Short answers, pulled from the story.
Friedrich Miescher discovered DNA in 1869 while examining pus from discarded surgical bandages. He named the substance nuclein and noted its presence within cell nuclei, though the scientific community initially dismissed it as a buffering agent.
Francis Crick and James Watson constructed the correct double helix model on the 28th of February 1953. Their findings were published in the 25th of April 1953 issue of Nature, following the critical X-ray diffraction data from Photo 51 taken by Rosalind Franklin in May 1952.
DNA is a polymer composed of two polynucleotide chains forming a double helix with a radius of 1 nanometer and a pitch of 3.4 nanometers. Adenine pairs with thymine via two hydrogen bonds, while cytosine pairs with guanine via three hydrogen bonds.
The human genome contains approximately 3 billion base pairs arranged into 46 chromosomes. Chromosome 1 is the largest at 220 million base pairs, and less than 10% of the human genome has a defined functional role.
DNA profiling was developed in 1984 by Sir Alec Jeffreys. The technique was first used to convict Colin Pitchfork in the 1988 Enderby murders case.
Ancient DNA has been recovered from extinct organisms up to millions of years old, such as the woolly mammoth. DNA survives in the environment for less than one million years before degrading.