 A non-living thing  A nucleic acid surrounded by a protein coat  Doesn’t grow, respond, eat, or possess cells  A tiny disease-causing structure › 10,000 cold viruses fit on a period on this page.  Requires a host to live and reproduce

 Since they are non-living, they are not placed in a biological category.  Instead, scientists organize viruses in their own non-living category. › Shape (next slide) › Type of nucleic acid contained (RNA or DNA) › Type of organisms infected › Presence or absence of viral envelope

Capsid : outer layer of all viruses; made of proteins

 Active Virus › Immediate infection › Symptoms within 1 to 4 days › Example: cold and flu viruses › Reproduce by the lytic cycle  Latent Virus › Can remain dormant for months or years › Symptomless › Example: herpes virus › Reproduce by the lysogenic cycle; enters lytic cycle when activated

1) ATTACHMENT : A specific virus attaches to the surface of a specific cell 2) INVADE : The nucleic acid (DNA or RNA) of the virus is injected into the cell. 3) COPY : The viral nucleic acid takes control of the cell and begins to make new virus particles. 4) RELEASE : The cell bursts open, hundreds of new virus particles are released from the cell. These virus particles go on to infect other cells.

 Coronavirus › Classification:  Family: Coronaviridae  Genus: Coronavirus  Species: Common cold virus › Structure:  RNA, helical, with envelope

 Acute infection with symptoms  symptomless period  reactivation of disease  Symptoms of reactivation may be different from original infection  No measurable viral particles during symptomless period

 Herpesvirus › Classification:  Family: Herpesviridae  Genus: Herpesvirus  Species: Simplex type 1 and type 2 › Structure:  DNA, helical, with envelope

 Chickenpox (Varicella) › Symptoms: Blister-like rash on surface of skin and mucous membranes. Blisters usually appear first on trunk and face, then spread to almost everywhere else.  Shingles (2 nd occurrence) › Symptoms: Rash occurs in an area of the skin that is supplied by the sensory fibers of a single nerve- dermatome. Rash appears as well-defined band on one side of body, or on one side of face, arms or legs.

 Definition: Mixture of live, modified, or dead viruses (or their toxins) which when administered into the body stimulates the body’s immune system to produce antigen-specific antibodies  Goal: Future exposure to the virus will trigger a ready response from the body. Specific antibodies will already exist to stop the infection.

 Results in new virus strains (example: influenza)  Requires new vaccines needed annually  In segmented viruses  Simultaneous infection of one cell with 2 different types of viruses leads to exchange of genetic information

 Background : You are hanging out with a group of friends at Sonic. Everyone gets a different drink, and you all take a sip. › Take a test tube. › Exchange #1: Find a friend. Fill your own pipette. Simultaneously release your pipette into your friend’s test tube. › Exchange #2: Find another friend and repeat. › Exchange #3: Find another friend and repeat. › Exchange #4: Find another friend and repeat. › Test your fluid. Did you catch a virus while sharing drinks? If your fluid is pink, then you are infected! › Circle your number on the board if you are infected.

 Starts in L.A. with 9 people…