Double-stranded DNA consists of two polynucleotides that are arranged such that the nitrogenous bases within one polynucleotide ... Beyond the ladder-like structure described above, another ...

Scientists still needed to figure out this molecule's structure to be sure ... Erwin Chargaff found that the arrangement of nitrogen bases in DNA varied widely, but the amount of certain bases ...

Laying the Groundwork: Levene Investigates the Structure of DNA Meanwhile ... was in turn composed of just one of four nitrogen-containing bases, a sugar molecule, and a phosphate group.

This discovery, along with the identification of other nitrogenous bases, laid the foundation for our understanding of DNA and RNA structure. Cytosine can be synthesized chemically or isolated from ...

nitrogen, and phosphorus. Combinations of these atoms form the sugar-phosphate backbone of the DNA -- the sides of the ladder, in other words. Other combinations of the atoms form the four bases ...