Final answer:
DNA's structure is a double helix with strands comprising nucleotides, connected by complementary base pairing where adenine pairs with thymine and cytosine pairs with guanine, with antiparallel orientation.
Step-by-step explanation:
Watson and Crick proposed that DNA is made up of two strands that are twisted around each other to form a right-handed helix. Base pairing takes place between a purine and pyrimidine, so that A pairs with T and G pairs with C. Adenine and thymine are complementary base pairs, and cytosine and guanine are also complementary base pairs. The base pairs are stabilized by hydrogen bonds; adenine and thymine form two hydrogen bonds and cytosine and guanine form three hydrogen bonds. The two strands are anti-parallel in nature, and the sugar and phosphate of the nucleotides form the backbone of the structure, whereas the nitrogenous bases are stacked inside, like the rungs of a ladder.
The structure of DNA is that of a double helix, which consists of two strands of nucleotides that twist around each other. Each nucleotide is composed of a 5 carbon sugar, a phosphate group, and a nitrogenous base. The strands are connected through complementary base pairing, where adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). These bases form hydrogen bonds, with A and T forming two hydrogen bonds, and C and G forming three, which helps to stabilize the double helix structure. Furthermore, the two DNA strands run in antiparallel directions, meaning one strand runs from the 5' to the 3' end while the other runs from the 3' to the 5' end.