Did you wash your hands today? Viruses Did you wash your hands today?

NOT LIVING – Not a cell (no membrane) Virus – What is it? NOT LIVING – Not a cell (no membrane) Particles of genetic material in a protein coat. (Either DNA or RNA inside a CAPSID.) One thing in common: They must enter a living cell and use its functions to make more viruses.

Several Shapes Influenza Hepatitus B Virus Rabies Virus HIV

Bacteriophage (bacteria attacker) Looks like a weird spider Example T4 Bacteriophage

Growth & Reproduction Cannot grow or make proteins by itself Must infect a host cell (Parasitic) Can reproduce by: Lytic Cycle Lysogenic Cycle

Lytic Cycle (causes cell to burst) The virus injects its DNA into a cell, and the cell makes copies of it. The cell uses proteins and viral DNA to make new viruses. The crowded cell bursts and new viruses are released.

Lysogenic Cycle A piece of viral DNA is inserted into the cell DNA and becomes part of it. When the cell DNA is copied, so is the viral DNA. The inserted viral DNA is called a PROPHAGE. The prophage may remain inactive a long time. When it activates new viruses are made and a lytic cycle begins.

Body Defenses & Treatments Skin…that’s it! Treatments Vaccines can prevent disease but not necessarily infection

Antibiotics Vs. Vaccine Antibiotics work against bacteria, but not viruses. Best defense against a virus is a vaccine. Example is the cold and flu (both are viruses)

Vaccines How do they work… 1. Weakened or killed pathogen is injected into the patient 2. The body’s defense system makes antibodies to fight the pathogen 3. The antibodies bind to the pathogen to neutralize it 4. Memory cells are produced to remember the pathogen if it infects again later and neutralize it again.