Researchers believe they have found a second code in
DNA in addition to the genetic code.
Loren Williams/Chemistry and Biochemistry, Georgia
Institute of Technology
In a living cell, the DNA double helix wraps around a
nucleosome, above center, and binds to some of its
proteins, known as histones.
The genetic code specifies all the proteins that a
cell makes. The second code, superimposed on the
first, sets the placement of the nucleosomes,
miniature protein spools around which the DNA is
looped. The spools both protect and control access to
the DNA itself.
The discovery, if confirmed, could open new insights
into the higher order control of the genes, like the
critical but still mysterious process by which each
type of human cell is allowed to activate the genes it
needs but cannot access the genes used by other types