What is DNA?

It is the very substance our genes are made of.  Usually it is depicted as a rope ladder twisted like a helix.  One can say the molecule is shaped approximately like that.  It is in turn built from four smaller molecules.  They are designated A, C, G and T.  A bounds to T and C to G.  In this way DNA can replicate itself under the right conditions.  DNA has to be split along its length by some other suitable substance added for the purpose.  A, C, G and T have to be available.  Then DNA can replicate itself.

The information in DNA is coded in the order of the four smaller molecules.  Other molecules can be folded around it so it becomes easier or harder to read the information.  This can change how a gene is expressed.  But the gene itself is not changed by any environmental factors at all.  That genes would do so I consider superstition.  DNA changes randomly or does not at all.

The substance of DNA was purified already in 1878.  In contrast it long remained unknown what biological function it filled.  This was not discovered until 1953.  Direct decoding of DNA was developed in 1975 – 77.  Further developments of this technology have made it possible for genetic science to make enormous progress.  I have myself seen such being made from the 90ies and on.

A question asked to the scientists in Fråga Lund once was:

Can one see DNA with one’s unaided eye?

The answer was that one sort of can.  One of the scientists showed a bottle containing water and something making it cloudy.  This was around a hundred million of human kidney cells.  (He said they were cultivated so they did not come from a person.)  Dish soap was poured into the bottle which he shook well.  Then he added propanol and shook it well again.  The result was a white, thready lump held together by DNA.  So no-one should claim to me that DNA can’t be seen.

 

Uploaded on the 29th of June 2025.