MedzBabba
Great app
Not really !!
Anyway, for those who has no knowledge about DNA, it would worth the try.
DNA Model
okayyy
Nice job
Response from developer
Glad you found it useful! The distinctions you wish to be made are actually already there. Sticks representing double and triple H bonds differ in cross-section, and color is used to distinguish the 3' and 5' ends. This is spelled out in the Useful Stuff popover and illustrated in the Key popover, both available within the app.

