13. DNA structure

13. DNA structure - DNA Structure Genetic material-...

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Unformatted text preview: DNA Structure Genetic material- Patterns of inheritance can be explained by chromosome segregation- How do chromosomes transmit heritable traits? o Chromosomes made of proteins and DNA o Which molecule contains the genetic information?- There is a long history of experimentation to answer these questions Functions of genetic material- What does genetic material need to do? 1) Store information in stable, reliable form 2) Information must be readable 3) Information must be replicated 4) Information must be equally partitioned during cell division 5) Information must be able to change (evolution) but not too much Experimental work on genetic material: Griffith- Medical officer who did work on Streptococcus pneumoniae (1928)- He was actually looking for a vaccine against pneumonia- Found a clue about genetic material- Used two strains: smooth vs. rough o Smooth appearance: virulent strain Causes disease o Rough appearance: nonvirulent strain Harmless mutant (would not cause disease) Griffith experiment 1 Smooth bacteria (virulent strain) inject into mice o Mouse dies (no surprise) Conclusion: smooth strain is indeed virulent (control) Griffith experiment 2 Rough bacteria (nonvirulent strain) injected into mice o Mouse lives (no surprise) Conclusion: rough strain is indeed nonvirulent (control) + Griffith experiment 3 Smooth bacteria (heat kill) inject into mice o Mouse lives (no surprise): bacteria dead Conclusion: heat treatment kills bacteria (control) Griffith experiment 4 Heat kill smooth bacteria + mix with live rough bacteria => injected into mice o Mouse dies (big surprise): culture bacteria from dead mouse to find live smooth bacteria Conclusions- Does this show that DNA is the genetic material? NO.Does this show that DNA is the genetic material?...
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13. DNA structure - DNA Structure Genetic material-...

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