What bases that interacts for base pairing and know the functional groups that become acceptors and donors in hydrogen pairing.

So the bases form complementary base pair with each other ,the very obvious question is how do they get the role of acceptor and donor to have correct base pairing,

This is as such the A-T and G-C pairs maximize the number of hydrogen bonds across the shared helical axis. A's hydrogen donors can pair up with T's hydrogen bond acceptors, and G's hydrogen bond acceptors can pair up with C's hydrogen bond donors. A-T and G-C are called complementary base pairs

ADAM =A:T

AADH = G:C

HDAA= C:G

MADA =T:A

A=H-bond Acceptor
D=H bond Donor
M=Methyl group
H=non polar hydrogen

So when ever we have such arrangement we can easily tell whether the base can act as an acceptor or a donor