Viruses Indiana Science Text Pg Ebola Virus 1918 influenza virus

Virus Virus – Strand of DNA (hereditary material) surrounded by a protein coat. Virus – Strand of DNA (hereditary material) surrounded by a protein coat.

Virus Viruses – Living or Nonliving? Viruses – Living or Nonliving? Made up of cells? Made up of cells? Grow and develop? Grow and develop? Use Energy? Use Energy? Respond to surroundings? Respond to surroundings? Reproduce? Reproduce? NO NO NO NO YES NONLIVING

Virus Host – Living thing that provides a source of energy for a virus or organism. Host – Living thing that provides a source of energy for a virus or organism. Parasite – Organism that lives in or on a host and causes harm. Parasite – Organism that lives in or on a host and causes harm. Almost all viruses act like parasites because they must be inside a living cell to reproduce AND they destroy the cells in which they multiply. Almost all viruses act like parasites because they must be inside a living cell to reproduce AND they destroy the cells in which they multiply. Viruses vary in size, but all are much smaller than cells. Viruses vary in size, but all are much smaller than cells.

Virus Active Virus Active Virus Examples – cold, influenza (flu) Examples – cold, influenza (flu) After entering the cell, IMMEDIATELY goes into action After entering the cell, IMMEDIATELY goes into action Virus’s genetic material takes over cell’s function Virus’s genetic material takes over cell’s function

Active Virus 1. Virus attaches to cell 2. Injects genetic material into the cell 3. Cell produces virus’s proteins and genetic material 4. Parts assemble to form new viruses 5. Cell bursts when too full and release new viruses

Hidden Virus Hidden (latent) Virus  Example – cold sore  Doesn’t take action immediately

Hidden Virus 1. Virus attaches to a cell 2. Injects genetic material 3. Virus’s genetic material becomes part of cell’s genetic material. 4. Virus becomes active. 5. Cells produce virus’s proteins and genetic material 6. Parts assemble to make new viruses 7. Cell bursts – releases virus

Effects on other Organisms Most viruses attach to one kind of host cell Most viruses attach to one kind of host cell Viruses are transferred by Viruses are transferred by Air Air Objects Objects A virus that enters bacteria is called a bacteriophage. A virus that enters bacteria is called a bacteriophage.

Fighting Viruses A vaccine is weakened virus particles that helps you not to be infected by that virus. A vaccine is weakened virus particles that helps you not to be infected by that virus. The first vaccine was made in 1796 by Edward Jenner. It was created to fight smallpox. The first vaccine was made in 1796 by Edward Jenner. It was created to fight smallpox. Ways to treat a virus include: Ways to treat a virus include: Rest Rest Some medications – Antiviral medications Some medications – Antiviral medications

Research with viruses Viruses can be good. They are being used in gene therapy. Viruses can be good. They are being used in gene therapy. Some day, they may cure people with genetic disorders or cancer using virus to change DNA. Some day, they may cure people with genetic disorders or cancer using virus to change DNA.