Final answer:
The genetic code is the sequence of nitrogenous bases A, C, G, and T (or U in RNA) in a polynucleotide chain, which form the DNA or RNA structure. DNA consists of two strands forming a double helix, with base pairing according to Chargaff's rule, aiding in determining the molecular composition of each strand.
Step-by-step explanation:
The genetic code is defined as the sequence of nitrogenous bases in a polynucleotide chain of DNA or RNA which consists of adenine (A), cytosine (C), guanine (G), and thymine (T), or uracil (U) in RNA. DNA is composed of two long chains of nucleotides which form a double helix.
The nitrogenous bases on one strand pair with those on the opposite strand: A with T and C with G, held together by hydrogen bonds. In this DNA section with 20 base pairs, if we know the sequence of one strand, we can deduce the other thanks to the base pairing rules. With Chargaff's rule, stating that A pairs with T and G pairs with C, the molecular composition of each strand can be determined by the number of these bases. Each nucleotide consists of a sugar molecule, a phosphate group, and one of these four bases, which are linked together by phosphodiester bonds.