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Scientists are working on creating organisms with designer genomes -- and someday, we might end up with bacteria manufacturing our jet fuel.

Hosted by: Hank Green
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Sources:
http://www.sciencemag.org/content/329/5987/52.full
http://www.nature.com/news/2010/100520/full/news.2010.253.html
http://www.nature.com/nature/journal/v473/n7347/full/473403a.html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3580775/
http://www.genomebiology.com/2015/16/1/125
http://www.ted.com/talks/craig_venter_unveils_synthetic_life?language=en
http://genome.cshlp.org/content/14/2/221.long
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 kinda, 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 it's 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 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 solve 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 a thousand base pairs each.

Those blocks overlap with each other, just a little bit at each end, so the bacteria and yeast cells putting them together would connect the right pieces.

The bacteria and yeast combine the blocks of a thousand base pairs into chunks of ten thousand and then a hundred thousand, until they got a 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 could 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 SciShow, 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 Alannah Rose Purdie, if she would consent to marry and keep him for all time and eternity, which is just very sweet. 

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