DNA contains the genetic code
found in all known life on our planet.
In each of nearly all of your roughly 30 trillion cells,
there are 6.4 billion letters of DNA.
It's powerful stuff.
If the DNA in all of your cells was used to store computer data,
it could hold the equivalent of all the digital data
we currently store on Earth.
I'm Paul Nurse,
and I've spent much of my working life
thinking about DNA,
in particular how it's copied and distributed
inside cells every time they divide.
I was awarded the Nobel Prize for this work in 2001.
Our understanding of deoxyribonucleic acid, or DNA,
has grown enormously since its discovery in the 19th century.
DNA was shown to be responsible for genetic inheritance in 1944.
Then, in 1953, its structure was revealed using X-rays.
And DNA turns out to be a stunningly elegant molecule.
What you're looking at is the original DNA model
currently on display in the Science Museum in London.
It shows two long chains of molecules
spiralling around each other in a double helix, like a twisted ladder.
The rungs are pairs of four chemicals
marked as A, G, C and T.
Determining the order of these chemicals - their sequence -
is known as sequencing.
Being able to describe the DNA sequence allows scientists
to identify important differences between individuals.
These unique differences have become the basis for what is known
as our DNA fingerprint.
The first ever recorded DNA fingerprint was made in 1984
by my friend Alec Jeffreys
at the University of Leicester.
Using DNA taken from his technician
Vicky Wilson,
he described not only which parts of her DNA came from her mother
and which from her father,
but also the unique genetic code she possessed -
one shared by no other human being.
DNA fingerprints can prove identity, how we are related and more.
DNA testing of hair, skin cells or blood found at crime scenes
is now the gold standard
for conviction - or exoneration - of suspects.
It has revolutionised the criminal justice system.
In 2000, the first draft human genome -
all the DNA needed to build a human being - was unveiled.
And with the ability to read genomes came new insights
into how the human body works and how we evolve.
Analysing DNA sequences has now reached the public
in the form of commercial genetic testing
by companies such as Ancestry and 23andMe.
By sending a saliva sample - and a fee, of course -
anyone can receive a report containing information
such as where their ancestors were from and who they are related to.
This ability to analyse DNA
has had a personal consequence for me.
It's a twist of fate that although I have a long career in genetics,
I never realised that my own family had a DNA secret.
When I was in my 50s,
I found out that the person I'd thought was my sister
was, in fact, my mother.
My parents - the people who raised me - were, in fact, my grandparents.
For a long time, the identity of my father remained a mystery.
But amazingly, now in my 70s,
recently it was possible to identify him through DNA testing.
Analysing DNA has also enabled scientists
to do many extraordinary things,
ranging from predicting genetic diseases
to studying extinct members of the human family, like Neanderthals,
and extinct animals like mammoths.
A new frontier in genetics is CRISPR, a gene-editing tool
that works like molecular scissors,
enabling scientists to cut and paste fragments of DNA within cells.
This means genetic diseases
such as haemophilia, muscular dystrophy and cancers,
in principle, might be "corrected" by editing the DNA of human embryos.
This has the potential to improve many people's lives,
though more research is still required because
like all new therapies, they have to be shown to be safe.
There are also questions that need to be answered
about making changes that can be passed on to future generations.
But societies have navigated the challenges
that come with new scientific technologies before.
DNA is the stuff of life.
It is inevitable that the more we research,
the more we will understand about ourselves and the living world,
and the more power we will have to change it.
All this work with DNA will give insights into human development,
allow us to study extinct species
and help doctors to treat diseases like cancer
with medicine better personalised
for everyone's unique genetic makeup.
And we are also starting to make new genetic materials,
creating new synthetic proteins that could be used, for example,
to help break down pollutants or to reduce greenhouse gases.
Seven decades after the structure of DNA was first revealed,
the DNA revolution continues to be exciting.
It shows no signs of slowing down.