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- With 3D printing these days, you can literally download a file
off of the internet, and then build a physical object
out of it, and that's been revolutionary in a lot of aspects of life and science
and commerce, but biologists were starting to feel a little left out.
So they've been developing a way to kind of maybe download life,
like creating artificial life with DNA that was put together
using information on the Internet.
In a sense, it's the first living thing on the planet with a computer for a parent.
Now, if you're thinking of some kind of unholy monster grown in a vat,
you have to think a little smaller.
Actually, much smaller.
Back in 2010, a team of researchers in Maryland announced that they'd created a mycoplasma,
the smallest kind of bacteria and the smallest cell known to science
that can reproduce itself.
Picking something small was an obvious choice, because it's still hard for us
to make really big pieces of DNA, and smaller, simpler organisms
tend to have smaller genomes, the full set of DNA organized into genes
that stores the instructions that tell a living thing how to be alive.
Scientists have sequenced the mycoplasma's genome, meaning they know exactly what its genes look like
and what order they come in. And it only has about a million base pairs,
the chemical units of DNA that make up the genetic code.
Now, that might sound like a lot but it's not, especially when compared to the human genome,
which is more like three billion base pairs.
But even though the mycoplasma is pretty much as simple of a living thing
as it's possible to be, the biologists weren't able to create the entire thing on their own.
Now, a genome might contain all the information you need to make a cell,
but just the instructions aren't enough.
A cell is made of lots of things, including a membrane that separates it from the outside world.
Cell membranes and plenty of other cellular structures are still too complex for us to make in a lab.
So when scientists say that they've created an artificial organism,
what they mean is that they've downloaded its genome,
put that into a hollowed-out cell, and then convinced it to stay alive
using the synthetic genome for its instructions. But that took a lot of work.
The researchers needed to invent a way to assemble a one-million base pair sequence
of DNA from scratch, and they needed four different organisms to do it.
Well, five if you count the scientists themselves being humans.
First, there was mycoplasma mycoides,
the species whose genome they were trying to make.
They basically just used the published sequence of base pairs,
but they stuck a few watermarks in there, like a puzzle that translated to literature quotes,
the names of the researchers, and a way to contact them
if you solved the puzzle.
Now, the watermarks don't have any biological function,
but they would prove beyond any doubt that they'd really done it
and the DNA was artificial.
Then to put that huge piece of DNA together,
the team needed help from two lab favorites: baker's yeast and the bacterium, E. coli.
Now, inside of a cell, DNA is very stable, but outside of a cell, it's an incredibly long
and brittle molecule and sooner or later, it's bound to snap somewhere.
Fortunately, these bacteria and yeast are great at stitching together long pieces of DNA.
So the researchers started by taking the chemical compounds in DNA
and connecting them in the right order, making blocks of about 1,000 base pairs each.
Those blocks overlapped with each other just a little bit at each end,
so the bacteria and yeast cells putting them together would connect the right pieces.
So bacteria and yeast combine the blocks of 1,000 base pairs into chunks of 10,000,
and then 100,000 until they got the finished product: one piece of DNA a million base pairs long.
And finally, the researchers needed a cell to put the genome in.
So they got a closely-related species of mycoplasma, took out the DNA and used it as a sort of shell,
since it still had all the membranes and other complex cell parts in it.
What they got was a live colony of mycoplasma
whose genes had started out as digital information stored in a computer.
And even though it might sound like the beginning of a horror movie,
creating artificial life is changing how we think about chemistry.
With traditional genetic engineering,
where you splice new instructions into a naturally created genome,
we can only change things one gene at a time or two or three tops.
But with synthetic genomes, we can switch out dozens
or even hundreds of genes at once.
And life is really good at creating complex molecules.
The hope is that one day, we'll be able to change the genomes
of simple organisms like bacteria so they interpret their genes
as instructions to produce complex organic materials, like drugs or jet fuel.
And eventually, scientists will get to download
and create designer organisms on demand, like 3D printing for life.
Thank you for watching this episode of SciSchow,
and thanks especially to this episode's President of Space,
Ry Prindle, who would like to ask his favorite person in all of space
the appropriately named Alana Rose Purdy
if she would consent to marry and keep him
for all time and eternity,
which is just very sweet.
If you wanna help support this show,
you can go to patreon.com/scishow.
And don't forget to go to youtube.com/scishow and subscribe.
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