Grade 8 Science - Banana DNA Extraction Lab Preparation - NOT testable material

Have a read through the following instructions, and click on the links for additional references. These steps are...simplified...compared to the one we will actually do in class. Single periods will be used to prepare for the Lab, and doubles to run the lab itself.

Terminology (due during the single period, where we review the procedure - and not part of the test these are actually all mixture terms...):

Precipitate (and not in the context of precipitation)
Filtrate

Preparation questions (also not required for the test, but necessary for the lab):

What is distilled water? How do we make it? (http://www.wikihow.com/Make-Distilled-Water)

Why is it important to mash the bananas?

Why does the alcohol float on the water?

EDTA is a key ingredient in the soap used in this experiment. What does it stand for?


http://www.null-hypothesis.co.uk/science/interactive/item/banana_DNA_extraction_kids_experiments

WHAT TO DO:
1. Dissolve about 1 gram of salt in 100 millilitres (ml) of water.
In terms of safety, there's actually no reason to wear latex gloves to dissolve salt in water. We just like wearing them.  There's also no need to do this in a lab, but they wouldn't let us out.
2. Mash up about ½ banana (or about ½ cuppeas) in the salt water to make a banana soup. Be sure it’s mashed up really well.
Mashing up the banana helps to break down the cell walls and will make DNA easier to extract. Salt helps DNA solidify later in the experiment.



3. Pour banana soup through a coffee filter into a new clear plastic cup. You'll only need about 5-10 ml for the rest of the experiment. Toss out coffee filter with banana bits (or save for banana bread!)Cells need to be nice and mashed up before you can extract DNA. This is why we need to filter the clumpy bits through the coffee filter.


4. Add a few drops of washing up liquid to your banana soup. Swirl the mixture but do not shake - no bubbles!! (You can also do this with jazz hands).Washing up liquid is made of grease, which is very similar to cell membranes. The grease will penetrate the membranes and break them up, allowing the DNA to escape from the nucleus.



5. Let mixture sit for about 5-10 minutes.

6. Add about 1-2 millilitres of pineapple juice. Stir GENTLY!
When you broke open the cell membrane with the detergent, not only did you release the DNA, you released lots of proteins in the cell too. Some of these proteins are attached to the DNA. Pineapple juice contains an enzyme which will break up those proteins and make the DNA unravel, making it easier to see. 
7. Slowly pour rubbing alcohol into your cup until it forms a layer equal in volume to your banana soup mixture. The alcohol layer should sit on top of the soup mixture. Swirl mixture.We use rubbing alcohol because it separates the DNA from the rest of the proteins and grease that are in the banana cells. DNA likes to be in alcohol, which is less dense than water—which is what grease and proteins prefer.


8. You should see some whitish stringy stuff at the bottom of your alcohol layer. You can use a wooden stick like a toothpick to ‘spool’ this out of the mixture. Congratulations, you’ve extracted DNA!