Open the combination lock using the old combination. Remove the u-bar from the lock body so it's in the Unlock position. Use a screwdriver to open the anti-dust cover on the back of the combination lock. Align the old combination numbers to the guide points.
A base pair (bp) is a unit consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix, and contribute to the folded structure of both DNA and RNA.
The number of base pairs does refer to one in a double helix. If it was single stranded, there would be no base pairs, only bases. The number of base pairs varies between DNA molecules.