This is an experiment that allows you to see what DNA looks like.
The DNA shows up because it is clumped together.
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| Question | Hypothesis | Materials
| Lab Instructions | Procedure | Observations
| Conclusion | Discussion | Possible Errors |
In order to make Genetically Modified Organisms, scientists have to remove DNA from a cell. How is that possible?
Precision equipment will be needed to remove DNA from a cell.
2-5oz. Plastic cups
Plastic spoon for measuring & mixing
1 banana
test tubes
1 tsp. clear liquid soap
food processor
#2 coffee filter paper
2 pinches table salt
distilled water
Rubbing alcohol - 99% Isopropyl
The process of extracting DNA from a cell is the first step for many laboratory procedures in biotechnology. The scientist must be able to separate DNA from the unwanted substances of the cell gently enough so that the DNA does not break up.
In this experiment, a banana is treated with salt, water and soap. The salt allows the DNA strands to come together and precipitate out of the alcohol solution. The soap breaks down the cell membrane by dissolving the fatty molecules and proteins of the cell and disrupting the bonds that hold the cell membrane together. The soap then holds on to these pieces, allowing them to be filtered out of the solution by the coffee filter while leaving the cells' DNA in the liquid that drains through the filter.
1. In the food processor, mix the banana with one cup of water. Blend for 15-20 seconds, until the solution is a smooth mixture.
2. In one of the 5oz. cups, make a solution of 1 tsp. of soap and two pinches of table salt. Add 4 tsps. of water. Dissolve the salt and soap by stirring slowly with the plastic spoon to avoid foaming.
3. To the solution made in step 2, add three heaping teaspoons of the banana mixture from step 1. Mix the solution with the spoon for 5-10 minutes.
4. Place a coffee filter inside the second plastic cup. Fold the coffee filter's edge around the cup so that the filter does not touch the bottom of the cup.
5. Filter the mixture by pouring it into the filter and letting the solution drain for several minutes.
6. Obtain a test tube of alcohol. For best results, the alcohol should be as cold as possible.
7. Pour some of the filtered solution into the test tube.
8. Let the solution sit for 2-3 minutes without disturbing it. It is important not to shake the test tube. You can watch the white DNA precipitate out into the alcohol layer.
DNA is not soluble in alcohol. When alcohol is added to the mixture, the components of the mixture, except for DNA, stay in solution while the DNA precipitates out into the alcohol layer. DNA has the appearance of white, stringy mucus.
9. To the remaining banana mixture in the food processor add another banana and mix thoroughly. Add some ice cram and mix until smooth. Enjoy your banana mild shake while waiting for your results. Caution: Rubbing Alcohol is poisonous so make sure not to get any in your milk shake.
As soon as the banana solution was poured into the alcohol, an object appeared resembling a white ice cube in the middle of the test tube. The banana solution settled in the bottom portion of the test tube. It was pale in colour as the banana liquid we poured in to the test tube. The top portion of the test tube contained the clear alcohol. In the centre of it was the 'ice cube'. After several hours the 'ice cube' floated to the top of the test tube. When we removed it on to a dish we discovered it resembled stringy, white mucus, much like that described in the Procedure document.
The hypothesis was incorrect as precision equipment is not needed. However, in order to place the DNA into another organisms cells some kind of equipment will be necassary.
The DNA material became visible almost immediately when we poured the banana solution into the alcohol. The individual strands of DNA are too small to be see with the naked eye, however, when enough of the strands group together, it is visible. The DNA does seem to be very fragile as it deteriorated quickly.
DNA is such a vital part of every living thing, giving each cell its individual characteristics, yet it is easily extracting from a cell. It would be interesting to watch this experiment unfold in a laboratory with equipment strong enough to watch this procedure and to see the individual strands of DNA and then to look even deeper to see the individual genes.
This seemed like a simple experiment as nothing had to be measured or kept at a certain temperature. Impurities could have easily been introduced during any step, which may have altered the outcome. Disturbing the solution as the DNA precipitated did cause poor result probably due to the strands of DNA breaking up.
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