FRUIT LOOPSFRUIT LOOPS

STRAWBERRY DNA STRAWBERRY DNA EXTRACTIONEXTRACTION

Did You Know…Did You Know… There are about 2 meters of DNA in each of your There are about 2 meters of DNA in each of your

cells.cells. If all the DNA in your body was put end to end, it If all the DNA in your body was put end to end, it

would reach to the sun and back over 600 times would reach to the sun and back over 600 times (0.983 289 8912 AU - 1.016 710 3335 AU=> avg: (0.983 289 8912 AU - 1.016 710 3335 AU=> avg: 150M km / 93M miles x 600 = 90B km / 720M 150M km / 93M miles x 600 = 90B km / 720M miles => 45 trillion cells – this is disputed, but miles => 45 trillion cells – this is disputed, but definitely in the 10’s of trillions [10^13].definitely in the 10’s of trillions [10^13].

Human DNA is 98% identical to chimpanzee Human DNA is 98% identical to chimpanzee DNADNA

My DNA is 99% identical to your DNAMy DNA is 99% identical to your DNAInstitute for Stem Cell ResearchInstitute for Stem Cell Research

Why Use A Strawberry???Why Use A Strawberry???

Each strawberry cell has a lot of DNA!Each strawberry cell has a lot of DNA!Domestic (store-bought) strawberry cells are Domestic (store-bought) strawberry cells are

octoploids (8 copies of each chromosome)octoploids (8 copies of each chromosome)7 chromosomes per gamete => 56 7 chromosomes per gamete => 56

chromosomeschromosomesMore or Less variability than diploid?More or Less variability than diploid?

Our cells only have 2 copies of each Our cells only have 2 copies of each chromosome.chromosome.

Lab materials….Lab materials….

Freezer bagsFreezer bags1 strawberry1 strawberryDNA extraction bufferDNA extraction bufferFilter paperFilter paperFunnelFunnel Ice cold 99% isopropyl alcoholIce cold 99% isopropyl alcoholTest tubeTest tubePaper clip (or a similar object)Paper clip (or a similar object)

Why do we crush the strawberries?Why do we crush the strawberries?

To break cell walls.To break cell walls.

How do we make extraction buffer?How do we make extraction buffer?

- Combine 100 mL shampoo (w/o - Combine 100 mL shampoo (w/o conditioner)conditioner)

- 15 g non-iodized kitchen salt15 g non-iodized kitchen salt- Fill with water to 1 LiterFill with water to 1 Liter

THIS WILL MAKE 1 LITER OF THIS WILL MAKE 1 LITER OF EXTRACTION BUFFEREXTRACTION BUFFER

Et voila, c’est ca: Un buffer

Why do we add soap to the Why do we add soap to the extraction buffer?extraction buffer?

To break down/emulsify the lipids that To break down/emulsify the lipids that make up the cell membrane and nuclear make up the cell membrane and nuclear membrane.membrane.

Once we break down the nuclear Once we break down the nuclear membrane, we have access to the DNA.membrane, we have access to the DNA.

What is the purpose of adding salt What is the purpose of adding salt to our extraction buffer?to our extraction buffer?

Salt will disassociate into + and – ions.Salt will disassociate into + and – ions.This will uncoil the negatively charged This will uncoil the negatively charged

DNA molecule.DNA molecule.

Why do we use alcohol during the Why do we use alcohol during the final steps of the lab?final steps of the lab?

Alcohol is a polar substance. Alcohol is a polar substance. DNA is nonpolar, therefore, it is insoluable DNA is nonpolar, therefore, it is insoluable

in alcohol.in alcohol.As a result, the DNA will precipitate As a result, the DNA will precipitate

(separate) forming long rope-like DNA (separate) forming long rope-like DNA molecules in the alcohol.molecules in the alcohol.

PROCEDUREPROCEDURE

Smash fruit in freezer bag.Smash fruit in freezer bag. Add 10 mL of extraction buffer. Continue Add 10 mL of extraction buffer. Continue

mashing.mashing. Filter (with filter paper) smashed fruit into Filter (with filter paper) smashed fruit into

a test tube.a test tube. Add 10 mL of alcohol to test tube.Add 10 mL of alcohol to test tube. DNA will precipitate. Use paper clip to DNA will precipitate. Use paper clip to

“grab” DNA!!!“grab” DNA!!!