Viruses, Bacteria, Protists, and Fungi Chapter Seven: Viruses

Section 1: Viruses What is a Virus: Characteristics of Viruses Virus: a tiny, nonliving particle that invades and then multiplies inside a living cell The only way in which viruses are like organisms is that they can multiply Host: is a living thing that provides a source of energy for a virus or an organism Parasites: organisms that live on or in a host and cause it harm

Section 1: Viruses The Structure of Viruses Bacteriophage: is a virus that infects bacteria All viruses have tow basic parts: a protein coat that protects the virus and an inner core made of genetic material The virus’s genetic material contains the instructions for making new viruses Some viruses are also surrounded by an additional out membrane, or envelope

Section 1: Viruses The Structure of Viruses The proteins on the surface of a virus play an important role during the invasion of a host cell Each virus contains unique surface proteins The shape of the surface proteins allows the virus to attach to certain cells in the host What information does a virus’s genetic material contain?

Section 1: Viruses How Viruses Multiply Once inside a cell, a virus’s genetic material takes over many of the cell’s function. It instructs the cell to produce the virus’s proteins and genetic material. These proteins and genetic material then assemble into new viruses.

Section 1: Viruses Active Viruses A virus attaches to the surface of a bacterium The virus injects its genetic material into the bacterium The virus’s genetic material takes over the cell functions of the bacterium. The cell starts to produce the virus’s proteins and genetic material. Hidden Viruses A virus attaches to the surface of a bacterium The virus injects its genetic material into the bacterium The virus’s genetic material becomes part of the genetic material of the bacterium

Section 1: Viruses Active Virus The proteins and genetic material assemble into new viruses that fill the bacterium The bacterium bursts open, releasing new viruses. The viruses go on to infect more cells. Where in a host does a hidden virus “hide” while it is inactive? Hidden Virus After some time, the virus’s genetic material removes itself and becomes active The cell begins to produce the virus’s protein and genetic material, which assemble into new viruses The new viruses crowd the bacterium. Finally, the cell burst open and releases the new viruses

Section 1: Viruses Viruses and Disease Viruses can cause diseases in other organisms besides humans: ex: dogs get rabies The Spread of Viral Diseases Can be spread in different ways: by touching contaminated objects, bitten by an infected animal, cold or flu is past through the air from a person’s sneeze or cough, or contact with body fluids such as blood

Section 1: Viruses Viruses and Disease Treating Viral Disease There are no current cure for viral disease Many over the counter medications are available Resting, drinking plenty of fluids, and eating well-balanced meals may be all you can do while you recover from a viral disease

Section 1: Viruses Viruses and Diseases Preventing Viral Diseases An important tool that helps prevent the spread of viral diseases is vaccines Vaccine: is a substance introduced into the body to stimulate the production of chemicals that destroy specific disease causing viruses and organisms Another way to protect yourself against viral diseases is to keep your body healthy

Section 1: Viruses Closing Activity Students will draw tables to summarize this reproduction of active and hidden viruses, comparing the steps of each.