Chapter 12-1: Chapter 12-1: DNA: The DNA: The Genetic Material Genetic Material Section objectives: –Describe the experiments that showed that DNA is the genetic material. –List the three chemical parts of a DNA molecule. –Explain the Watson-Crick model of DNA. –Describe how DNA replicates in a living cell.
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Chapter 12-1:DNA: The Genetic Material Section objectives: –Describe the experiments that showed that DNA is the genetic material. –List the three chemical.
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Chapter 12-1:Chapter 12-1: DNA: The DNA: The Genetic MaterialGenetic Material
Section objectives:–Describe the experiments that showed that DNA is the genetic material.
–List the three chemical parts of a DNA molecule.
–Explain the Watson-Crick model of DNA.
–Describe how DNA replicates in a living cell.
History (tab 2)History (tab 2)
• 1869: Friedrch Miescher isolated material from nucleus of fish sperm. Called material nuclein.
HistoryHistory
• 1920’s, scientists found that chromosomes contained DNA.
• While chemical structure of proteins was well understood, DNA was not.–Many believed proteins carried
genetic info.
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HistoryHistory
• 1928: Frederick Griffith found that some factor from harmful, but dead bacteria could transform harmless bacteria into deadly bacteria.
Their exp’t Their exp’t conclusively conclusively showed DNA showed DNA to be the to be the genetic genetic material (not material (not proteins)proteins)
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The problem then became that of finding what DNA is made of and how it works!
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Composition of DNA (tab 3)Composition of DNA (tab 3)• 5-carbon sugar: deoxyribose5-carbon sugar: deoxyribose• A phosphate groupA phosphate group• 4 kinds of nitrogen-containing bases4 kinds of nitrogen-containing bases