Final answer:
The antiparallel nature of DNA refers to the orientation of the two strands in the double helix, where one strand runs from 5' to 3' and the other strand from 3' to 5', enabling base pairing between adenine-thymine and guanine-cytosine with hydrogen bonds.
Step-by-step explanation:
The antiparallel nature of DNA refers to the opposite orientation of the two strands in the double helix structure. In the DNA molecule, the two strands are twisted around each other with one strand running in a direction from the 5' end to the 3' end, while the complementary strand runs in the opposite direction, from the 3' end to the 5' end. This antiparallel configuration is critical for the complementary base pairing that occurs between adenine (A) and thymine (T), and between guanine (G) and cytosine (C), which is stabilized by the formation of hydrogen bonds.
The phosphate backbone of each DNA strand is situated on the exterior of the molecule, whereas the nitrogenous bases are located inside, pairing with complementary bases across the two strands. This arrangement not only supports the structural integrity of the double helix but is also essential for processes such as DNA replication and transcription.