What is the structural arrangement of DNA?

The structural arrangement of DNA is best described as a double helix composed of two antiparallel strands of nucleotides. This double helix structure was famously elucidated by Watson and Crick in 1953. Each strand of DNA consists of a backbone made of sugar and phosphate groups, with nitrogenous bases attached to the sugar molecules. The two strands are held together by hydrogen bonds between complementary bases: adenine pairs with thymine, and cytosine pairs with guanine.

The term "antiparallel" refers to the orientation of the two strands in the helix, which run in opposite directions. One strand runs in a 5' to 3' direction, while the other runs in a 3' to 5' direction. This orientation is crucial for processes such as DNA replication and transcription, as it influences the way enzymes interact with the DNA strands.

This double helix structure provides stability and protection for the genetic information encoded in the sequences of bases, allowing it to be replicated accurately during cell division and expressed as proteins. The complexity and efficiency of this structural arrangement are fundamental to the functioning of living organisms.