DNA Structure

This sticking allowed two strands of nucleic acid to stick together to form a ladder-like structure, a double-stranded deoxyribonucleic acid.

A double-stranded nucleic acid showing two backbones joined by paired bases

In the diagram we show the two backbones as ball and stick molecules and the paired bases as solid shells. The backbones are coiled around the outside in a double-helix.

Deoxyribonucleic acid is normally called DNA. The "deoxyribo" part of its name refers to the type of sugar which this nucleic acid contains: ribose which has lost one oxygen atom.

The sticking together of bases is very important in life. To understand why, first we will simplify the diagram of double-stranded nucleic acid.

Diagrammatic representation of a double-stranded nucleic acid

We show a double-stranded nucleic acid as if it were straight, not coiled into a helix. We also simplify the four different types of bases and indicate how they stick together.