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DNA Extraction from Wheat Germ Lab

March 16, 2011

This lab was very easy and straight forward. But most importantly it might have been the very first lab Autumn and I have managed to do correctly.

To start of the lab we placed one gram of raw wheat germ into a test tube and then added 20 ml of warm tap water. We then stirred the mixture together for quite some time, (about 3-5 minutes) as we did this we observed that the mixture turned a yellowish color. Next we added a few drops of Dawn dish washing detergent to the mixture and stirred the new mixture once every minute for five minutes. (the mixture become slightly bluer) After that step we titled the test tube at a little less than a 40 degree angle and very carefully poured 14 ml of alcohol down its side. As we did this the alcohol formed a separate layer on top of the mixture of soap, water, and wheat germ. Finally we let the test tube sit and rest for around eleven minutes. After the time lapse we returned back to the test tube and observed that DNA had precipitated out of the mixture and into the alcohol. The DNA was white and looked very delicate, but nonetheless we fished out the DNA with a stirring stick and got a better look at it! Once Autumn and I had finished celebrating our excitement in doing our first lab correctly we cleaned up our mess and dumped the mixture down the sink!

Discussion Questions:

1. What does the “wheat germ soup” look like?

– The “wheat germ soup” looks cloudy yellow in color.

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

-As we added the detergent and swirled it, the appearance of the “wheat germ soup” became a blue-green cloudy color.

3. What do you think is happening during this step?

-At this step I think that detergent is destroying the cell membrane of the wheat and allowing for DNA to come out of the cell.

4. Describe the appearance of the mixture just after you add the alcohol.

-Just after we added the alcohol there was two separate layers between the mixture and the alcohol and on top of the alcohol there was a small layer of white stuff.

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

-At this step and then the DNA is rising out of the soup and going into the separate layer of alcohol.

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

-We observed the DNA precipitate out of the mixture and into the alcohol.

7. What does DNA look like?

-The DNA was white, long, skinny, and looked very delicate.

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