Final answer:
The structure of DNA is known and was discovered in 1953 by James Watson and Francis Crick, who described it as a double helix with complementary base pairing, something we have known for many years thanks to significant contributions from previous research and technology.
Step-by-step explanation:
The statement that the actual structure of the DNA molecule is still unknown is false. The structure of DNA was discovered in 1953 by James Watson and Francis Crick, with key contributions from Rosalind Franklin's X-ray crystallography work. Watson and Crick proposed that DNA's structure is a double helix, in which two strands of nucleotide sequences coil around each other forming a spiral. These strands are held together by pairs of nitrogenous bases: adenine (A) with thymine (T) and cytosine (C) with guanine (G), known as Chargaff's rules. Moreover, the strands are complementary and anti-parallel, with one running in the 5' to 3' direction and the other in the 3' to 5' direction.
The discoveries leading to the determination of DNA as the carrier of genetic information include Erwin Chargaff's findings of base pairing regularities and the Hershey and Chase experiment, which showed DNA was the genetic material, not proteins. DNA replication happens before cell division and is semi-conservative because each new DNA molecule conserves one of the original strands and includes a new complementary strand.