Trusted local news leader for Prescott area communities since 1882
Tue, March 19

Does anyone know how DNA works?

What is this DNA stuff anyhow?

I frequently read newspaper stories that involve DNA in some way, and it makes me feel very ignorant.

They have been able to identify tiny fragments of bodies at the World Trade Center site using DNA and turn them over to the related families.

Weeks ago news came out about scientists recovering DNA from Neanderthal bones that were more than 30,000 years old.  Scientists are studying this material and comparing it with modern human DNA.

Thomas Jefferson had children by his black slave, Sally Hemmings ‹ suspected, but proven only a few years ago by DNA.

It was heavily involved in the allegation that three members of the Duke University lacrosse team raped a stripper at a private party. No DNA evidence supported the stripper's claim, but the district attorney charged the boys with rape anyhow. Now the D.A. is in trouble for suppressing evidence that the stripper's body and clothes showed plenty of DNA from semen from other men.

Of course, anyone who watches "CSI" knows that investigators use DNA to match suspects with the evidence left at crime scenes ‹ or to disprove a connection.

This week the news is about using DNA to discover the identities of missing people. Scientists can connect tissue from unidentified bodies, dead and buried many years ago with

existing family members.  

Nothing is more certain than DNA, said Sgt. Mary Roberts of the Phoenix police. It's our answer to solving crimes from 30 years ago.

I give credence to these stories because DNA has such worldwide acceptance today. But I simply do not understand it. Do you?

DNA is short for deoxyribonucleic acid, but you can forget that because it means nothing to most of us.  

Every cell of every organism has DNA which controls the function of that particular cell. Some of it comes from male ancestors, some from female, some from both; and this helps scientists do their identifications.

Every molecule of human DNA contains 3.3 billion bits of coding. That's incredible, but apparently true. Segments of the molecule make up the basic units of inheritance that we call genes. One gene may determine eye color, another height. All of the genes collectively provide a blueprint for every organism and determine its anatomy and physiology. (My personal hypothesis is that genes also influence how we think.)

Your DNA and mine are 99.9 percent identical. It's that tiny 0.1 percent remainder that makes us look, think, and act differently. It's also enough to tell whether a suspicious hair came from your head or mine.

We humans share almost 99 percent of our genes with chimpanzees ‹ our closest relatives in the animal world. We also share 90 percent with mice,

60 percent with flies and 40 percent with various plants.  

DNA molecules change with every generation, so it's easy to theorize that life started with an original set of blueprints and gradually evolved.

Most of the DNA seems to serve no purpose ‹ it's what they call "junk DNA" ‹ but surprisingly, it's some of this junk stuff that scientists use for the forensic comparisons which prove whether you're guilty or innocent.

Somehow, with techniques and equipment that I don't understand, "they" can compare your DNA with a specimen's DNA and determine whether that specimen came from you. It's somewhat like matching fingerprints except that they're dealing with billions of bits of information within a single cell.  

If you know how they do this, and can explain it in layman's terms, please give me a call. I'll pass it on to those readers who lust for such knowledge.

Until then, just accept on faith that it works ‹ just as you do for microwave ovens, atomic bombs and Google.


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