Until the early 19 fifties, the structure of DNA remained a mystery.

At Cambridge University, Francis Crick and James Watson worked on making physical models of what DNA may look like.

Meanwhile, at King's College in London, Maurice Wilkins and Rosalind Franklin were also studying DNA by examining X rated fraction images of DNA.

In short, this means that when shining X rays through DNA molecules, the X rays made a shadow of the molecule structure.

Over time, different researchers made important but seemingly unconnected findings about the composition of DNA.

For example, Alexander Todd discovered that the backbone of the DNA molecule contained repeating phosphate and dioxide arrivals.

Sugar groups.

Linus Pauling discovered the single stranded Alfa helix, prompting biologists to think of helical forms.

He also pioneered the method of model building in chemistry.

Maurice Wilkins and Rosalind Franklin had obtained high resolution X ray images of DNA fibers.

It suggested a helical, corkscrew like shape.

Franklin suspected that all DNA was helical.

Phoebus, Levene and others discovered that DNA was composed of subunits called nucleotides.

A nucleotide is made up of a sugar ah phosphate group and one of four nitrogenous bases.

Thes are eight and nine Thing I mean guanine and cytosine.

Um Irwin charge off had found that 89 timing always appeared in ratios of 1 to 1, as did guanine and cytosine.

In the end, it was Watson and Crick who eventually unified all these findings to reveal DNA structure.

They used pollings method of model building in chemistry to uncover the structure of DNA, Franklin's double helix idea and char gaffes.

Findings about base pairs were incorporated into Watson and Crick's model.

This meant that matching base pairs interlocked in the middle of the double helix to keep the distance between the latter legs or backbones constant.

Finally, Watson and Crick realized that they always paired with tea and likewise see with G.

The base is connected to the two helical sugar phosphate backbones of DNA at right angles, so the legs retained their regular double helix shape.

Similarly, the complementary pairing of the base is meant that the backbones ran in opposite direction to each other, one up the other down.

And so Watson and Crick showed that each strand of the DNA molecule was a template for the other.

During cell division, the two strands separate and on each strand and new other half is built.

This'll DNA can reproduce itself without changing its structure.

This discovery opened many doors and biological research.