Answer:James Watson and Francis Crick
Explanation:
James Watson and Francis Crick with few other scientists proposed that DNA is made up of a double polynucleotide chains that are coil/twisted around each other to forming a helical structure. The two DNA chains runs anti-parallel in opposite direction to each other.
Each strand of the DNA is made up of long chain of nucleotides. Each nucleotide contains a sugars (D-ribose), a phosphate group and a nitrogen base forming the backbone of each DNA strand.
They are both DNA strands are held together by hydrogen bond between pairs of nitrogenous bases.
