antiparallèle

Antiparallèle describes the arrangement of two or more elements along a common axis but oriented in opposite directions. The concept contrasts with parallel alignment, where components point in the same direction.

In biology, antiparallel is most famously applied to DNA. The two polynucleotide chains run in opposite directions within the double helix: one strand is oriented 5' to 3' while the other is 3' to 5'. This antiparallel arrangement is fundamental to DNA replication, transcription, and the overall structural stability of the molecule.

In physics and materials science, antiparallel can describe magnetic moments that align in opposite directions. In antiferromagnets, adjacent spins oppose each other, resulting in a small or vanishing net magnetization under certain conditions. Antiparallel alignment can also influence exchange interactions and magnetic properties at the atomic level.

In electronics, antiparallel typically refers to two diodes connected in parallel but facing in opposite directions. This configuration allows current to flow in both directions, enabling bidirectional clamping, protection against voltage spikes, and certain forms of AC rectification.

The term is used more broadly to denote any scenario where paired elements are oriented along the same axis but in opposite directions. Understanding antiparallel arrangements helps explain phenomena in molecular biology, magnetism, and electronic circuit design.