W11VirusestoPost-1 - Lecture 7, February 1 Todays Outline...

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Lecture 7, February 1 Today’s Outline Viruses Characteristics (see next slide) Life cycle Influenza Announcements Exam Results 85.9% average Questions?--contact GSI first, then me Deadly Feasts P 113-168
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General Characteristics of Viruses Obligatory intracellular parasites Contain DNA or RNA Contain a protein coat Some are enclosed by an envelope Some viruses have spikes Most viruses infect only specific types of cells in one host Host range is determined by specific host attachment sites and cellular factors
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All Forms of Life have Viruses Bacterial viruses Plant viruses Animal viruses In the human body, nearly every system, tissue, and cell can be infected by one or more kinds of viruses
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Figure 13.1 Viruses are very small relative to eukaryotic and bacterial cells
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Non-enveloped Viruses Figure 13.2a Nucleic acid DNA or RNA Capsid Capsomeres (Protein coat)
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Capsids (shells) usually icosahedral symmetry or helical tube sometimes highly modified “bullet,” “cone,” often many copies of one or a small number of different proteins antigenic -- recognizable by immune response proteins on outer surface can interact with host cell surface proteins
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Figure 13.16a Polyhedral Viruses
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Figure 13.3 Morphology of an Enveloped Virus
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Envelopes surround the capsid made of membrane lipids (fats) richly studded with proteins antigenic Interact with host cell surface proteins fuse with cell membrane during infection
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Variety of shapes
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Viral genes Can be DNA or RNA Can be single or double stranded Can be linear or circular Genome is thousands of nucleotides long (millions for bacteria, billions for eukaryotes)
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Viral Receptors Usually proteins or parts of proteins on the outside of the virus (capsid or envelope) Fit some cellular surface molecule like a lock and key Interaction triggers a cellular response engulfment fusion Give the virus its primary host range
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In general. . A small number of genes Wrapped in a protective coat With “ receptors ” on the outside
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Life Cycle of Virus 1. Entry into a host cell 2. Production of new viral genetic material 3. Production of new viral genetic proteins 4. Assembly of new virus particles 5. Exit from the infected host cell
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1. Entry (viruses without envelopes) first must attach using receptors (specific) if a match, then engulfment -- looks like
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This note was uploaded on 02/17/2011 for the course BIOLOGY 118 taught by Professor Spillane during the Winter '10 term at University of Michigan.

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W11VirusestoPost-1 - Lecture 7, February 1 Todays Outline...

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