(upbeat music) - [Narrator] Welcome to Liver Town!
A beautiful suburb, nestled in the Greater Body Metropolitan area.
(laughs) Here, each and every one of the 240 billion liver cells constantly work to keep their town healthy.
Work that is supervised by the Genetic Planning Authority and its two construction crews.
The go crew starts growth so the city can thrive.
And the stop crew stops growth so there's not overcrowding.
It is, all in all, a well-run, oh no!
It looks like there's trouble starting over there on lot 73A!
Oh, let's take a closer look to see what's going wrong.
When it's time for a cell to grow, the go crew gets to work.
Aw, but if the instructions are damaged, they don't know when to stop.
The cell grows out of control, and we could be watching the beginnings of cancer.
So, how do instructions get damaged?
Well, before it divides, each cell must carefully copy its DNA to pass to its daughter cell.
Usually, the cell makes an accurate copy.
But when six billion base pairs must be copied quickly, there's bound to be a few mistakes that slip through and bang!
That's not the only way mutations can occur.
Some happen from radiation like sunlight, or toxins like cigarette smoke.
(wheezes) Some mutations we inherit.
And some happen when the stop crew is broken.
And a damaged cell keeps splitting into more damaged cells, crowding neighbors, stealing resources, and making this once-beautiful town a dangerous place.
(gasps) So how do we fix all this?
Well, well one way is chemotherapy.
(explosion booms) That's like a nuclear strike that kills not only the bad cells, but a lot of the good cells, too.
A more strategic method is to read the broken DNA of a bad cell to determine a treatment that will only remove that cell.
Another is to read the whole body's genetic makeup to keep a lookout for any likely cancers, and treat it before any harm to this lovely, peaceful little town.
(chuckles) (gentle jazzy music)