Biology - HOT Science Lab

Student
DNA Extraction Lab
NGSSS:
SC.912.L.16.3 Describe the basic process of DNA replication and how it relates to the
transmission and conservation of the genetic information. (AA)
Background Information:
DNA is too small to see under a regular microscope, so how can it be studied DNA is a large
molecule found in all living things; therefore it is possible to extract it from cells or tissues. All we
need to do is disrupt the cell‘s plasma membrane and nuclear envelope, make the DNA clump
together and - voila! - DNA extraction is possible. DNA extractions from onion, bananas, liver, or
wheat germ are commonly used in laboratory investigations.
Plants used in agriculture and horticulture are often artificially selected for their large flowers and
fruits. Strawberries are no exception; wild strawberries are not as large as the ones you get in
the grocery store. Strawberries are octoploid, meaning that they have eight copies of each type
of chromosome. With eight sets of chromosomes, they have plenty of DNA for classroom
extraction.
Problem Statement: Do you think you have ever eaten DNA
Safety:
Handle breakable materials with care. Do not touch broken glassware.
If you are allergic to certain plants, tell your teacher before doing activity in which plants
are involved. Wash your hands when you are finished with the activity.
Flammable materials may be present. Make sure no flames, sparks, or exposed heat
sources are present.
Vocabulary: extraction, buffer, octaploid, chromosome, artificial selection
Materials (per group):
Ziploc baggies
Small (10 mL) graduated cylinders
Beakers or cups for straining
Cheesecloth
Test tubes and containers or racks to
hold them
Wood splints or disposable
inoculation loops
Strawberries
Extraction solution (10% shampoo
and a dash of salt)
Ice cold ethanol (70% pharmacy
ethanol will work)
Procedures:
1. Smash several strawberries in a Ziploc baggie for 1 minute.
2. Add 10 mL extraction solution.
3. Smash solution/berry mix for an additional 1 minute.
4. Filter through cheesecloth.
5. Pour 2-3 mL of filtrate into a test tube.
6. Layer twice this volume (4-6 mL) with ice cold ethanol.
7. Stir gently with inoculation loop and spool DNA as it clumps at the EtOH (ethanol)/filtrate
interface.
Biology HSL Page 201
Curriculum and Instruction