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Chap 13 : DNA - Genetic Material

Chap 13 : DNA - Genetic Material. Finding the molecule…..the material must be… Able to store information that pertains to the development, structure and metabolic activities of the cell Stable so that it can be replicated Able to undergo changes ( mutations ).

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Chap 13 : DNA - Genetic Material

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  1. Chap 13: DNA - Genetic Material

  2. Finding the molecule…..the material must be… Able to store information that pertains to the development, structure and metabolic activities of the cell Stable so that it can be replicated Able to undergo changes (mutations) 13.1 – THE GENETIC MATERIAL

  3. 1869 – Discovering Nucleic Acids Swiss Physician, Johannes Friedrich Miescher isolated the chemical he called “nuclein” from the nuclei of pus cells Now called nucleic acids DNA (deoxyribonucleic acid) RNA (ribonucleic acid)

  4. NUCLEOTIDES (found in nuclein) Structure Sugar Phosphate Nitrogen base Adenine Guanine Cytosine Thymine

  5. THE BIG QUESTION Is it nucleic acidsor proteinsthat contain the genetic code? Proteins contain 20 amino acids that can be organized in countless ways to determine traits Nucleic acids only contains 4 different nucleotides

  6. TRANSFORMATION OF BACTERIA • Frederick Griffith attempted to find a vaccine against pneumococcus • He found that one type of bacteria could turn into another

  7. Figure 13.1a

  8. Figure 13.1b

  9. Figure 13.1c

  10. Figure 13.1d

  11. DNA WAS DETERMINED TO BE THE TRANSFORMING SUBSTANCE Conclusions: DNA from S strain bacteria causes R strain to be transformed Enzymes that degrade proteins will not stop the transformation Enzymes that degrade DNA does stop the transformation

  12. Alfred Hershey and Martha Chase Experiments

  13. Figure 13.2

  14. Figure 13.2a

  15. Figure 13.2b

  16. Bacteriophagesviruses that infect bacteria Consist of a protein capsid and a core of DNA (or RNA) Usedradioactive sulfur to tag the protein Used radioactive phosphorous to tag the DNA The goal was to see which substance (protein or DNA) moved into the infected cell

  17. Figure 13.3a Conclusion:  The radioactive tag on the DNA went into the bacteria

  18. Figure 13.3b Conclusion:  The radioactive tag on the protein did not go into the bacteria

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