the structure of dna consists of two strands coiled around each other to form a

The structure of DNA consists of two strands coiled around each other to form a double helix. These two strands are antiparallel, meaning they run in opposite directions. The strands have a backbone made of alternating sugar (deoxyribose) and phosphate groups, with nitrogenous bases (adenine, thymine, cytosine, and guanine) paired inside like steps of a twisted ladder. Adenine pairs with thymine by two hydrogen bonds, and guanine pairs with cytosine by three hydrogen bonds. The double helix shape allows for stable complementary base pairing and efficient packing of genetic information.