Chapter 16 The molecular basis of inheritance

Chapter 16 The molecular basis of inheritance - Chapter 16-...

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DIES Living S cells found??? Chapter 16- The molecular basis of inheritance. Background: Watson and Crick proposed the double helical model for the structure of DNA (deoxyribonucleic acid). DNA is the substance of inheritance, and genes are composed of DNA on the 46 chromosomes. Nucleic acids are unique as they are able to replicate their monomers. Genes are on chromosomes: DNA or Proteins? A. DNA can transform bacteria. Using a form of the bacteria causing pneumonia: The living cells became pathogenic. Clearly some chemical component of the dead pathogenic cells caused the heritable change. This phenomenon is called transformation , a change in the genotype and phenotype due to the assimilation of external DNA. Avery purified various types of molecules from the heat killed Smooth cells, then tried to transform the living Rough cells with each type. Only DNA worked. Thus the transforming agent was DNA. B. Viral DNA can program cells. Viruses are a little more than DNA with a protective coat, (a simple protein). Viruses that infect bacteria are called bacteriophages or phages. Experiment using T2, a phage that infect E-coli: E. Coli multiplies cells, so when infected by T2, produces a group of T2. The protein of the phage did not enter the host cells. Since radioactivity was found in the bacterial cells(pellets) for the instance when the DNA was made radioactive, DNA from the phage entered the host cells. This evidence showed that DNA, rather than proteins, are the hereditary material, at least for viruses. C. DNA- Molecular diversity
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This note was uploaded on 04/20/2008 for the course BIOL 1010 taught by Professor Anafi/quinlan during the Fall '08 term at York University.

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Chapter 16 The molecular basis of inheritance - Chapter 16-...

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