trial&error vs knowledge

In gammaRetrovirus signal there is a little 6-base loop on the left that I was only able to
configure correctly by making it r-r-r/g-r-g… I arrived at this by trial and error. (Nothing else seemed to work). Is there some biology principal at work here that can be applied
for future puzzles?

Hi stansch -

please check out the strategy guide written by players. They explain well how loops and stacks form and why