Final answer:
DNA is made up of nucleotides, with Chargaff's rules guiding base pairing, and replication being a semi-conservative process ensuring genetic consistency during cell division.
Step-by-step explanation:
The structure of DNA is fundamental to understanding genetic information and how it is replicated and expressed within cells. DNA is a double helix formed by two long strands that spiral around an imaginary axis. The basic building blocks of DNA are nucleotides, each of which consists of a phosphate group, a sugar molecule (deoxyribose), and a nitrogenous base (adenine, thymine, guanine, or cytosine).
Chargaff's rules are empirical observations about the regularity in the ratios of different bases of DNA, stating that in DNA, the amount of adenine (A) equals the amount of thymine (T), and the amount of guanine (G) equals the amount of cytosine (C). This finding was crucial for the elucidation of the double helix structure of DNA, as it implicated the base-pairing mechanism, with A pairing with T and G pairing with C through hydrogen bonds.
DNA replication is a semi-conservative process that occurs when cells divide, ensuring that each new cell inherits an exact copy of the DNA molecule. The double helix unwinds, and each strand serves as a template for the synthesis of a new complementary strand. Cellular mechanisms such as the unwinding of DNA helix, the synthesis of RNA primers, and the assembly of new DNA strands all contribute to efficient DNA replication.