Viruses

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Viruses

• Latin for poison

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I. What is a Virus?

• A. Viruses are particles of nucleic acid (DNA or
  RNA single stranded or double stranded), encased
  in a protein (capsid), and in some cases lipids
  (envelope).

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• B. They come in all sorts of sizes but have one
  thing in common only reproduce by infecting a
  host cell using its parts to make more viruses.
  
• 1. Viruses are very specific only infect 1 type
  of cell and only 1 species. (host range)
• a. specific cell receptors (lock and key)

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• C. The best understood virus is the bacteriophage
  or phage virus, a virus that infects bacteria.
• 1. there are several different types of this
  phage, studying this allowed scientists to
  understand how viruses replicate.

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II. Viral InfectionA. Viruses can infect a cell
2 ways

• 1. Lytic Infection

• 2. Lysogenic Infection

• Virus enters a cell, makes copies of itself
  causes the cell to burst
• i. Virulent phage

• a. Virus integrates its DNA into the host cell,
  the viral genetic code (prophage) replicates
  along with the host cells DNA
• i. temperate phage

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III. Retroviruses

• A. Viruses that contain RNA as their genetic
  information are called retroviruses.
• 1. The RNA is then copied into DNA is joined
  with the host DNA (replicating backwards) with
  reverse transcriptase and is called a provirus.
• 2. Responsible for AIDs.

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IV. Are Viruses Alive?!
Characteristic Virus Cell
Structure DNA or RNA core, Capsid Cell membrane, cytoplasm, eukaryotes contain nucleus organelles
Reproduction Only within a host cell using the hosts transcription factors (obligate parasite) Independent cell division asexually or sexually
Genetic Code DNA or RNA DNA
Growth Development yes Yes in multicellular organism
Obtain/Use Energy No Yes
Response to Environment yes Yes
Change Over Time yes Yes

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V. Infectious Diseases

• A. Infectious diseases are ones you can catch
• Example flu, chicken pox, pneumonia
• B. When disease spreads
• 1. Endemic disease that exist permanently in a
  particular area or population. Ex malaria
• 2. Epidemic outbreak of disease that attacks
  many people at about the same time may spread
  through several communities (HOT ZONE area
  considered dangerous)
• 3. Pandemic epidemic spreads worldwide. Ex. HIV

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V. Infectious Diseases

• C. Ways disease spread
• People droplet infection, direct contact,
  indirect contact
• Patient Zero primary case
• Animals fleas, rats, ticks, mosquitoes
• Nonliving sources food, water

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VI. The C.D.C.

• A. The Center for Disease Control is responsible
  for trying to prevent deadly dangerous diseases
  from coming into your home.
• B. The CDC works with several disease researching
  them to find cures, vaccines other treatments,
  each disease falls under a different biosafety
  level 1-4 1 being the least dangerous

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VI. The C.D.C

• C. Levels of the C.D.C.
• 1. General lab safety equipment gloves, goggles
• 2. Level 1 plus face shield
• 3. Level 2 plus special mask coat
• 4. Special suit, separate air supply