replication of DNA and chromosomes

replication of DNA and chromosomes - Nature of the Genetic...

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Nature of the Genetic Material Property 1 - it must contain, in a stable form, information encoding the organism’s structure, function, development and reproduction Property 2 - it must replicate accurately so progeny cells have the same genetic makeup Property 3 - it must be capable of some variation (mutation) to permit evolution
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Historical Perspective 1928 - Griffith discovered a “transforming principle” in heat killed bacteria (Property 1) 1944 - Avery demonstrated that the transforming principle is sensitive to DNase 1952 - Hershey & Chase used 32 P and 35 S labelling, of bacteriophage T2 DNA and protein respectively, to show only the DNA enters the host cell and can be passed to progeny phage (consistent with Property 2)
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Replication of DNA and Chromosomes Speed of DNA replication: 3,000 nucleotides/min in human 30,000 nucleotides/min in E.coli Accuracy of DNA replication: Very precise (1 error/1,000,000,000 nt)
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Meselson and Stahl (1958)
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Taylor and co-workers (1957) 3 H-labelled chromosomes after one further replication in unlabelled media
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Bi-directional replication in E. coli
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Only One Replication Origin in E. coli
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replication of DNA and chromosomes - Nature of the Genetic...

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