Final answer:
Significant discoveries in the 1900s established DNA as the molecule responsible for inheritance, with its double helix structure, base pairing rules, and the identification of enzymes for DNA manipulation.
Step-by-step explanation:
Discovery and Understanding of DNA:
In the 1900s, pivotal discoveries transformed our understanding of genetics and inheritance. It was found that DNA is the molecule responsible for inheritance, challenging the previously held view that proteins did this job due to their complexity. The structure of DNA as a double helix, revealed by Watson and Crick, consists of two strands formed by nucleotides. Each nucleotide contains one of four bases—adenine, thymine, guanine, or cytosine—conforming to the base pairing rule where adenine pairs with thymine, and guanine with cytosine. The sugar and phosphate groups form the backbone of each strand with the bases connecting in the middle via hydrogen bonds. The discovery of enzymes that can manipulate DNA—cutting and copying sections—was another significant advance, highlighting DNA's central role in biology.
Research by scientists such as Hershey and Chase, as well as Erwin Chargaff's ratio rule, provided evidence that DNA, not proteins, carries genetic information. The understanding that DNA's structure allows it to store vast amounts of information in the sequence of its four bases revolutionized the field of genetics and cemented DNA's role as our hereditary material.