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Chapter 9: DNA Structure and Analysis

Chapter 9: DNA Structure and Analysis. Honors Genetics Lemon Bay High School Ms. Susan Chabot. Fundamental Questions to Answer in this Chapter. How were we able to determine that DNA, and not some other molecule, serves as the genetic material in bacteria, bacteriophages, and eukaryotes?

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Chapter 9: DNA Structure and Analysis

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  1. Chapter 9:DNA Structure and Analysis Honors Genetics Lemon Bay High School Ms. Susan Chabot

  2. Fundamental Questions to Answer in this Chapter • How were we able to determine that DNA, and not some other molecule, serves as the genetic material in bacteria, bacteriophages, and eukaryotes? • How do we know that the structure of DNA is in the form of a right-handed double helical model? • How do we know that in DNA, G pairs with C and A pairs with T as complementary strands are formed? • How do we know that repetitive DNA sequences exists in eukaryotes?

  3. Four Characteristics of Genetic Material • Replication • Fundamental property of living things • Diploid to diploid in somatic cells • Diploid to haploid in gametic cells • Storage of Information • Repository of information even if not being used by the cell. • Expression of Information • Central Dogma of Biology • Variation by mutation • Provides the raw material for processes of evolution.

  4. Central Dogma/Information Flow DNA Transcription mRNA rRNA tRNA Ribosome Translation Protein

  5. Griffith Experiment and Transformation Used 2 strains (types) of Diplococcus pneumoniae. Smooth = virulent = dead Rough = avirulent = lives Heat killing the virulent form of the pathogen failed to produce disease. Mixing heat-killed smooth/virulent and living rough/avirulent DID kill mice after 5 days. Concluded that some “factor” was transferred from dead virulent strain to living avirulent strain and caused disease.

  6. Avery, McCarty, and MacCloud

  7. Hershey-Chase • Use of a phage; a virus that infects a bacteria. • Phage infects E. coli bacteria. • Phages are labeled with radioactive material. • Adhere to the phosphorus of the DNA molecule and the sulfur of the protein coat. • Because the protein coat of the phage remained OUTSIDE the bacterial cell, the protein was not involved in the production of new phages.

  8. DNA as Hereditary Material • Griffith, Avery et al, and Hershey-Chase experiments provided convincing evidence that DNA is the molecule responsible for heredity. Bozeman Biology Video

  9. RNA as Genetic Material in Some Viruses • Directs the production of all components necessary for viral reproduction. • Retroviruses use RNA as a template for the synthesis of a complementary DNA molecule. • HIV is a retrovirus

  10. Evidence Indirect Evidence • Distribution: should be found where it functions. • Mutagenesis: capable of being changed by mutagens. Direct Evidence • Recombinant DNA technology proved that DNA was the mechanism of heredity. • Ability to splice DNA from one organism into another producing a transgenic animal.

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