Final answer:
James Watson and Francis Crick are credited with discovering the 3D double helix shape of DNA in 1953, using Chargaff's rules and the chemical components of DNA: nucleotides, deoxyribose sugars, and phosphate groups.
Step-by-step explanation:
The 3D shape of DNA was discovered by scientists James Watson and Francis Crick, with pivotal contributions from Rosalind Franklin and Maurice Wilkins. They described the double helix structure in 1953. Based on the chemical components of DNA: nucleotides, deoxyribose sugars, and phosphate groups, these scientists knew that nucleotides, which consist of a sugar (deoxyribose), a phosphate, and a nitrogenous base (adenine, cytosine, guanine, or thymine), made up the DNA structure. Chargaff's rules played a critical role in deducing the double helix by revealing that adenine (A) is equal to thymine (T) and guanine (G) is equal to cytosine (C).
The complementary base pairing and the antiparallel nature of the two strands in the DNA helix were crucial discoveries from Watson and Crick's model. These findings contributed significantly to our understanding of DNA replication and the genetic language encoded within.