The National Human Genome Research Institute defines DNA as a , a shape resembling a twisted ladder.
The specific sequence of these four bases (A, T, C, and G) creates a biological alphabet that MedlinePlus Genetics compares to letters in a sentence. What is DNA?: MedlinePlus Genetics The National Human Genome Research Institute defines DNA
These are the basic building blocks, each consisting of a sugar, a phosphate, and one of four nitrogenous bases. each consisting of a sugar
The "rungs" are formed by pairs of bases held together by hydrogen bonds. They follow strict pairing rules: Adenine (A) always pairs with Thymine (T) . Guanine (G) always pairs with Cytosine (C) . The Genetic Code The National Human Genome Research Institute defines DNA
The "sides" of the ladder are made of alternating sugar (deoxyribose) and phosphate groups.