Final answer:
DNA is formed from nucleotides that create a double helix, with antiparallel strands linked by hydrogen bonds between complementary base pairs and a sugar-phosphate backbone. Adenine pairs with thymine, and guanine pairs with cytosine, forming two and three hydrogen bonds respectively. The structure is stabilized by phosphodiester bonds and is vital for genetic information storage and transfer.
Step-by-step explanation:
Structure of DNA
DNA, or deoxyribonucleic acid, is the hereditary material in organisms, and its structure is critical to its function in storing and transferring genetic information. DNA is composed of nucleotides, each consisting of three components: a 5 carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base. These nucleotides are linked together by covalent phosphodiester bonds to form the DNA strands.
The DNA molecule is a double helix, with two strands that run antiparallel to each other. This means one strand runs in a 5' to 3' direction, and the other runs from 3' to 5'. The strands are held together by hydrogen bonds between complementary base pairs: adenine (A) pairs with thymine (T) forming two hydrogen bonds, and guanine (G) pairs with cytosine (C) forming three hydrogen bonds. This base pairing is critical for the replication of DNA and the transmission of genetic material.
The double helical structure of DNA with its base pairs was first proposed by Watson and Crick, building on the discoveries by Chargaff as well as Franklin and Gosling's X-ray crystallography data. The exterior of the DNA double helix is formed by the phosphate-sugar backbones, while the bases are on the inside, mediating the hydrogen bonding that stabilizes the helical structure.