11月10日CNN聽力：基因編纂邪術鉸剪手CRISPR 或祛除困擾人類遺傳惡疾
Your body contains 37.2 trillion cells.
And within each is a copy of a code consisting ofmore than 20,000 genes and billions of strands ofDNA.
This code is your genome and it determineseverything that makes you-you.
What if you could modify that code, bring backinstinct species, eliminate hereditary diseases?
That is precisely what molecular engineers and geneticists around the world are working on.
Genes are what we get and we're stuck with them.
The environment is the only thing we can change and there's kind of a limit of how much youcan do.
But now, if we can change our genes, too, really, in a much closer to total control of ourbiology and physiology.
George Church is one of many using a revolutionary gene editing technique called CRISPR-Cas9, which allows you to modify DNA sequences.
CRISPR is a way that you can design and target a particular part of your genome and changeit to something else.
Or you can delete a gene.
You can make all sorts of edits very precisely.
CRISPR is kind of like having to find, delete, replace function for DNA.
No one actually invented the process.
It happens naturally.
Scientists discovered that bacteria alter their DNA to defend against viruses,essentiallystoring part of the virus so they can identify, target and attack the virus if it comes back.
Researchers realize the tools bacteria use to do this were Cas proteins, nature's geneticscissors.
Geneticists are now using these proteins to make their own targeted changes to DNA.
This can be used in agriculture where you can change any plant or animal.
It can be used to eliminate invasive species.
What's most exciting about CRISPR is our ability to alter longstanding epidemics like malariaand HIV.
And that could potentially save millions of lives.
But CRISPR is not without controversy.
Consider what you can do with a person's DNA.
This past year, for the first time, scientists in China used CRISPR in an unsuccessful attemptto edit the genomes of human embryos.
People fear that CRISPR could lead to designer babies.
How do we prevent that from happening?
We shouldn't be playing. We should be engineering.
And I think that's what we are doing.
Where do you think the moral and ethical boundary is?
Safety. I think safety is number one.
Just like any new technology and new drug, we should try to make it as safe as possible.
At the intersection of fascinating and disgusting is this-it's a wall of gum, once listed as one ofthe germiest attractions in the world.
It's located in Seattle, Washington's Pike Place Market.
Legend has it that folks going to the theater there in the 1990s decided it'd be better to sticktheir gum on this brick wall than under their seats.
Twenty years and an estimated one million pieces later, it spread well beyond the original wall.
So, officials are spending about 4,000 to get it steam cleaned.
They do expect the gummy tradition to continue, just on a clean slate.
Plans for how to do the job are just brick-gumming.
It will be have to done piece by piece, brick by brick, grating your teeth and hoping you don'tget stuck.
And wall we can sit jaw about this all day, we've already gummed up the last part of our showand we don't have anymore time to stick around.
Our Carl Azuz for CNN Student chews.
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