PATHOGENS

HOW DO PATHOGENS CAUSE DISEASE? EVIL SPIRITSSWAMP AIR IMBALANCE OF BODY FLUIDS

SCIENTISTS WHO STUDIED PATHOGENS 1860 LOUIS PASTEUR MICROORGANISMS AND GERM THEORY OF DISEASE JOSEPH LISTER SURGERY AND CARBOLIC ACID 1870’s ROBERT KOCH SPECIFIC MICROORGANISMS CAUSE SPECIFIC DISEASE 1880’s

TYPES OF PATHOGENS VIRUSES BACTERIA FUNGI PROTISTS

WHAT ARE VIRUSES? 1. Strand of hereditary material surrounded by a protein coating 2. don’t have a nucleus, cell membrane or other organelles 3. have a variety of shapes 4. too small to see with light microscope, discovered after invention of electron microscope

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DISEASES CAUSED BY VIRUSES COLD SORES MEASLES CHICKEN POX COLDS FLU AIDS

CHARACTERISTICS OF A VIRUS 1. Viruses are considered to be non-living ( they do not exhibit all criteria necessary for life) 2. do not have cells 3. do not carry out respiration 4. do not grow or develop 5. cannot live independently

STRUCTURE OF A VIRUS 1. inner core of nucleic acid, either RNA or DNA 2. outer protein coat called a capsid 3. arrangement of proteins in capsid determines the viruses’ 3-D shape that matches up with the shape of a molecule in the plasma membrane of the host cell (like interlocking puzzle pieces- this is how virus recognizes its host cell) 4. Some larger viruses have an envelope that surrounds the capsid

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ATTACHMENT AND INFECTION 1. viruses affect all 6 kingdoms 2. each virus has a specifically shaped attachment protein. 3. the virus and the place where it attaches must fit together exactly 4. some affect only one type of organism or part of an organism (example: potato leafroll 5. Can be carried to a plant’s surface by the wind or inhaled by an animal 6. rabies affects only mammals 7. viruses that affect bacteria are called bacteriophage 8. Bacteriophages attach to a bacterium and inject their hereditary material

REPLICATION- how do viruses multiply? 1. Since it is not a living organism it must be inside a host cell to reproduce 2. Once inside, it either becomes: a. active b. latent

ACTIVE VIRUSES A. Causes the host cell to make new viruses and destroys the host cell B. Reproduction steps: Attach (attaches to surface of the host cell) Invade (hereditary material attacks cell) Copy (hereditary material controls cell and makes copies) Release ( Cell bursts when “ _full_____ “ and virus infects other cells C. Examples: Common cold, flu/influenza

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Attach Invade Copy Release The Lytic Cycle

LATENT VIRUSES A. Virus enters the cell and becomes part of the cell’s hereditary material without destroying the cell or reproducing B. Can stay latent for years and then become active. It runs its course but never leaves the cell. C. Examples: hepatitis, herpes, HIV

FIGHTING VIRUSES 1. Vaccines are made from weakened or dead strains of the virus which allow the host to fight off some diseases 2. Famous First Vaccines –Edward Jenner 1796 developed first vaccine for smallpox –Jonas Salk 1955 developed polio vaccine

TREATING AND PREVENTING VIRAL DISEASE A. Antibiotics are only useful with bacteria B. Interferons are made by our bodies (natural defense against viruses) C. Antiviral drugs help fight or shorten the length of a virus

PUBLIC HEALTH MEASURES a. vaccinating people b. improving sanitary conditions c. quarantining patients d. Controlling animals that spread disease

GENE THERAPY 1. Placing of normal hereditary material enclosed in a virus inside of an infected cell. 2. The virus infects the “targeted cell” and takes over- “infecting” the body with normal hereditary material