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Name: DNA Lover
Status: Student
Grade:  6-8
Location: CA
Country: United States
Date: January 2006


Question:
Hello, I've found out about extracting DNA is possible, on the internet and I wanted to show it to my teacher. But she didn't believe me and asked me if I can prove it. There are so many sites on how to extract DNA but never has a real proof (only an explanation).

So do I need molecular microscope (?!) or something to really look and see if it is DNA?

If so, do you know where my isolated DNA can be looked at without buying an instrument?



Replies:
Most of the standard DNA extraction procedures where the last step is often twirling the gooey DNA polymer around a stirring stick of some sort and pulling it out of solution have been shown by chemical analysis to be made of DNA by chemical analysis. If you search the internet, you should be able to find multiple reputable sources that use procedures similar to the one I imagine you have found. By the way, scientists seldom "prove" anything. But we do succeed in convincing reasonable people by both inductive and deductive logic...once we have the data. In your case your teacher should be convinced by more than one citation of a reputable source that has published the procedure.

Here is one reputable source...

http://gslc.genetics.utah.edu/units/activities/extraction/

pf


There are many ways to verify your solution contains DNA, but most require sophisticated instruments. Here are a couple of ways you could support the conclusion you have isolated DNA.

This method requires a spectophotometer available in most university research labs. When DNA is heated to 90 deg. C, the UV light absorption of the DNA will increase at a wavelength of 260 nm. This is because the complementary strands of DNA absorb more UV light when they are single-stranded.

If your DNA sample is viscous (syrupy), if you add DNAse to your sample, the the viscosity will decrease. The viscosity can be measure by sucking the DNA up into a 1 mL pipet and measuring the length of time it takes for the DNA to drain from the pipet by gravity. After exposure to DNAse, the smaller DNA molecules will have a lower viscosity and therefore drain from the pipet faster. DNAse can be purchased from Sigma Chemical Co.

Good luck,

Ron Baker, Ph.D.


What do you expect to see when you look under the microscope. If you think you will see a series of A's C's T's and G's you will be disappointed. It will look like a mass of ropey goo. What you will be seeing is a mass of the DNA from millions of cells all tangled together. There is so much DNA you can see it without a microscope.

If you want a reliable easy way to extract DNA, go to the Genetic Science Learning Center website at the University of Utah. (You can google it). They have an easy do it at home recipe.

Maybe you can convince your teacher to do it as a lab in class.

vanhoeck



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