Transcript Document
VIRUSES What kingdom are viruses found in?______________________ none Are they living or non-living? Explain. Non-living because they require a host to reproduce SBI3U 1 Some general information about viruses A Typical Virus •All viruses are ____________ and therefore require a nonliving host organism for its survival and continued reproduction. host range •Viruses only infect in their ___________________. •Viruses that infect bacteria are called capsid DNA ____________________. bacteriophage or phage •All viruses act by forcing the host cell to manufacture 100’s or 1000’s of copies of itself. While this is going on, the host cell can’t make the material it needs to carry sheath out its normal function – an _____________ infection results. If the infection spread locally an _____________ occurs, andepidemic if it travels globally it creates a ___________ . •Some viruses contain RNA instead of DNA. RNA viruses pandemic cause the more serious diseases. tail •Ex: DNA virus diseases_______________________ hepatitis B, cold sores, chicken pox, tumours, etc. •Ex. RNA virus diseases _______________________ SBI3U measles, mumps, polio, the cold, HIV, rabies 2 Phage reproduce either one of two ways: Lytic Cycle - the virus ___________________________________________________ completely destroys the host cell Lysogenic Cycle - the virus ___________________________________________ does not immediately destroy the host cell, virus enters a dormant state lysis TYPE A: Lytic Cycle - the host cell is completely destroyed (________________) - reproduction can occur rapidly (_________________) < 1 hour entire virus - In animal cells the _______________ enters the host 1. Phage attaches itself to host cell 2. Phage injects its DNA into the host 3. Phage DNA instructs host to make more phage DNA and capsids 4. New phage are assembled inside the host cell 5. Host cell fills with phage and fluid and bursts = lysis 6. Several hundred new phage are released and seek out uninfected cells SBI3U 3 TYPE B: Lysogenic Cycle - the host cell is not destroyed (lysed) immediately - viral DNA remains dormant inside host cell months to years - In animals, the entire virus remains dormant in the host cell for _______________ Ex. ______________________. Herpes, HIV 1. Phage attaches to host cell and injects DNA 2. Phage DNA becomes part of host cell’s DNA by recombination 3. Host cell reproduces normally and copies the phage DNA 4. Eventually phage DNA breaks away and instructs the cell to make new phage DNA and capsid 5. New phage form, cell lyses, phage are released. Review Define: Vaccination, Transduction, types of Gene Therapy, Viroids, Prions, BSE, CJD. SBI3U 4