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: look at lab background Easy to pulverize- Why? Already has enzymes-Which ones? Large genome (lots of chromosomes)- what is octoploid?

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 –you messed up! DNA appears fluffy – you sheared in the extraction process DNA appears as thin threads. (You Rock!)

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.

You can stain the chromosomes A. make a wet mount of a thin smear of the chromosomes

B. Place one drop of Methylene Blue stain on one edge of the coverslip, and the flat edge of a piece of paper towel on the other edge of the coverslip. The paper towel will draw the water out from under the coverslip, and the cohesion of the water

Protect Your Scope! Be sure to wipe off the excess stain with a paper towel, so you don’t end up staining the objective lenses. CAUTION: Methylene Blue will stain your skin and clothes. Goggles and Aprons are required !