TAILIEUCHUNG - Lecture Biology: Chapter 16 - Niel Campbell, Jane Reece
Chapter 16 - The molecular basis of inheritance. The chapter describe the contributions of the following people: Griffith; Avery, McCary, and MacLeod; Hershey and Chase; Chargaff; Watson and Crick; Franklin; Meselson and Stahl; describe the structure of DNA; describe the process of DNA replication; include the following terms: antiparallel structure, DNA polymerase, leading strand, lagging strand, Okazaki fragments, DNA ligase, primer, primase, helicase, topoisomerase, single-strand binding proteins. | Chapter 16 The Molecular Basis of Inheritance Searching for the Genetic Material Evidence That DNA Can Transform Bacteria When T. H. Morgan’s group showed that genes are located on chromosomes, the two components of chromosomes— DNA and protein — became candidates for the genetic material. The discovery of the genetic role of DNA began with research by Frederick Griffith in 1928. Griffith worked with two strains of a bacterium, one pathogenic and one harmless. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings When Griffith mixed heat-killed remains of the pathogenic strain with living cells of the harmless strain, some living cells became pathogenic: R --> S transformation. Transformation, now defined as a change in genotype and phenotype due to assimilation of foreign DNA. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Living S cells (control) Living R cells (control) Heat-killed S cells (control) Mixture of heat-killed S cells and living R cells Mouse dies Mouse dies Mouse healthy Mouse healthy Living S cells RESULTS Griffith’s Experiment: Transformation Figure Can a genetic trait be transferred between different bacterial strains? In 1944, Oswald Avery, Maclyn McCarty, and Colin MacLeod announced that the transforming substance was DNA. Their conclusion was based on experimental evidence that only DNA worked in transforming harmless bacteria into pathogenic bacteria. Many biologists remained skeptical, mainly because little was known about DNA. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Avery, Macleod, McCarty Repeat Griffith’s Experiments Evidence That Viral DNA Can Program Cells More evidence for DNA as the genetic material came from studies of viruses that infect bacteria. Like many of today’s scientists, Hershey and Chase used such viruses, called bacteriophages (or phages), in their 1950’s molecular genetics research. Copyright © 2008 Pearson .
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