DNA Discussion

The scientists James Watson and Francis Crick first characterized DNA structure in 1953.  They elucidated that DNA exists in a helical fashion, held together by the magic tricks of hydrogen bonds, and consisting of four nitrogenous bases adenine, thymine, guanine, and cytosine.  These bases are held together by 3’-5’ phosphodiester bonds.  In eukaryotic cells, each strand of DNA is wrapped around protein structures known as histones.  Typically, there is approximately 146 base pairs wrapped 1.65 turns around each histone structure.  Ratios and sequences of bases remain varied depending on the source of DNA.  The DNA of prokaryotic cells remains much the same, however exists in a circular double helical fashion referred to as a plasmid.