By C. Claiborne Ray

New York Times News Service

Q: If I had a test tube of pure DNA, what would it look like?

The extraction of DNA from a biological sample is relatively easy, and there are test tubes of DNA in colleges, schools and forensic laboratories around the world. Even kits for schoolroom use are readily available.

DNA is a water-soluble acid, and the usual extraction process results in something that looks to the naked eye like clumps of very thin, limp noodles — or soggy cotton candy — floating in the tube.

In the simplest terms, extracting a plant’s DNA begins with crushing the cells of the sample to release the DNA, found in the nucleus. Add a salt solution into which the DNA is easily dissolved, and then add another substance that dissolves surrounding material like fats and proteins.

Finally, the DNA strands are drawn from the purified solution with alcohol. The clumps are visible in the tube where the water meets the alcohol.

An estimated 6 feet of strands of DNA resides in each cell of the human body — a total of 67 billion miles if all the strands in the human body were unspooled and laid end to end.

— New York Times News Service

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