Organised by the National Human Genome Research Institute each year, National DNA Day in the US on 25 April celebrates the discovery of DNA’s double helix in 1953 and the completion of the Human Genome Project in 2003. Here, we explore the history of DNA and its discovery’s unparalleled effect on science, medicine and the way we now understand the human body.

Discovering DNA’s structure

­Using the pictures that she had taken, Franklin was able to calculate the dimensions of the strands and found the phosphates were on the outside of the DNA helix.

 

Rosalind Franklin working in her lab. Image: Wikimedia Commons

Meanwhile, at the University of Cambridge, James Watson and Francis Crick deduced the double-helix structure of DNA, describing it as ‘two helical chains each coiled round the same axis’ following a right-handed helix containing phosphate diester groups joining β-D-deoxyribofuranose residues with 3’,5’ linkages.

The discoveries made by these scientists would propel the study of genetics into the modern science we know today. Crick and Watson were awarded the Nobel Prize for Physiology or Medicine alongside Maurice Wilkins, who worked with Rosalind Franklin, in 1962. You can read their original paper here.

Dolly the sheep

 

Dolly on display at the National Museum of Scotland, UK.

Dolly is arguably the most famous sheep in the world, having been the first mammal to be cloned from an adult cell. Born in 1996, Dolly was part of a series of experiments at the Roslin Institute in Edinburgh to create GM livestock that could be used in scientific experiments.

She was cloned using a technique called somatic cell nuclear transfer, where a cell nucleus from one adult is transferred into an unfertilised developing egg cell of another that has had its nucleus removed, which is then implanted into a surrogate mother.

The scientific legacy of Dolly the sheep. Video: Al Jazeera English

Dolly lived until 2003 when she was euthanised after contracting a form of lung cancer. Many speculated that Dolly’s early death was related to the cloning experiment but extensive health screening throughout Dolly’s life by the Roslin Institute suggest otherwise.

Her creation has led to further cloning projects and could be used in the future to preserve the populations of endangered or extinct species, and has led to significant developments in stem cell research.

In 2009, Spanish researchers announced the cloning of a Pyrenean ibex, which has been extinct since 2000, and was the first cloning of an extinct animal. Unfortunately, the ibex died shortly after birth but there have been a few successful stories since then.

The Human Genome Project

Beginning in 1990 and finishing in 2003, the Human Genome Project was an international research initiative that aimed to write the entire sequence of nucleotide base pairs that make up the human genome, including the mapping of all its genes that determine our physical and functional attributes.

The publicly funded $3bn project was able to map 99% of the human genome with 99.99% accuracy, which included its 3.2bn Mega-base pairs, 20,000 genes and 23 chromosome pairs, and has led to advancements in bioinformatics, personalised medicine and a deeper understanding of human evolution.