In which of the following ways are dna and mrna different? only dna can be read by trna molecules during replication to form copies of the genetic information in the original dna. only dna contains adenine, guanine, and cytosine in a sequence that can be used to make proteins by unzipping and base pairing in the nucleus. only dna has a single stranded structure which can be replicated to form complementary strands. only dna serves as the master copy of an organism's genetic code which must be replicated by unzipping and base pairing before the cell divides.