Download DNA Extraction from Strawberries

DNA Extraction Lab
Introduction:
DNA is used by all living (and some non-living) organisms to transfer genetic information from one generation to the
next. The sequence of bases in a strand of DNA contains the information needed for cells to build every protein they
will use. There are 46 chromosomes (strands of DNA) in almost every cell in the human body. These strands form
23 pairs. Many strawberries contain 7 pairs of chromosomes. All the chromosomes in an organism is called the
genome.
Purpose:
The purpose of this lab is to extract DNA from strawberry cells.
Materials:
soap solution
test tubes
glass stirring rod
coffee filter
Procedure:
95% ethanol
strawberries
Ziploc bag
plastic cup
Isolation of DNA from Strawberry Cells
1. Put three strawberries in the Ziploc bag and squish with your hands for 2 minutes.
2. Add 10 mL of the soap / salt solution to the bag, and then smash the strawberry around for one minute or
more until no big chunky parts remain. Then wait 3 minutes.
3. Pour the strawberry mush into a coffee filter that is placed over the top of the plastic cup. Allow the fluid to
collect in the cup. You may have to gentle squeeze the coffee filter to get the juice out into the cup. Be
careful not to tear the filter!!!!!
4. Pour the juice from the cup into a test tube. You only need to fill the test tube about ¼ of the way full.
5. Measure 5mL of 95% ethanol solution. Very, very, very SLOWLY, pour the ethanol down the side of the test
tube. The ethanol should form a distinct layer on top of the juice.
6. Insert a glass rod gently into the ethanol layer only. Gently twist the rod to try and catch some of the white
precipitate (DNA) on the end of it. Do not stir. Sometimes, the DNA may float to the top of the liquid.
7. Clean Up! Throw away filter and Ziploc bag into the garbage can. Rinse the test tubes and cups with water
and return them upside down to the racks so they can dry. Clean and dry all other materials. Wipe down the
lab bench and wash your hands.
Name:_________________________________________Period:____________Date:_______________
Questions – Answer using complete sentences on the back of this sheet of paper or on a separate
sheet. DO NOT answer the question underneath each question! You will lose points!
1. Where is the DNA located in a plant cell? What 3 parts of the plant cell do we need to get through
in order to obtain the DNA?
1
3
2
2. Why did you squish the strawberries in step 1? What part of the cell were you trying to break
down? Hint: You would not have to squish animal cells.
3. The soap solution breaks down the cell and nuclear membranes. How does soap help to break
these down? Hint: You use soap to wash your dishes because it breaks down grease.
4.
If we were to extract DNA from your cheek cells it would look exactly the same as the strawberry
DNA? Do strawberries and humans have the same DNA? If not, what could be different?
5. Why did some groups get more DNA than other groups? Give at least 1 GOOD reason. You can
list several to ensure you get this correct.
Name:_________________________________________Period:____________Date:_______________
Questions – Answer using complete sentences on the back of this sheet of paper or on a separate
sheet. DO NOT answer the question underneath each question! You will lose points!
1. Where is the DNA located in a plant cell? What 3 parts of the plant cell do we need to get through
in order to obtain the DNA?
1
3
2
2. Why did you squish the strawberries in step 1? What part of the cell were you trying to break
down? Hint: You would not have to squish animal cells.
3. The soap solution breaks down the cell and nuclear membranes. How does soap help to break
these down? Hint: You use soap to wash your dishes because it breaks down grease.
4.
If we were to extract DNA from your cheek cells it would look exactly the same as the strawberry
DNA? Do strawberries and humans have the same DNA? If not, what could be different?
5. Why did some groups get more DNA than other groups? Give at least 1 GOOD reason. You can
list several to ensure you get this correct.