The antiparallel arrangement of the two DNA strands gives the molecule two important properties:
Complementary Base Pairing: The antiparallel arrangement of the two DNA strands allows for complementary base pairing between the nitrogenous bases (adenine, thymine, cytosine, and guanine) of the two strands. Specifically, adenine on one strand pairs with thymine on the other strand, and cytosine on one strand pairs with guanine on the other strand. This base pairing is essential for DNA replication and the maintenance of genetic information.
Stability: The antiparallel arrangement of the two DNA strands also gives the molecule stability. The sugar-phosphate backbones of the two strands run in opposite directions, with one strand running in the 5' to 3' direction and the other strand running in the 3' to 5' direction. This allows the hydrogen bonds between the base pairs to be held in a stable configuration, as they are oriented towards each other in a predictable way. Additionally, the stacking interactions between the nitrogenous bases of each strand further contribute to the stability of the DNA molecule.
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