2. What are the three parts of this subunit/monomer?
3. Describe the appearance of the DNA you re">
Subunit or monomer of the DNA structure...

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"1. What is the subunit or monomer of the DNA structure?
2. What are the three parts of this subunit/monomer?
3. Describe the appearance of the DNA you retrieved.
4. What is the role of the blender in this experiment?
5. What is the role of the salt and the shampoo in this lab?
6. Why were coffee filters (or cheesecloth) used within this experiment?
7. Why did you pour the solution with the DNA into the alcohol?
8. Why can't we see the double helix shape of the DNA?
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DNA IN MY FOOD LAB.doc Download Attachment
DNA IN MY FOOD???
The Making of a Smoothie
Prepared by the Office of Biotechnology, Iowa State
University and then adapted by Mosley
In this protocol students will extract DNA from bananas
that have been blended with water. A portion of the
banana mixture is then treated with shampoo and salt
mixed for 5-10 minutes, and then strained through a
coffee filter. The filtrate is added to cold alcohol and the
DNA from the banana solution precipitates (becomes
visible).
Materials
2- 5 oz plastic cups
blender
plastic spoon for measuring and mixing
#2 cone coffee filter
20 ml of distilled water
clear-colored shampoo, such as Suave Daily
Clarifying Shampoo
3- bananas
table salt, either iodized or non-iodized
1- plastic transfer pipette or medicine dropper
1- sealed test tube containing 95% ethanol (grain
alcohol) or 91% isopropyl (rubbing) alcohol
1- container with ice for cold alcohol tubes
laboratory instructions
Lab Instructions
Extract the DNA
DNA is present in the cells of all living organisms. This
procedure uses household equipment and store supplies to
extract DNA from banana in sufficient quantity to be seen
and spooled.
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 denature (break up.)
You will prepare a solution of banana treated with salt
distilled water, and shampoo (detergent). The salt allows
the DNA to precipitate out of a cold alcohol solution. The
detergent breaks down the cell membrane by dissolving
the lipids (fatty molecules) and proteins of the cell and
disrupting the bonds that hold the cell membrane together.
The detergent then forms complexes with these lipids and
proteins, allowing them to be filtered out of solution by
the coffee filter while leaving the cells' DNA in the
filtrate.
Procedure
1. In a blender, mix a ratio of one banana per one cup
(250ml) of distilled water. Blend for 15-20 seconds
until the solution is a mixture. (Your teacher is
doing this step for you)
2. In one of the 5 oz cups, make a solution consisting of
1 teaspoon of shampoo and two pinches of table salt.
Add 20 ml (4 teaspoons) of distilled water or until the
cup is 1/3 full. Dissolve the salt and shampoo by
stirring slowly with the plastic spoon to avoid
foaming.
3. To the solution you 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.
The salt enables the DNA strands to precipitate.)
4. While one member of your group mixes the banana
solution, another member will place a #2 cone coffee
filter inside the second 5 oz 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 until
there is approximately 5 ml (covers the bottom of the
cup) of filtrate to test.
6. Obtain a test tube of cold alcohol.
7. Fill the plastic pipette with banana solution and add it
to the alcohol.
(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.)
8. Let the solution sit for 2 to 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. When good results are
obtained, there will be enough DNA to spool on to a
glass rod. Or by using a pasteur pipette that has been
heated at the tip to form a hook, you can retrieve
some of the DNA.
Conclusion Questions
1. What is the subunit or monomer of the DNA
structure?
2. What are the three parts of this subunit/monomer?
3. Describe the appearance of the DNA you retrieved.
4. What is the role of the blender in this experiment?
5. What is the role of the salt and the shampoo in this
lab?
6. Why were coffee filters (or cheesecloth) used
within this experiment?
7. Why did you pour the solution with the DNA into
the alcohol?
8. Why can't we see the double helix shape of the
DNA?"

 

Solution ID:350799 | This paper was updated on 26-Nov-2015

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