DNA Extraction from Strawberries

Lab Safety and Tips

• Wear Goggles• Important to have

clean glassware.• Follow directions

CAREFULLY or you will not get good results.

I DNA

• Single molecules of DNA are long and stringy. Each cell of your body contains six feet of DNA, but it's only one-millionth of an inch wide.

Chromosomes

• Strands of DNA molecules coated with protein

Start with a Strawberry

• Easy to pulverize• Already has

enzymes• Large genome

(lots of chromosomes)

Add Detergent

• Detergent/shampoo captures protein and releases DNA

Mashing Strawberries in a thick Ziploc bag

Careful!!

You don’t want Bubbles!DNA clings to the bubbles. 

Salt

• The salt in the extraction buffer keeps the DNA molecules together and separates them from the protein.

Filtering the mixture will remove cell debris and organelles.

95% Cold Alcohol

• Alcohol separates the DNA from the other components of the cell

Note: slowly pouring down the side of the test tube

Good Tip

• Be careful to pour down the side of the container to form a layer on top instead of mixing the two layers.

ETHANOL MUST BE COLD!

• The DNA will rise into the alcohol layer and can be ‘spooled’ onto the wooden stick be carefully swirling the stick at the interface of the two layers.

DNA will look like snot

• White• Stringy• You are viewing • the DNA and protein

When DNA extractions are performed, you can expect three

basic results.

• No DNA • DNA appears fluffy which means

it has sheared in the extraction process

• DNA appears as thin threads.

Does you DNA look like this?

If not…Possible Errors

• Impurities could have easily been introduced during any step, which may have altered the outcome.

• Disturbing the solution as the DNA precipitated could cause poor results (probably due to the strands of DNA breaking up).

• Not allowing enough time for each step.