What is the stucture of DNA?

DNA is a double helix structure composed of two long strands of nucleotides. Each nucleotide is made up of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or thymine). The nucleotides are linked by covalent bonds between the sugar and phosphate groups, forming a sugar-phosphate backbone. The nitrogenous bases form hydrogen bonds between complementary bases on the opposite strand, holding the two strands together.