1. Viruses
    Image 10.18A - An influenza virus
    Image 10.18A - An influenza virus
    1. What is a virus?
      1. A virus is a nonliving particle that requires a host cell in order to reproduce
    2. What are viruses composed of?
      1. Nucleic Acids
        1. DNA
        2. RNA
      2. Protein shell or coat known as a capsid
    3. Types of Viruses
      1. Bacteriophage
        1. Infect Bacteria
      2. Animal Virus
        1. Intect Animals
      3. Retrovirus
        1. Use the host cell to make DNA from RNA (known as reversetranscription)
    4. Shapes of Viruses
      1. Polyhedral
        1. Example: Flu
      2. Rod
        Image 10.18B - The reproductive cycle of an enveloped virus
        Image 10.18B - The reproductive cycle of an enveloped virus
      3. "Complex"
    5. Replication of Viruses
      1. Lytic Cycle (Virus Cycle)
        1. Attachment
        2. Entry
        3. Replication
        4. Assembly
        5. Release
      2. Some viruses lay dormant before reproducing
      3. Viruses have sitcky surfaces in order to get into host cells
      4. Viruses generally reproduce until the host cell is destroy or until it explodes from too many viruses
    6. Prevention of Viruses
      1. Vacines are the only help against viruses
        1. Vaccines are only for prevention and do nothing if the body already has the virus
        2. Vaccines are used to teach the body how to identify and defeat viruses
        3. A vaccine is a dose of something that contains a dead or weakened pathogen
      2. Edward Jenner
        1. The creator of vaccines
        2. He tested on his own baby son with the virus cowpox to prevent small pox
      3. Antibiotics - WILL NOT KILL VIRUSES because viruses are ambiguously alive
        1. Not alive
          1. Cannot reproduce on their own
          2. Need a host cell to reproduce
        2. Seem Alive
          1. Have DNA or RNA
          2. They kill their host
    7. Examples of Viruses
      1. Retrovirus
        1. Single strand of RNA
          1. HIV - Human Immuno-Deficiency Virus (NOT AIDS)
            1. You must have the HIV virus in order to get AIDS
          2. AIDS - Aquired Immune Defficiency Syndrome (NOT HIV)
        2. Use the enzyme Reverse Transcriptase (an enzyme to make DNA from RNA)
      2. Viral Infections include
        1. all colds and flu
        2. Most coughs
        3. Most sore throats
    8. Miscilaneous
      1. All viruses have some type of projection to get into host cell
      2. Viruses may have... (only can have one and only one form of genetic material)
        1. Double-Stranded DNA
        2. Double-Standed RNA
        3. Single-Stranded DNA
        4. Single-Stranded RNA
      3. Viruses tend to affect the entire body
        1. They do this because they travel through the blood stream
This video shows how HIV enters the cell and copies itself using reverse transcriptase.

Here are the five stages of the Lytic Cycle:
external image lytsum.gif