BIOL 205 Chapter Notes - Chapter 7: Okazaki Fragments, Dna Clamp, Replisome
Document Summary
Griffith used strep pneumonaie in mice s strain=lethal, r strain + heat killed s strain is also lethal (first demo that genes are composed of dna) Hershey chase discovered that dna was the genetic material through t2 phage infecting e. coli and studying the resulting radioactivity. Chargaff said a=t and c=g and a+g=c+t (purines=pyrimidines) matched the model (radius of helix) that watson and crick later came up with. Rosalind franklin discovered the double helix via x-ray diffraction. Watson and crick 2 antiparallel strands held together by h-bonds between bases of each strand; backbone is alternating phosphate and deoxy sugar connected by phosphodiester bonds. Watson and crick also referred to semiconservative replication. Meselson and stahl used heavy 15n and cesium chloride gradient centrifugation to determine the semiconservative nature of dna replication; they looked at both first and second generation and their results were consistent with the semiconservative hypothesis. Dna polymerases: poly1 has 3 activities located in different parts of the molecule.
