VIRUSES!

Viruses Tiny NON-LIVING particle that enters and then reproduces inside a living cell. Considered to be NON-LIVING because they are not cells and cannot make or take in food.

Size of Viruses

Structure of a Virus All viruses have 2 basic parts: a protein coat that protects the virus and an inner core made of genetic material. Come in different shapes (but all have those 2 parts)

How Viruses Multiply Although viruses can multiply, they do so differently than organisms. Viruses can multiply ONLY when they are inside a living cell. Host: organism that provides a source of energy for a virus or another organism.

How Viruses Multiply 1. Virus attaches to a cell 2. Virus injects into genetic material 3. Virus’ genetic material takes over the cell’s functions. It instructs the cell to produce the virus’ proteins and genetic material. 4. The proteins and genetic material then assemble into new viruses. 5. The cell bursts and releases new viruses

Question to consider If a parasite is an organism that lives on or inside a host and causes it harm than…How are viruses different than parasites???

Virus Replication

Infectious Diseases Any disease that you can pass on to another person Spread by pathogens which are usually microscopic and impossible to see Spread by vectors, animals that do not actually get the disease, such as ticks, mosquitos, or rats

Viral Diseases Dangers: reproduce quickly, can alter original cell function Transmission: depends, some airborne, touch, or bodily fluids Examples: HIV/AIDS, Hepatitis, Flu, Cold, Chickenpox, Ebola, Cold sores Treatment: No cure for viruses, only vaccines which are preventative for some viruses

Epidemic When a large number of people in an area or community all become infected with the same disease Examples: (pick 2) Smallpox in the “New World” in 1500’s Flu of 1918 Swine flu of 2009

Pandemic An epidemic on a much larger scale, continent-wide or world-wide Examples: Black Death (bubonic plague) in 1600’s HIV/AIDS in Africa