Transmission genetics

Transmission genetics - o These R strained bacteria were...

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Transmission genetics – based on the extension and modification Molecular genetics What are genes made of? How doe genes work? Requirements for the hereditary material o Precisely duplicated and transmitted to the next generation o Serves as a system of information storage and retrieval 1944 o Avery, Macleod and McCarty at Rockefeller University o Demonstrated that the “transforming factor” in bacteria is DNA o Griffith’s transformation Experiment 1928 Griffith’s bacterial strains o S strain – virulent – form smooth colonies because cells have a polysaccharide capsule – can’t be phagocytized o R strain – a virulent – form rough colonies Transformation o Living s cells were obtained from the dead mice that had been rejected with dead S cells and living R cells o Conclusion – some substances from the dead S cells had been transferred to the living R cells and transformed them into S cells 1944 o Aver Macleod McCarty o Treated R strain bacteria with highly purified DNA groom S strain bacteria
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Unformatted text preview: o These R strained bacteria were then transformed into S strain bacteria • 1953 o James Watson and James crick proposed the double helix model of DNA structure • Components of DNA o 4 different kinds of bases (nitrogen containing rings) o Deoxyribose (sugar) o Phosphate AT (2 H bonds) GC (3 H bonds) • Complementary base pairing suggested the mechanism of DNA replication • Semi-conservative replication • DNA replication o Building blocks are nucleotides – unites consist of base deoxyribose sugar and 3 phosphates o When a new nucleotide is incorporated, two phosphates are released (exorgonic reaction) • Enzymes required o DNA polymerases – link the nucleotides together o Helicases – unwind the DNA o Topoisomerases – deal with knots and tangles • Additional complication o Each single DNA strand has its own polarity o The 2 strands of a double heloix are antiparralel to each other...
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