[BIO 1306] Ch13_Lecture

[BIO 1306] - 13 The Genetics of Viruses and Prokaryotes 13 The Genetics of Viruses and Prokaryotes 13.1 How Do Viruses Reproduce and Transmit Genes

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13 The Genetics of Viruses and Prokaryotes
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13 The Genetics of Viruses and Prokaryotes 13.1 How Do Viruses Reproduce and Transmit Genes? 13.2 How Is Gene Expression Regulated in Viruses? 13.3 How Do Prokaryotes Exchange Genes? 13.4 How Is Gene Expression Regulated in Prokaryotes? 13.5 What Have We Learned from the Sequencing of Prokaryotic Genomes?
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13.1 How Do Viruses Reproduce and Transmit Genes? Prokaryotes and viruses make good model organisms: Small genomes Reproduce quickly Usually haploid
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Figure 13.1 Model Organisms
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13.1 How Do Viruses Reproduce and Transmit Genes? Viruses are acellular . Most are composed only of nucleic acids and some proteins. Viruses do not: Regulate transport of materials into and out of themselves Perform any metabolic functions
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Table 13.1 Relative Sizes of Microorganisms
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13.1 How Do Viruses Reproduce and Transmit Genes? The first virus was discovered in the 1890s—it was an agent that causes tobacco mosaic disease. The “agent” could pass through a filter that retained bacteria, and could diffuse through an agar gel. The agent was crystallized in 1930s.
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13.1 How Do Viruses Reproduce and Transmit Genes? Viruses are obligate intracellular parasites . They use the host cell’s DNA replication and protein synthesis machinery to reproduce themselves.
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13.1 How Do Viruses Reproduce and Transmit Genes? Viruses outside the host cell are called virions . They consist of a central core of DNA or RNA, surrounded by a capsid of proteins. Viruses are not affected by antibiotics that target bacterial cell walls or ribosomes.
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13.1 How Do Viruses Reproduce and Transmit Genes? Classification: Genome of DNA or RNA Nucleic acid is single- or double-stranded Simple or complex shape Whether virion is surrounded by a membrane or not Type of organism it infects Manner of the infection
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Figure 13.2 Virions Come in Various Shapes
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13.1 How Do Viruses Reproduce and Transmit Genes? Viruses that infect bacteria are bacteriophage or phage . Phage binds to a receptor on the host cell wall, injects the nucleic acid, then one of two things happens:
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13.1 How Do Viruses Reproduce and Transmit Genes? Phage reproduces immediately and kills the host cell— lytic cycle —cell bursts and releases progeny viruses. Postpones reproduction by integrating into the host cell’s genome— lysogenic cycle .
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Figure 13.3 The Lytic and Lysogenic Cycles of Bacteriophage
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A virulent virus reproduces only by the lytic cycle. Early stage : The virus genome has a promoter that attracts host RNA polymerase. Viral genes adjacent to the promoter are transcribed. Products are proteins that shut down host
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This note was uploaded on 04/08/2008 for the course BIO 1306 taught by Professor Adair,tamarah during the Spring '08 term at Baylor.

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[BIO 1306] - 13 The Genetics of Viruses and Prokaryotes 13 The Genetics of Viruses and Prokaryotes 13.1 How Do Viruses Reproduce and Transmit Genes

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