VIRUSES PA State Standards:

What are VIRUSES? 1) A nucleic acid (DNA or RNA) surrounded by a coat of protein. 2) Viruses are not considered to be alive (they are not in one of the five kingdoms).

Nonliving Properties of Viruses 1) Not made of Cells (no organelles or cell functions). 2) Can’t grow or reproduce on their own (reproduce inside the cells of other organisms). 3) Can be crystallized & stored for years.

Examples of Viruses: Bacteriophage Head Tail Capsid DNA Tail Fibers

Examples of Viruses: Influenza Virus Capsid RNA Protein spikes

What is a parasite An organism that attaches itself and feeds off of another organism. A parasite does harm to the organism it is attached to Hookworm

What is a host The organism that is harmed or hurt by the parasite Example: You are the host to a mosquito

Bacteriophage Reproductive Cycle

1- Attach Virus attaches to cell. Use tail to attach to cell membrane of cell. BacteriophageBacteria

2- Invade Viral DNA invades cell Virus injects nucleic acid into the cell. Viral DNA penetrates cell membrane/cell wall Viral DNA slides into host cell

3- Copy a) Virus’ nucleic acid attaches to DNA of the cell. Viral DNA Bacterial DNA

Bacteria is forced to make more & more viruses 3- Copy b) DNA copies and makes new viruses Virus takes control of cell & makes new virus particles.

4- Release Cell bursts releasing hundreds of new viruses

Bacteriophage Reproductive Cycle

5- VIRUSES & DISEASE 1) HUMANS a) Colds b) A.I.D.S. Aquired Immune Deficiency Syndrome H.I.V. – Human Immunodeficiency Virus

5- VIRUSES & DISEASE 1) HUMANS c) Polio Iron Lung F.D.R. Deformed Leg Caused by Polio

5- VIRUSES & DISEASE 2) ANIMALS Rabies

5- VIRUSES & DISEASE 3) PLANTS Tobacco Mosaic Virus

How are viruses transmitted? Direct contact Touching, body fluids, etc. Vectors - mosquitoes, flies, etc Airborne Spread by the air

Terms to know: What happens when a disease spreads fast in a certain area? An epidemic What system in your body is used to help stop you from getting sick? The immune system What is a small amount of a virus injected into your body to give you immunity called? A vaccine

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