Get Your Hands on DNA

Get Your Hands on DNA

You can become a scientist studying biotechnology by using fruits and vegetables and equipment from your kitchen. By doing this experiment, you will have the opportunity to actually see DNA, the basic building block of life. The first step for many laboratory procedures in biotechnology is to extract, or remove, the DNA from a cell so that it can be studied. In order to work with DNA, the scientist must be able to gently separate DNA from the other unwanted substances of the cell. Amazingly, DNA in the cell of plants, animals, humans, and other living organisms all looks the same. This unique quality of DNA allows us to select and use genes between organisms.

Science Process Skills

Observing

Comparing

Organizing

Relating

Materials (per group)

Kiwi OR tomato OR onion

Shampoo or dish detergent

Salt

Distilled water

Ice

Rubbing alcohol

Two 4-cup measuring cups

One 1-cup measuring cup

Measuring spoons

Knife

Candy thermometer

Large slotted mixing spoon

Strainer

Coffee filter

Large mixing bowl

3-quart saucepan

Stove or hot plate

Small clear container or test tube

Doing the Activity

Fill the 3-quart saucepan half full of water and place it on the stove. Heat the water to 55-60 degrees C.

Fill the large mixing bowl half full of ice.

Using the 1-cup measuring cup, prepare a solution of one tablespoon of shampoo/detergent and Ľ teaspoon of salt. Add distilled water to the measuring cup to make a total volume of 100 ml (1/2 cup or 4 oz.)

Stir slowly to prevent soap from foaming while the salt dissolves.

Chop the fruit or vegetable with a knife. Do not chop too finely. Put the slices in a 4-cup measuring cup.

Cover the fruit or vegetable with the 100 ml solution you made in step 3. The soap/shampoo causes the cell membrane, or outer covering of the cell, to break down. The salt helps the DNA strands come closer together and combine so they are visible.

Place the 4-cup measuring cup with the fruit/vegetable and solution mix down into the hot water for 10-12 minutes. DO NOT pour the solution into the water-place the entire measuring cup with the solution inside into the water. During this time, use the back of the large mixing spoon to slowly press the vegetable/fruit pieces against the sides of the measuring cup. Do this slowly to avoid creating soap suds. The heat treatment helps keep the DNA in large enough fragments so they can be taken out of the cell.

Place the 4-cup measuring cup with the solution in the bowl of ice for 5 minutes. DO NOT pour the solution onto the ice--place the entire measuring cup with the solution down into the water. During this time, continue to press the mixture against the sides of the measuring cup with the back of the spoon. This step slows the breakdown of the DNA.

Position a coffee filter in the strainer and hold it above the second 4-cup measuring cup. Pour the solution slowly into the filter.

Pour a layer of COLD alcohol into a small clear container. Fill the container about 1/3 full. For best results, the alcohol should be as cold as possible.

Add the filtered solution from step 9 on top of the alcohol. Fill the container about 1/3 full. DNA is not soluble in alcohol. When alcohol and the solution mix, it causes the DNA to go into the alcohol layer and everything else to stay in the solution.

Let the container sit for 5-10 minutes. You will begin to see results, as a white, wispy-looking materials becomes visible in the alcohol layer, and it slowly combines to produce white strands made up of several hundred individual strands of DNA.

Reflecting

What does it mean to extract?

Why would we want to extract DNA from fruits and/or vegetables?

Why is it important to breakdown the cell walls and membranes?

Can you list the properties of DNA that were mentioned during this experiment?

Applying

If you were to perform a DNA extraction procedure on bacteria or animal tissue, would you expect a visible different in the results? Why or why not? Try the experiment again. This time use a different fruit or vegetable.
Find out more about genetic and biotechnology careers by visiting:
www.myriad.com/careers.html

What's Happening

DNA is the material in your cells that tell your body how it should operate and look. DNA is found in the cells of nearly every living thing. In humans it is an extremely long molecule. If we stretched out all the DNA in one of your cells, it would be about six feet long. DNA contains the instructions for building proteins. Proteins are the chemical building blocks of living materials. DNA makes proteins, proteins build cells, and cells make up people.

More Challenges

Do the scenario "March of the Mutants" from SimLife.
To find out more about DNA and humans visit: To Know Ourselves: The U.S. Department of Energy & Human Genome Project at: www.lbl.gov/Publications/TKO
Find out more about the basics of biotechnology visit: www.biotech.iastate.edu/biotech_info_series/bio1.html

Activity Source

Iowa State University Extension. Biotechnology School Enrichment Grades 5-6, October 1997. Publication Order # 4H-955C. www.extension.iastate.edu/Pages/pubs

IOWA STATE UNIVERSITY
University Extension

Site contact
E-SET ISU Extension Extension Sites Search
Contact information: Sarah McArdell mcard002@umn.edu
Updated: January, 2000

NNST CYFERNet

	Get Your Hands on DNA
	You can become a scientist studying biotechnology by using fruits and vegetables and equipment from your kitchen. By doing this experiment, you will have the opportunity to actually see DNA, the basic building block of life. The first step for many laboratory procedures in biotechnology is to extract, or remove, the DNA from a cell so that it can be studied. In order to work with DNA, the scientist must be able to gently separate DNA from the other unwanted substances of the cell. Amazingly, DNA in the cell of plants, animals, humans, and other living organisms all looks the same. This unique quality of DNA allows us to select and use genes between organisms.
	Science Process Skills Observing Comparing Organizing Relating
	Materials (per group) Kiwi OR tomato OR onion Shampoo or dish detergent Salt Distilled water Ice Rubbing alcohol Two 4-cup measuring cups One 1-cup measuring cup Measuring spoons Knife Candy thermometer Large slotted mixing spoon Strainer Coffee filter Large mixing bowl 3-quart saucepan Stove or hot plate Small clear container or test tube
	Doing the Activity Fill the 3-quart saucepan half full of water and place it on the stove. Heat the water to 55-60 degrees C. Fill the large mixing bowl half full of ice. Using the 1-cup measuring cup, prepare a solution of one tablespoon of shampoo/detergent and Ľ teaspoon of salt. Add distilled water to the measuring cup to make a total volume of 100 ml (1/2 cup or 4 oz.) Stir slowly to prevent soap from foaming while the salt dissolves. Chop the fruit or vegetable with a knife. Do not chop too finely. Put the slices in a 4-cup measuring cup. Cover the fruit or vegetable with the 100 ml solution you made in step 3. The soap/shampoo causes the cell membrane, or outer covering of the cell, to break down. The salt helps the DNA strands come closer together and combine so they are visible. Place the 4-cup measuring cup with the fruit/vegetable and solution mix down into the hot water for 10-12 minutes. DO NOT pour the solution into the water-place the entire measuring cup with the solution inside into the water. During this time, use the back of the large mixing spoon to slowly press the vegetable/fruit pieces against the sides of the measuring cup. Do this slowly to avoid creating soap suds. The heat treatment helps keep the DNA in large enough fragments so they can be taken out of the cell. Place the 4-cup measuring cup with the solution in the bowl of ice for 5 minutes. DO NOT pour the solution onto the ice--place the entire measuring cup with the solution down into the water. During this time, continue to press the mixture against the sides of the measuring cup with the back of the spoon. This step slows the breakdown of the DNA. Position a coffee filter in the strainer and hold it above the second 4-cup measuring cup. Pour the solution slowly into the filter. Pour a layer of COLD alcohol into a small clear container. Fill the container about 1/3 full. For best results, the alcohol should be as cold as possible. Add the filtered solution from step 9 on top of the alcohol. Fill the container about 1/3 full. DNA is not soluble in alcohol. When alcohol and the solution mix, it causes the DNA to go into the alcohol layer and everything else to stay in the solution. Let the container sit for 5-10 minutes. You will begin to see results, as a white, wispy-looking materials becomes visible in the alcohol layer, and it slowly combines to produce white strands made up of several hundred individual strands of DNA.
	Reflecting What does it mean to extract? Why would we want to extract DNA from fruits and/or vegetables? Why is it important to breakdown the cell walls and membranes? Can you list the properties of DNA that were mentioned during this experiment?
	Applying If you were to perform a DNA extraction procedure on bacteria or animal tissue, would you expect a visible different in the results? Why or why not? Try the experiment again. This time use a different fruit or vegetable. Find out more about genetic and biotechnology careers by visiting: www.myriad.com/careers.html
	What's Happening DNA is the material in your cells that tell your body how it should operate and look. DNA is found in the cells of nearly every living thing. In humans it is an extremely long molecule. If we stretched out all the DNA in one of your cells, it would be about six feet long. DNA contains the instructions for building proteins. Proteins are the chemical building blocks of living materials. DNA makes proteins, proteins build cells, and cells make up people.
	More Challenges Do the scenario "March of the Mutants" from SimLife. To find out more about DNA and humans visit: To Know Ourselves: The U.S. Department of Energy & Human Genome Project at: www.lbl.gov/Publications/TKO Find out more about the basics of biotechnology visit: www.biotech.iastate.edu/biotech_info_series/bio1.html
	Activity Source Iowa State University Extension. Biotechnology School Enrichment Grades 5-6, October 1997. Publication Order # 4H-955C. www.extension.iastate.edu/Pages/pubs