contains questions for the students. The DNA is extracted from onion and works quite well. Follow the link to community outreach then to educational resources, there are other good DNA/genetics resources there also

This is the prac we use with great success. You can use onion instead of the banana. though for a class one banana is more that enough.


DNA extraction procedure:

1. In a blender, mix a ratio of one banana per one cup (250ml) of distilled water.
Blend for 15-20 seconds, until the solution is a mixture.
2. In one 5 oz cup, make a solution consisting of 1 teaspoon of shampoo and two
pinches of salt. Add 20 ml (4 teaspoons) of distilled water or until the cup is 1/3 full.
Dissolve the salt and shampoo by stirring slowly with the plastic spoon to avoid
foaming.
3. To the solution you made in step 2, add three heaping teaspoons of the banana
mixture from step 1. Mix the solution with the spoon for 5-10 minutes.
(The detergent dissolves the lipids that hold the cell membranes together, which
releases the DNA into the solution. The detergent causes lipids and proteins to
precipitate out of the solution, leaving the DNA. The salt enables the DNA strands to
come together.)
4. Place a #2 cone coffee filter inside a second 5 oz cup. Fold the coffee filter edge
around the cup so that the filter does not touch the bottom of the cup.
5. Filter the mixture by pouring it into the filter and letting the solution drain for
several minutes until there is approximately 5 ml (covers the bottom of the cup).
6. Obtain 20 ml of cold alcohol in a 50 ml tube.
7. Fill the plastic pipette with the filtered banana solution 2-3 times and add it to the
alcohol.
(DNA is not soluble in alcohol. When alcohol is added to the mixture, the
components of the mixture, except for DNA, stay in solution while the DNA
precipitates out into the alcohol layer.)
8. Let the solution sit for 2- 3 minutes without disturbing it, then gently invert the
tube several times. It is important not to shake the tube. You can watch the white
DNA precipitate out into the alcohol. When good results are obtained, there will be
enough DNA to spool on to a rod or a plastic loop. DNA has the appearance of
white, stringy mucus.

Hope this of some assistance

Many thanks everyone, great stuff!!! Will pass info. to teachers.
Pilar, I was unable to connect to the website you gave me.Bit of a shame really.
Take care all
Mother

Mother wrote:Many thanks everyone, great stuff!!! Will pass info. to teachers.
Pilar, I was unable to connect to the website you gave me.Bit of a shame really.
Take care all
Mother

That reason you couldn't connect was that the comma after the web address was also part of the link so the correct link is http://www.cmri.com.au/


Andrew

Hi mother,

We use the split peas dna that I found on http://learn.genetics.utah.edu/units/ac ... extration/

It works really well
Julz

Estelle,
This may be the thread you are looking for. It has some links for DNA extraction.
Rosalie

Here's the kiwi fruit one we use. It's quick to do, and works well.

Have just tried the extraction of DNA from strawberries with a great result (thought I had better try it first as we have never done this before). Much easier and cheaper and more impressive than the cheek cells extraction that used to be done with swishing gatorade. The recipe uses cold methylated spirits instead of isopropyl alcohol. HOD and Yr 10 teacher very excited at what I showed them. I love my job

Hey guys,

I just put together this fantastic DNA prac using gel electrophoresis, and the dyes from Southern Bio. Fairly cheap, using wow factor equipment, and (since I wrote the prac sheet) also funny and scandalous - as all good paternity pracs are. I've only included the front page and a photo of the results, because all the rest was just instructions on using micro-pipettes & electrophoresis chambers etc. However, if you'd like to see it all just PM me.

I like that paternity prac!

Love this site. Just got a request for strawberry ext. for DNA testing, bu t"sorry I don't know the method".
I just type in DNA in search window and walla, here it is.
Thanks, guys.
Lada

We just found that FROZEN strawberries and raspberries work really well, after thawing. Blueberries do not.
So keep a packet of the frozen fruit in freezer for those times when a teacher asks fr this immediately or the fresh fruit is too expensive

Great Idea Sunray

The teacher and his class did the pea DNA extraction and I did the banana one, mine worked more quickly and we got a great microscope slide from it. And mine smelt better. I printed it from chemtalk, so thanks guys! The pea one worked but was more involved and as said, not as easy to get a good slide from.

We tried lots of diffrent fruits the only one that did not work as well was grapes

In the interest of reducing plastic waste, has anyone tried the reusable zip lock bags for DNA extraction? I imagine that because they are a better quality plastic, the likelihood of breakages (loss of contents, starting again...) would be drastically reduced and actually make them worth the money and time to clean them. We are only a small school so I would only have to wash less than 20 (and they are dishwasher safe) for the whole year group if they worked in groups of 2 or 3.

We did Rosalie , but maybe our kids were too aggressive as we only got one reuse out of them before they started blowing out at the edges . In the end , Head Teacher said not to reuse them .

I wash and reuse zip lock bags all the time. Eventually they do have to go in the bin, sadly. Fortunately there are now some excellent compostable bags available. (Thankfully, my head teacher would never instruct me to not reuse something.)