What is antiparralell?

Antiparallel refers to two items, such as strands of DNA or two magnetic fields, that run parallel to each other but have opposite directions. In the context of DNA, antiparallel strands run in opposite directions because they are oriented with their 5' and 3' ends in opposite directions. This is important because it allows for complementary base pairing between the nitrogenous bases on the two strands, which plays a critical role in the double helix structure. In the context of magnetic fields, antiparallel fields can neutralize each other's effects, resulting in a cancellation effect.