Biology Question #9401

Liam Christy, a 15 year old from Kamloops asks on April 12, 2017,

I was wondering if it's possible to extract viable DNA amateurely. I want to conduct an experiment involving tardigrades and glowing jellyfish DNA. Is it possible for me to simply extract this DNA so I could expose tardigrades to it and see if they would absorb this DNA and mutate?

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The answer

Caryn Dooner answered on April 13, 2017

Isolating DNA typically consists of three main steps. Once you have the tissue sample (such as a jellyfish or part of a jellyfish depending on how large they are, or in the example I used already a chunk of banana), so first you need lyse the cells in the tissue. The DNA is contained in the cells of the tissue, so you need to "break" them open. Typically this is done using hot water and a detergent, like dish soap. Once you've broken open the cells with heat and detergent, now you have a mixture of water, proteins, cell membranes (along with other bits of the cell), and DNA. You only want the DNA, so the second step involves filtering the DNA. For this you can use a coffee filter. You can take the hot water/banana/detergent mixture and pour it into a coffee filter resting on a cup. This will take a few minutes - you need to wait until all the liquid (and DNA) passes through the filter and ends up in the cup. Now you have DNA in water. But where's the DNA?! You can't see it. So the next step will be to visualize the DNA, which is the third stage. To do this, you will need cold alcohol. Rubbing alcohol is good because it has a very high percentage. It is VERY important that the alcohol is cold. If possible, leave it in the freezer for a couple hours leading up to when you plan to do the experiment. The cold alcohol will cause the DNA to precipitate out of the water, and what you should see form is long white strands. That's the DNA! 

 
So now that I've explained how to isolate DNA in an "amateur" manner, there's a couple things I would like to go over. Visualizing DNA is really cool - it's one of my favorite parts of genetics. But aside from being able to see a strand, what does this experiment (isolating DNA) actually tell you? The cool thing about DNA is that it's like a set of instructions. In order to make sense, you need to read them. Just seeing them and knowing they are there (like in this experiment) doesn't really tell you what the instructions are. So if you took a banana and lets say a strawberry, obviously they have different DNA. But if you did this experiment, you would just get two white strands, which wouldn't really tell you how the DNA is different between a banana and a strawberry. [So even if you could get similar white DNA strands from your jellyfish, you wouldn’t be able to tell which part of the strand are the DNA instructions for the protein that causes the jellyfish to glow.] So that is the first problem: I'm not sure that you can tell from an experiment like this whether the DNA you exposed the tardigrades to would result in a mutation. 
 
The second issue I want to go over is exposing tardigrades to foreign DNA. The first step in this kind of experiment is to lyse the cells, which means to break them open. In order to get DNA into or out of cells, you need to bypass the "shell" of the cell, the cell wall. Just exposing a cell to DNA won't result in the cell taking up the DNA. There is one exception to this, but it is not in tardigrades. You can make bacterial cells take up DNA by altering temperature or exposing them to an electric current, however this principle, as I said, would not work for tardigrades. Unfortunately you would need a way to get the jellyfish DNA into the tardigrade cells, which can be done through a process called "microinjection", but you would need a very sophisticated research lab and special equipment to do it. The process basically involves sticking a very tiny needle into a tardigrade cell and injecting the jellyfish DNA, and you need a hydraulic machine and sterile environment to make sure there is a proper chance of it working.

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