DNA Lab

In Biology class, since we were learning about DNA and the molecule itself, our teacher decided that it would be a good idea to do an extraction lab! The lab consists of wheat germ, HOT water, alcohol and  dry powder of laundry detergent. I will explain the steps and then show pictures as I continue to tell you what is happening or what happened.

Steps:

1) We needed 1 gram of wheat germ to add to a 50 mL test tube.

2) We needed to place the wheat germ into the test tube after getting the right amount.

3) Now we needed to collect 20 mL of HOT water and mix constantly for 3 minutes.

           - After mixing the solution for 3 minutes it should start to look like and icky dark yellow color with crushed cheerios.

4) After mixing we needed to add 1 mL or a scant 1/4 teaspoon of dry powder laundry detergent and mix gently every minute for 5 minutes. We had to try and not create and foam.

5) Use an eyedropper,pipette, or a piece of paper bowl to remove any foam from the top of the solution.

6) Tilt the test tube at an angle. SLOWLY pour 14 mL of alcohol down the side so that it forms a layer on top of the water/wheat germ/detergent solution. Do not mix the two layers together. DNA precipitates at the water-alcohol interface ( the boundary between the water and alcohol). Therefore, it is crucial to pour the alcohol very slowly so that is forms a layer on top of the water solution. If the alcohol mixes with the water, it will become too dilute and the DNA will not precipitate.

7) Let the test tube sit for a few minutes. White, stringy, filmy DNA will begin to appear where the water and alcohol meet. You will usually see DNA precipitating from the solution at the water-alcohol interface as soon as you pour in the alcohol. If you let the preparation sit for 15 minutes or so, the DNA will float to the top of the alcohol.

   You can usually get more DNA to precipitate from the solution by using one of the DNA-collecting tools (such as a glass or paper clip hook) to gently lift the water solution up into the alcohol. This allows more DNA to come in contact with the alcohol and precipitate. You may find it helpful to pour the water/ detergent solution into a clean test tube, leaving behind the wheat germ, before adding alcohol.

8) Use a glass or paper clip hook or a wooden stick to collect the DNA.

9) Once finished collecting the DNA clean the test tube and the lab area and put away the materials.

After we finished the lab we needed to answer questions. After I show you the questions I will show you pictures of the lab and I will tell you the step we were at when the results happened.

Questions/ Observations:

1) What does the "wheat germ soup" look like?

        The wheat germ soup looked like ramen noodle soup with bread crumbs.

2) How does its appearance change as you add the detergent and swirl it in?

        The wheat germ soup started to turn a brighter yellow as I was continually stirring it. 

3) What do you think is happening at this step?

        The detergent is having a chemical reaction to the wheat.

4) Describe the appearance of the mixture just after you add the alcohol?

        You can see the two layers of wheat germ soup and alcohol.

5) What do you think is happening at this step?

        The DNA is leaking into the alcohol from the wheat germ.

6) What do you observe at the water-alcohol interface?

        The formation of DNA is starting.

7) What does DNA look like?

        It looks like white sticky strings.

Those were our observations of the lab as we were going through the steps. Once we got to the final step we took pictures.

This is the first picture we took. The dull yellow substance is the wheat germ soup. The clear substance is the alcohol. It is layered over the wheat germ as instructed. Now the white stringy stuff is the DNA. It reminded me of cobwebs or really thin, white string. This was the completed results as are the other two pictures.

In this picture you can see the DNA a little better. Kind of weird looking huh? It could also remind you of mucus. Ewww! 

This is the last picture we took and it shows the DNA much better than the others. Like I said before they still remind me of cobwebs stuck together. I hope you enjoyed learning about our DNA lab and I hope you give it a try yourself.