Viruses

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Viruses

• Life Science
• Mrs. Kerstetter

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What is a Virus?

• Virus
• small, nonliving particle that invades and
  then reproduces inside a living cell
• Viruses are NONLIVING!
• -not cells
• -do not use energy to grow
• -cannot respond to their surroundings
• -cannot make food, digest it, or produce wastes

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What is a Virus?

• Viruses can multiple, but NOT BY THEMSELVES!
• They need a HOST (living organisms to provide
  source of energy).
• Organisms that live on or in a host and cause
  harm to the host are called PARASITES.

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What is a Virus?

• Viruses can infect organisms in the following
  kingdoms
• Plant
• Animal
• Protist
• Eubacteria
• Archaebacteria
• Fungi
• ALL KINGDOMS (specific to species usually)

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Naming Viruses

• Do NOT use binomial nomenclature!
• Why not?!?
• Because viruses are not alive
• Name them by
• -disease they cause
• -organisms they infect
• -place where found
• -person who identified it

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Shapes and Sizes of Viruses

• Vary in size and shape
• -round, rod-shaped, bricklike, threadlike,
  bulletlike, many-sided
• -cannot be seen with our microscopes
• -so small they are measured in
• nanometers (nm)

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Bacteriophage

• Bacteriophage
• bacteria eater
• -have complex, robot-like shapes

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Structures of a Virus

• Two basic components
• 1. outer protein coat
• -protects the virus
• 2. Inner core of genetic material
• Protein coat has unique proteins that fit onto
  receptors on the hosts cell
• lock-and-key

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How Viruses Multiply

• 1st Virus attaches to cell
• 2nd virus enters cell
• 3rd virus genetic material takes over cells
  functions
• 4th cell produces VIRUS proteins and genetic
  material
• 5th genetic material and proteins made into new
  viruses

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How viruses attach to a host
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Active Viruses

• Active viruses go to work IMMEDIATELY after
  entering cell.
• Makes copy after copy of its genetic material
• Will BURST when full of viruses
• All of the viruses will now invade other cells

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Hidden (latent) Viruses

• Hide out in cell for awhile.
• After entering host, virus genetic material will
  become part of cells genetic material
• Will remain hidden for long or short periods
• Eg Cold sore virus

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Viral Diseases

• AIDS (Acquired Immuno-Deficiency Syndrome)
• Chicken Pox
• Influenza
• Measles
• Polio
• Rabies

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Viral Diseases

• Antiobiotics do NOT work for viral infections!
• Medicines can make you feel better or lessen
  symptoms.
• Vaccines help prevent the spread of viral
  diseases.

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Vaccines

• Vaccine
• substance that stimulates the body to produce
  antibodies to fight off the virus or bacteria
• Can be from dead virus/bacterium or from a
  weakened form of the virus/bacterium.
• What vaccinations have you received?