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Transcript for Tom Cech Interview - Can you explain what the RNA world is?
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| Time | Content |
|---|---|
| 00:01 → 00:08 |
When scientists in the past have tried to think about what would be the simplest... |
| 00:08 → 00:17 |
...self-reproducing system, a primitive start to Life, they said: |
| 00:17 → 00:23 |
Well, this is a tough problem, because in order to have one generation... |
| 00:23 → 00:30 |
...provide the information to allow the next generation, which is very fundamental to Life, |
| 00:30 → 00:33 |
you have to have some kind of reproduction, |
| 00:33 → 00:38 |
you have to have offspring which can carry on the life form to the next generation, |
| 00:38 → 00:43 |
you need to have some kind of informational molecule... |
| 00:43 → 00:50 |
...and in our cells that’s DNA, the double helix that makes up the genes. |
| 00:50 → 00:54 |
But then, DNA by itself can’t do anything. |
| 00:54 → 01:02 |
Even just to copy it into daughter molecules of DNA, from the mother molecule, |
| 01:02 → 01:08 |
you need to have DNA polymerase, which is a very sophisticated protein enzyme. |
| 01:08 → 01:14 |
So the people who were theorizing about the origins of life... |
| 01:14 → 01:16 |
...were sort of stuck, because they said: |
| 01:16 → 01:22 |
It just seems very improbable that by random chemical processes... |
| 01:22 → 01:29 |
...in some small drop of liquid, you would get an informational molecule... |
| 01:29 → 01:34 |
...and a protein that could reproduce that informational molecule. |
| 01:34 → 01:39 |
DNA and a protein, by just random chemistry – seems unlikely. |
| 01:39 → 01:46 |
Now that we know that RNA can be both an informational molecule and a biocatalyst, |
| 01:46 → 01:54 |
and in fact it can do this sort of reaction of replicating, of taking one molecule and... |
| 01:54 → 01:59 |
...making another identical molecule to it, |
| 01:59 → 02:03 |
then maybe at the very beginning there was an RNA world. |
| 02:03 → 02:09 |
No DNA, no proteins, just RNA replicating itself. |
| 02:09 → 02:12 |
And then, as time went on, |
| 02:12 → 02:18 |
the RNA could catalyze the assembly of amino acids to make the proteins... |
| 02:18 → 02:23 |
...and now you can do a much wider range of biological catalysis. |
| 02:23 → 02:30 |
DNA is thought now to be a very recent invention. It’s not even that important. |
| 02:30 → 02:36 |
Simple systems, viruses for example, have RNA and protein - |
| 02:36 → 02:40 |
- many viruses don’t even have any DNA. |
| 02:40 → 02:43 |
They just use RNA as their informational molecule. |
| 02:43 → 02:51 |
So DNA is now thought of as being a relatively recent invention in Evolution, |
| 02:51 → 02:58 |
that allows larger genomes to be stable and it protects the genetic information. |