Video transcript: Epigenetics: Ri Christmas Advent Calendar 2013 Chromosome 11
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Video shows photos of scientists
Fatima Santos, The Babraham Institute
We, for a very long time, had thought that if we had found the secrets of DNA we could find the secrets of life, we would be able to know exactly everything about that human being because all the information should be encoded in the genome, it is the blue print of life. Unfortunately, we still don't know exactly how those four letters combinations make everything that we see around us.
Video shows a drawing of a chromosome
So DNA sequence, the genome, is not the whole answer and chromosome 11 has helped us to understand that there is something else besides the sequence of the bases on the DNA that is important for the expression of these genes. Now if we think about what happens when a child is born then you have one of these little arms that comes from the mother and one of these arms have come from the father. They come together and they have, in exactly in the same position, exactly the same genes. We usually always have two copies of the same gene and for the most part they are always both working. There are a few exceptions.
Video shows a computer illustration of a sequence of DNA
One of them is chromosome 11. One needs to be on and other needs to be off and the mechanism that makes this copy silent is what interests me. It is called an epigenetics mechanism. It's a way by which the sequence of the DNA that is there, although intact not changed, is just marked in a special way with what we call epigenetics marks, and those marks tell that sequence not to be read, not to be on. And that means that you can have exactly the same DNA in two cells, as we do, and the same sequence being expressed in one cell and not being expressed in another cell making those two cells different although they have exactly the same information and exactly the same blue print. What creates this opportunity is what we call epigenetics.
Video shows words and sentences in a book
If you think about that the DNA, all the bases of the DNA, as the letters in a book. If you have just the letters, if you have no punctuation marks, no spaces between the words you really don't know how to read that page. Without the emphasis, without the pauses when you read the text, you still cannot get the full meaning of what is going on so epigenetics gives a layer of understanding, of interpretation, of the underlying genetic code or genome that we all have. In the case of chromosome 11 it is quite obvious that it is important to have the epigenetics marks in the right place at the right time because it gives you a very serious syndrome if you don't. So there are some examples that seem to show that the environment can affect epigenetics marks in a quite enduring and long-term way.
Video shows people eating out at restaurants
One example is nutrition. So the abundance of food for a period of time can have a big influence in the expression of certain genes and that is usually controlled by epigenetic marks. This can then stay as a memory of that event and they can be passed on to our children and probably to our children's children as well. So chromosome 11 was, and is, a very important tool still to study how these epigenetic modifications can actually control the expression of genes and the future will tell where this will take us.
- Production: Joy Ng
- Music: Marc Lieberman, Majorie McCarty, National Cancer Institute, Science Museum London, Science and Society Picture Library
- Special thanks: Fatima Santos
Supported by BBSRC. © The Royal Insitution 2013.