Index >> Virus Structure and Classification >> Single Stranded DNA (ssDNA)

Single Stranded DNA - ssDNa

It may be linear (e. g. parvoiruses) or circular (e- g. φXI74, fd and M13).

First discovered is φX174 by Sinsheimer and his associates in the late 1950s, it differs from double stranded DNA in the following respects:

(1) Ultra violet absorption of dsDNA remains constant from 0 to 80°C, and then rises rapidly (80°C is the critical melting point). ssDNA shows a steady increase in UV absorption from 20°C to 90°C.

(2) dsDNA is resistant to the action of formaldehyde. In ssDNA the reactive sites are exposed, and, therefore it is not resistant to formaldehyde.