Biology 1202B Chapter Notes - Chapter 12: Xeroderma Pigmentosum, Proofreading, Mitosis
25 Jul 2013
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Biology 1202b: chapter 12 dna structure, replication and organization. 1952 hershey & chase dna inherited material. 1953 watson, crick & franklin double helix dna structure. Tjio & levan 46 chromosomes in human nucleus. 1963 margit and sylvan nass mitochondrial dna. Transformation: the conversion of dna released by another cell"s breakdown. Studied bacteriophage t2; viruses infecting bacteria: virus: infectious agent containing dna/rna surrounded by a protein coat; uses cell"s resources. Phage replication cycle: phage attaches to bacterium"s surface and makes progeny (descendant) phages, t2 phage contained a dna core encapsulated by proteins. Protein (s-35) and dna (p-32) were tagged to 2 bacteriophages: no radioactivity in bacterial cells = easily measure material. If phages contained radioactive dna, bacteria was radioactive. Radioactivity was seen in progeny (replicated phage) phages (p-32) Established transformation; identifying dna was the hereditary molecule. Semiconservative replication: 2 parental strands separate and act as templates for new progeny synthesis of double-stranded dna molecules.
