This represents a short section of the DNA molecule (17 base pairs).
of the DNA double helix are composed of alternating deoxyribose and phosphate groups.
shows as 5-membered rings - 4 greys [carbon] and 1 oxygen [red], with another projecting carbon connecting to
, which is orange with projecting oxygens [red]. Zoom in
.... on a single deoxyribose
and a phosphate
.... Zoom out
The two strands run in opposite directions ('antiparallel') as shown by the 5' and 3' (numbering of the deoxyribose (carbon) atoms connecting to phosphate - spoken as '5 prime' and '3 prime'), labelled at each end. DNA base sequence is read in the 5' to 3' direction.
Across the middle of the molecule are the bases
, each showing several nitrogen atoms in blue. Guanine
(G) is paired with cytosine
(C), and thymine
(T) with adenine
(A). In each case the bases do not directly contact their partner on the opposite strand, to which they are held by hydrogen bonds. Although the bases have alkaline properties on their own, they are enclosed within the DNA double helix and bonded to one another, as well as to the sugar deoxyribose. However the phosphate groups on the outside of the helices provide H+
ions which make the DNA molecule acidic in nature.
* - default
Hydrogens are not shown in this display, except at 3' ends (white dots), but can be added by clicking
Double bonds (in bases and phosphates) are not shown.