How to get DNA from common food items

A routine procedure to collect DNA for subsequent molecular or forensic analysis.

DNA is extracted from human cells for a variety of reasons. With a pure sample of DNA you can test a newborn for a genetic disease, analyze forensic evidence, or study a gene involved in cancer.

1. Break the cells open to expose DNA2. Remove membrane lipids by adding

detergent3. Precipitate DNA with an alcohol — usually

ethanol or isopropanol. Since DNA is insoluble in these alcohols, it will aggregate together, giving a pellet upon centrifugation. This step also removes alcohol-soluble salt.

University of Utah◦ Genetic Science Learning Center:

http://learn.genetics.utah.edu/content/labs/extraction/

Strawberries Bananas Green Peas Wheat Germ

½ cup of DNA (peas, strawberries, bananas)

Large pinch of table salt (less than 1/8 teaspoon)

Twice as much coldwater as DNA source(about 1 cup)

Blend on high for15 seconds

Some protocols require heating at a low (50’C) temperature to ensure that all of the cell wall material is broken down.

Filter or strain out the extra material and the “naturant” solution containing DNA can be used for the extraction.

Add about 2 tablespoons of detergent, swirl to mix.

Let the mixture sit for 5-10 minutes.

Blending separated the cells, but each cell is surrounded by a sack (the cell membrane). DNA is found inside a second sack (the nucleus) within each cell.

To see the DNA, we have to break open these two sacks using detergent.

A cell's membranes have two layers of lipid (fat) molecules with proteins going through them.

When detergent comes close to the cell, it captures the lipids and proteins.

Pour the mixture into test tubes or other small glass containers, each about 1/3 full.

Add a pinch of enzymes to each test tube and stir gently.

Be careful! If you stir too hard, you'll break up the DNA, making it harder to see.

Enzymes are proteins that help chemical reactions happen more quickly. Without enzymes, our bodies would grind to a halt.

In this experiment, the enzyme we use comes from meat tenderizer and cuts proteins just like a pair of scissors.

You can also use fresh pineapple juice or contact lens cleaning solution as an enzyme.

The DNA in the nucleus of the cell is molded, folded, and protected by proteins. The meat tenderizer cuts the proteins away from the DNA.

Tilt your test tube and slowly pour rubbing alcohol) into the tube

Pour it down the side so that it forms a layer on top of the fruit mixture.

Pour until you have about the same amount of alcohol in the tube as fruit mixture.

DNA will rise into the alcohol layer from the fruit layer

Use a wooden stick draw DNA into the alcohol

Alcohol is less dense than water, so it floats on top.

Since two separate layers are formed, all of the grease and the protein that we broke up in the first two steps and the DNA have to decide which layer to go to.

In this case, the protein and grease parts find the bottom, watery layer the most comfortable place, while the DNA prefers the top, alcohol layer.

DNA is a long, stringy molecule that likes to clump together.

Compare it with DNA extracted from other sources.

You may want to save it inside of a vial of alcohol.

The vial containing DNA may be made into a wearable necklace: