Name:_____________________________
S#__________ Date:__________
Hour:_________
Mission: STRAWBERRY DNA Extraction!
Standards: RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments,
taking measurements, or performing technical tasks. WHST.6-8.1 Write arguments focused on
Claims, Evidence, Reasoning. SCI.MS.HER.1 Describe the relationship between genes, proteins,
chromosomes, genomes, and DNA and explain their role in the process of heredity
*I CAN follow a multistep procedure for an experiment about DNA
*I CAN extract DNA and describe its purpose in a strawberry
*I CAN explain why DNA is found in my food
Background: Have you ever wondered what DNA looks like? Today you are going to break
apart the cell membrane of a strawberry and separate the DNA from the nucleus! Strawberries
are a good source of DNA because they have 8 copies of each of their 7 types of chromosomes.
This large number of chromosomes will filter out of your solution and you will be able to
actually see DNA! The long, thick fibers of DNA store the information for the functioning of life.
DNA is present in every cell of plants and animals.
Importance of DNA Extraction: By extracting or isolating DNA, scientists can learn how DNA
encodes the instructions for all life processes. The human genome project has revealed that there
are about 20,500 genes in Human DNA. DNA extraction is important to the study of heredity
(how traits are passed from generation to generation) and to the treatment of many diseases. It
can help diagnose genetic diseases, solve criminal cases, identify victims of disaster and war, and
establish who someone’s parents are. Scientists can genetically engineer changes in DNA to create
disease-resistant plants and animals. DNA extraction is also necessary in order to sequence the
DNA code (order of base pairs) of different organisms and compare different species.
Pre-lab questions: (discuss and answer w/table partner. Tans will check one copy per table group)
1. What do you think the DNA will look like? Draw or explain below
2. What does DNA stand for?
3. In which organelle is a majority of a cell’s DNA found?
4. How many total chromosomes do Humans have vs. Strawberries? (Think Genome)
5. How many copies of Chromosomes do Humans have per cell vs. Strawberries?
SHOW MRS. TANS pre-lab questions. Must get approval before beginning procedure:
*Pre Lab approval Yes:_________ No:________ Fix Question(s):________
Materials: *heavy duty Ziploc bag *1 strawberry *cheesecloth sheet *beaker *scissors
*10 mL DNA extraction buffer (soapy, salty water)-syringe *rubber band
(*cup of 20 mL isopropyl alcohol, wooden skewer- Mrs. Tans will distribute*)
Procedure: (Take turns reading a step, while your partner performs it. Cross off each step’s
NUMBER as you complete it!)
1) Gather materials for you and your table mate.
2) Place one strawberry in a Ziploc bag.
3) Gently smash/grind up the strawberry using your fist and fingers for 1 minutes. Be careful not
to break the bag!!
4) Add the graduated cylinder (10mL) of extraction buffer (salt and soap solution) to the bag.
5) Kneed/mush the strawberry in the bag again for 1 minute.
6) Assemble your filtration system (Cheese cloth on top of beaker with rubber band)
7) Use scissors to cut a small corner slit on your bag. Carefully pour the strawberry slush through
the open slit, into the filtration system and let it drip directly into your beaker.
8) Throw away plastic bag in trash!
9) Get cup of Ethanol and wooden skewer from Mrs. Tans
10) Slowly pour cold ethanol into the beaker. OBSERVE.
11) Dip the wooden skewer into the beaker where the strawberry extract and ethanol layers
come into contact with each other. Stir around until you find something that sticks to it….Did
you find the DNA??? (Check with Table group if you can’t find any!)
***Clean up Procedures****
1) Show Mrs. Tans your DNA for approval! Mission Accomplished? Yes____ Not yet____
2) Throw away in trash- Cheesecloth, plastic bag, strawberry mush, rubber band, paper cup
Rinse out and place on drying rack- beaker, wooden skewer, and graduated cylinders
Return to original location- scissors
******Wipe down table with Clorox wipe******
3) Discuss and Complete Post Lab questions with table group
Conclusions and Analysis: Answer in complete sentences!
1)
What did the DNA from the strawberry look like? Draw or explain below. How did this
differ from your original idea?
2) Why is it important for scientists to be able to remove DNA from an organism? List two
reasons.
3)
Give 3 examples of traits the DNA in a strawberry could code for. (Hint family survey)
4) Is there DNA in your food? Write a CER below to explain!
Claim:
Evidence:
Reasoning: