Bacteria

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Bacteria Virus UnitViruses

• Unit II Spring Semester

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virus

• Sub cellular parasite
• Composed of protein coat nucleic acid core
  (remember Hershey Chase Experiment)
• No nucleus or cytoplasm
• Size 25nm to 250nm (1nm1X10-6mm)

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Shape of virus
www.kumc.edu/emrl/ laboratorystaffadvisorycommitt
ee.htm

• Spherical
• Cube or brick
• Needle shaped
• tadpole shaped
• bacteriophage

www.alteck.it/pagine/ alteck2_new.htm
ibmp.u-strasbg.fr/ dep_viro/BNYVV/
www.evergreen.edu/phage/
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www.sirinet.net/jgjohnso/ aboutviruses.html
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Bacteriophage diagram

micro.magnet.fsu.edu/ cells/virus.html
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Virus ability to cause disease

• Pathogen- virus that causes a disease
• Virulence- ability to to cause disease, how
  difficult the disease is to control
• In 1918 400,000 Americans died of the flu

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classification

• What type of nucleic acid they have
• Retrovirus (RNA core) virus (DNA core)
• Generally very specific about what they invade
• Bacteria virus (bacteriophage)
• Plant virus
• Animal virus
• Often specific down to the type of cell they will
  invade
• Ex polio only invades neural cell in the brain
  and spinal cord

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Method of transmission

• Wind
• Water
• Direct contact
• Transmitted by host
• Contact by waste
• Blood(body fluids) or sap

iccf-holland.org/kcc.html
helios.bto.ed.ac.uk/bto/ biology/imagmem3.htm
www.equinehospital.net/ Chest20wound.htm
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Types of Infection

• Lytic infection
• (lyse- rip open)

• Lysogenic infection
• (kinder gentler infection)

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http//biology.about.com/library/weekly/aa111600a.
htm
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Lysogenic Cycle
Viral genome reproduces with host genome
prophage
www.sirinet.net/jgjohnso/ aboutviruses.html
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http//biology.about.com/library/weekly/aa111600a.
htm
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History of the study of Viruses

• 1776 Jenner
• 1880s Pasteur
• 1892 Dimitri Iwanoski
• 1898 Martinus Beijernick
• 1935 Dr. Wendell Stanley

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Economic Importance of Viruses

• Good

• Bad