2WHAT IS A VIRUS?A tiny, NON-LIVING particle that enters and then reproduces inside a living cell.No organisms or cells are safe from viruses. All can be infected by a virus.
3Characteristics of Viruses Viruses are NON-LIVING because:They do not use their own energy to grow or respond to the environment.They cannot make food, eat food, or produce waste.
4Characteristics of Viruses Viruses can ONLY multiply inside of a living cell.A HOST is an organism that provides a source of energy for a virus or another organism.A PARASITE is an organism that lives on or in a host and causes it harm.
5Characteristics of Viruses A virus is a parasite because almost all viruses destroy the cell in which it multiplies. It causes the host harm and that is the definition of a parasite.
6Virus Shapes Some of the shapes of viruses are: round, rod-shaped, brick shaped, thread shaped, bullet shaped, robot shaped.
12Naming Viruses Scientists name viruses a number of ways: Named after the disease they causeNamed after the organisms they infectNamed after the place where it was first foundNamed after people
13The Structure of Viruses The 2 basic parts of a virus are:PROTEIN COAT that protects the virusINNER CORE made of genetic material (DNA)Some viruses are surrounded by an outer membrane or envelope.
14The Structure of Viruses The proteins in a virus help to invade the host cell.Viruses only connect to certain host cells because each virus has unique proteins that allow it to attach to only certain host cells. Its like a key (virus surface proteins) that only fit a certain lock (host cell surface proteins). Viruses won’t fit the lock on all host cells, only a specific few.
15The Structure of Viruses BRICKSHAPEDVIRUSHOST CELLKEYLOCKVirus surfaceproteinHost cell’s surface protein
17HOW VIRUSES MULTIPLYOnce a virus attaches to a host cell, it enters the cell.Once inside the host cell, the virus’s genetic material takes over the cell’s functions. It tells the cell to produce the virus’s proteins and genetic material so that more viruses can be made.
18Active VirusesOnce inside the host cell, an Active Virus starts taking over:The virus’s DNA takes over the cell’sfunctions2. The host cell makes more of the virus’s proteins and DNA3. New Viruses are made.4. This continues over and over again until…. The cellfills up with viruses and bursts.5. Hundreds of new viruses are free to find more cells.
20Hidden VirusesOnce inside the host cell, a Hidden virus hides for awhile inside the host:The virus’s DNA becomes part of the host cell’s DNAThe virus hides out, not doing anything sometimes for years.Every time the host cell divides, the virus’s DNA is copied along with the host cell’s DNAUnder certain circumstances, the virus’s DNA becomes active.Then the Hidden Virus becomes an Active Virus and does the same thing an Active Virus does.After an active period, it becomes a Hidden Virus again.
22Here’s a list of the Illnesses talked about in the book Chicken poxTobacco Mosaic VirusWest Nile diseaseRabiesSmallpoxCold SoreThe FluThe ColdYellow FeverStreptococcus (Strep Throat)PolioMononucleosisAIDSApple Mosaic VirusDistemperCystic Fibrosis