Lecture 2-1 - Lecture 1 - Genetics: DNA exchange 2/14/2011...

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Lecture 1 - Genetics: DNA exchange 2/14/2011 © Nicola Davies 2011 Genetics: DNA Exchange Lecture 1 February 14, 2011 2 The science of genes, heredity and variation in living organisms Genetic information stored the same way in all cellular organisms: Sequence of bases in DNA Replication and expression of genes essentially identical Modern molecular genetics dependent on bacteria Genes are not transferred exclusively vertically Horizontal gene transfer is common 3 DNA Exchange 5 Fundamental differences between prokaryotes and eukaryotes: 1. Prokaryotic reproduction never depends on genetic exchange 2. Exchanges usually small and futile 3. Random in nature but can be manipulated in the lab 4. Haploid genomes express recessive alleles 5. Eukaryotes use only fusion of gametes; prokaryotes use three methods of exchange 4 DNA Exchange in Prokaryotes Three methods: Transformation mediated by bacteria Transduction mediated by viruses Conjugation mediated by plasmids Each system is important in the lab Allow for transfer of recombinant DNA 5 DNA Exchange: Transduction Results from mistakes in packaging of bacteriophages Bacterial DNA partially or totally replaces phage DNA On subsequent infection, DNA will be transferred to new host 6 Generalized Transduction Salmonella and P22 are the best studied DNA replicated by rolling circle mechanism Long concatemers of ~ 10 phage genomes form Phage packed by “head - full” mechanism pac sites are present throughout genome Two phage-encoded proteins lead the DNA into the
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This note was uploaded on 11/17/2011 for the course BIO 456 taught by Professor Smith during the Spring '11 term at Aberystwyth University.

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Lecture 2-1 - Lecture 1 - Genetics: DNA exchange 2/14/2011...

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