Do the two DNA double helices following DNA replication have the same, or a different, composition?
The two DNA double helices following DNA replication have the same composition. During the process of DNA replication, an enzyme called DNA polymerase synthesizes two new strands of DNA, one for each of the original template strands. This is known as semi-conservative replication, meaning that each new DNA double helix contains one original (parental) strand and one newly synthesized (daughter) strand.
To visualize this process, imagine unzipping the DNA double helix. Each of the separated strands serves as a template for the synthesis of a complementary new strand. The nucleotides (building blocks of DNA) are added to the growing strands according to the base-pairing rules, with adenine (A) pairing with thymine (T) and cytosine (C) pairing with guanine (G).
In other words, if one original DNA strand has the sequence ATCG, the newly synthesized strand will have the complementary sequence TAGC. Similarly, the other original DNA strand will be copied to produce a complementary daughter strand.
Overall, both newly synthesized DNA strands have the same nucleotide composition as their parent strands, resulting in two identical DNA double helices.