Acommon dna structural feature involved in gene regulatory systems is
a. supercoiling of dna.
b. looping of the dna.
c. unwinding of the double helix.
d. coiling into z-dna.
e. double-strand breakage of dna

good luck

explanation:

i still can't find this

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.