Do it yourself DNA

[susteacher]

My daughter and I really enjoyed doing this project with the strawberries. She's making it her own, by trying out different fruits. We selected them by researching which foods are octoploids or have multiple copies of genes. Now to my question, the DNA absolutely precipitated and we could see it, but we could not get the DNA to stick to anything outside of the test tube. I could get a picture as it fell off of part of a clothespin (the only wood item we had in the house.) We were using metal skewers, since that was all I could find. As we are redoing it today, she is thinking she used too much salt in her extraction solution yesterday--1 tsp instead of 1/2 tsp. Any chance this could have been the problem? Also, we're trying bananas. The mixture is so think, even after mashing that's it's not coming through the cheesecloth very well. Could we add more water? Could we run it through a blender? What might help?

[cbrambley]

Hey there,

I would suggest to use a thinner wooden object, ideally something like a toothpick or chopstick. Try to gently rotate the toothpick so that the dna spools around it. I'm not really sure if adding too much salt affects this, but it couldn't hurt to play with the proportions a little and see what happens. As for your banana problem, you could either try using more of the extraction liquid, or less banana. Of course make sure you're mashing it up well enough. Oh and also I used to use coffee filters instead of cheesecloth. I'm not sure if that'll help you much, but it's something to try if you have coffee filters on hand.

Hope that helps!

[susteacher]

Thanks for the ideas! We gave up on the different fruits and compared detergents instead. We had another detergent do better detergent wise, but never could get it removed. We took pictures to document instead.

[sjrogers113]

Hello,
My daughter is doing this experiment with strawberries and using different detergents to see which one precipitates more DNA. They are required to use the scientific method. I believe that requires for them to be able to measure the results, and provide it as data so that we can make a graph or chart. We tried to weigh what we were able to get on a skewer, but it is so light that it doesn't register on the scale. Any ideas of how we can record the results of this with data? We would like to do a chart or graph because I think the scientific method requires that, but I'm not sure.
Thank you,
Shelley

[connief]

Hi sjrogers113,

To answer your question, as far as I know, there is no easy way to weigh or quantify the amount of DNA you extracted without more sophisticated lab equipment. Perhaps other experts may have more ideas of how to determine DNA amounts using items that are easily accessible for younger students. The scientific method doesn't necessarily require you to make a measurement. You can just record what you observe. For example, with the detergents you used, were you able to extract DNA from the strawberries? How were these detergents different from each other? Did you use detergents from different brands, or did you just use different concentrations of the same detergent? When you look by eye and estimate, which detergent condition seems to extract the most DNA?

Let us know if you have anymore questions!

Connie

[sjrogers113]

Thanks Connie. I wasn't sure if we had to quantify the results. We have always done charts and graphs in previous years, so hopefully pictures will be sufficient. We used 3 different types of detergents: Joy dish soap , Cascade dishwasher liquid detergent, and All laundry detergent. There was significantly different results with each of them. The Joy pulled the most by far, the All laundry soap was next, but the Cascade dishwasher detergent was almost none and interestingly it turned the strawberry mixture to a purple color while the other two remained red. So it was a very interesting experiment, I just hope she won't lose points for not having charts and graphs. I was thinking maybe if we graded the results ourself by visually giving them a score on a scale of 1 - 5 and graph that. However, I'm not sure that would be very scientific ?
I welcome any additional ideas or input. Thanks!

[connief]

I think giving each a score based on what you observe visually will be great. However, you have to be careful in deciding what is defined as a "1" and what is defined as a "5". You may want to have a negative control where you don't add in any detergent at all and see how that looks like--you can set that as your 0 or 1 (based on what number you define as "nothing extracted") and then perhaps compare the samples you've treated with detergent to that control to see where they lie within the scale.

Let us know if you have more questions!

Connie

[sjrogers113]

Great! I think that is what we will do then. We will add one more extraction sample with no detergent so we can use that as the zero value and then use visual judgments to assign values to the others. Then we will be able to do a graph and chart, which I think would make it a better project and meet the requirements of providing data analysis.
Thank you so much Connie!
Shelley