Avery, MacLeod, and McCarty showed that DNA is required for the transformation of bacteria. Some of the salient features are that the two strands that make up the double helix have complementary base sequences and anti-parallel orientations.

Alternating deoxyribose sugars and phosphates form the backbone of the structure, and the nitrogenous bases are stacked like rungs inside. DNA was first isolated from white blood cells by Friedrich Miescher, who called it nuclein because it was isolated from nuclei.

transformation — process in which external DNA is taken up by a cell. salient features — that the two strands that make up the double helix have complementary base sequences and anti-parallel orientations. nitrogenous bases — stacked like rungs inside. leading strand — strand that is synthesized continuously in the 5'-3' direction, which is synthesized in the direction of the replication fork.