RENEE MONTAGNE, HOST:
And another Nobel Prize was awarded this morning.
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UNIDENTIFIED MAN: The Royal Swedish Academy of Sciences has decided to award the 2015 Nobel Prize in Chemistry jointly to Tomas Lindahl, Paul Modrich and Aziz Sancar for mechanistic studies of DNA repair.
MONTAGNE: And joining us to explain what DNA repair is all about is NPR science correspondent Joe Palca. And while it wasn't his big idea, winning a Nobel Prize usually involves somebody else's big idea or several people's big ideas. So, Joe, exactly how does DNA break?
JOE PALCA, BYLINE: Well, OK, Renee, so this is your morning lesson in molecular biology. I hope you've read the textbook last night 'cause that there's going to be a quiz later.
MONTAGNE: I've had my coffee (laughter). That's the best I could do.
PALCA: Yeah, OK. You remember that DNA is this amazing chemical molecule, really, and it's made up of this long strand of a backbone with these letters that connect to each other. So there's A, C, T, G - A goes with C, T goes with G. And if you think about it, there's three billion of these. And every time a cell divides, those three billion letters have to peel apart - each strand. You remember double-stranded DNA? One strand has one set of letters. The other stand has the other. So they have to come back together and repair - they have to match up again.
Well, what if an A mixes with a C or makes a mistake and mixes with the wrong letter? So mistakes happen. And the way you can think about this best as you know that game of telephone where I whisper in your ear and you turn around and whisper into somebody and somebody and you go down the line? By the end, the message can be pretty garbled. Well, if you don't have a repair mechanism in DNA, that's what happens - the message gets garbled. And so what these guys have done is come up with ways of repairing breaks that they know happen when the letters aren't transcribed properly.
MONTAGNE: And what did that turn out to be?
PALCA: Well, these are enzymes that are constantly being - they're sort of (laughter) they're watchdogs. They're sort of on the lookout for errors that are known to occur that they recognize and they say, oh, that didn't look right or there's something mismatched there or - they have specific names like base excision repair or nucleotide excision repair. But basically they're just looking for errors in the transcription process or errors in any kind of process that would make a mismatch of one of these letters and allow that mismatch to be propagated.
MONTAGNE: Well, it sounds like there have to be medical implications for this repair system.
PALCA: Right. So surely if the repairs don't occur then something can go wrong, and if that something is wrong in a particular way or in a particular gene, that's what can give rise to disease and to particular cancer. I mean, if once you start with an error mechanism - an error that gets into a cell, it can keep going forward and some of the breaks, for example, that would keep a cell from growing out of control might be taken off and it might start growing out of control.
MONTAGNE: Joe, give us a thumbnail - and I mean thumbnail - on the three winners.
PALCA: (Laughter) OK. Well, very briefly, Tomas Lindahl is a Swedish citizen who's now working in the U.K. Paul Modrich is an American who was trained at Stanford University and now is at Duke. And the third is Aziz Sancar, a Turkish citizen who came to the United States for his medical and research work and now he's working in the United States.
MONTAGNE: Thank you very much, NPR science correspondent Joe Palca, on news that the Nobel Prize for Chemistry was awarded today to three scientists for their studies of DNA repair. Transcript provided by NPR, Copyright NPR.