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DNA replication: the first experiment


DNA replication
Sydney Brenner Scientist
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DNA replication was in the hands of the biochemists, and they thought it was very straightforward, you just have an enzyme called DNA polymerase, which Arthur Kornberg had worked on and discovered, and you had DNA and you gave it some substrates and so you had the equation DNA plus DNA polymerase plus four triphosphates gives you more DNA. And that was the end of the story as far as the biochemists were concerned. But we were interested in... not in just copying DNA, but how this DNA would be segregated, given to daughter cells. Would you have to copy the DNA from many sites, which is what the biochemists had at least a picture of? And how would you regulate this? Because a bacterial cell copies DNA exactly once; takes the daughters, and segregates them to different cells. So our idea was that DNA replication started at one place. So that we had an element which later became the origin of replication. And that there was what we called positive regulation. Namely something had to appear which said start here and go on doing it. Now, the concept then was that it wouldn't matter about what DNA was attached to that unit, it would be just copied. As you… as you can see that later that became the whole basis of genetic engineering, because if a bacterial DNA could, so to speak, identify its own DNA as opposed to anything else you put into it, then that would have made all of this impossible, but we took the view DNA is DNA, it's just bases, and if you attach it to the right replication unit, then it will be copied willy-nilly and wouldn't require subsequent elements within it. And we proposed to test our hypothesis of positive regulation by a whole series of experiments, of which the very first one worked.

South African Sydney Brenner (1927-2019) was awarded the Nobel Prize in Physiology or Medicine in 2002. His joint discovery of messenger RNA, and, in more recent years, his development of gene cloning, sequencing and manipulation techniques along with his work for the Human Genome Project have led to his standing as a pioneer in the field of genetics and molecular biology.

Listeners: Lewis Wolpert

Lewis Wolpert is Professor of Biology as Applied to Medicine in the Department of Anatomy and Developmental Biology of University College, London. His research interests are in the mechanisms involved in the development of the embryo. He was originally trained as a civil engineer in South Africa but changed to research in cell biology at King's College, London in 1955. He was made a Fellow of the Royal Society in 1980 and awarded the CBE in 1990. He was made a Fellow of the Royal Society of Literature in 1999. He has presented science on both radio and TV and for five years was Chairman of the Committee for the Public Understanding of Science.



Listen to Lewis Wolpert at Web of Stories



Tags: Arthur Kornberg

Duration: 2 minutes, 40 seconds

Date story recorded: April-May 1994

Date story went live: 24 January 2008