Crispr Gene Editing Explained

By now, there's a good chance you've heard of CRISPR.

It's what scientists are using

to engineer seedless tomatoes,

monochromatic butterflies,

and even extra lean piglets.

CRISPR is essentially a find and replace function

for DNA, and in the hands of scientists,

it's a super powerful molecular tool

for rewriting the code of life.

So how does CRISPR work?

Imagine this little toy train track is your DNA.

And the genetic code that you want to swap out

is this bit right here.

So scientists design a short sequence of code,

called guide RNA that matches the bit you want to replace.

Then they attach the guide RNA to a protein called Cas9.

Together, they roam the cell's nucleus until they find

a matching piece of DNA.

Then they lock on, and go to work.

Cas9 unzips the DNA and slips in the guide RNA

to make sure it's a match.

If it is, Cas9 cuts the DNA in two.

Scientists can use this to snip out

a troublesome chunk of genetic code,

like say, a mutation that causes Huntington's Disease.

Then they can coax the cell to stitch in a new gene

where the old one used to be,

using the cells natural DNA repair machinery.

This is called gene editing

and it's exactly why CRISPR is such a big deal.

And scientists aren't the only ones using it.

Agricultural companies are designing crops

that are resistant to climate change,

super nutritious vegetables,

and even apples that don't turn brown.

Pharmaceutical firms are using it to develop

new classes of antibiotics and other life-saving medicines.

One day soon, doctors might even prescribe

CRISPR-based therapies that treat genetic diseases

like cystic fibrosis or sickle cell anemia.

And Cas9 isn't the only protein that works with CRISPR.

There's also Cas3, which gobbles up DNA Pacman-style

wherever it attaches.

And there's one called Sherlock,

which targets RNA instead of DNA,

and can sleuth out the presents of viruses.

Designer foods, animals, drugs,

these are just some of the ways

CRISPR has already changed biology forever.

But scientists are just beginning to explore

all that this technology might one day deliver,

good and bad.

The question now,

is how we keep this world-changing technology

from going off the rails.