Pathogens: Viruses, Bacteria, Fungi & Protists

Pathogens: Viruses, Bacteria, Fungi & Protists

1. Viruses

   • Viruses range in size from about 20 to 400 nanometres in diameter.
   • Viruses reproduce inside a body cell and then destroy it when they burt out.
   • Viruses can affect your whole body, such as with an influenza virus, leaving you with all over muscle soreness and fever. Sometimes a virus can attack your nervous system causing serious illness.

2. What Are Pathogens?

   • Microorganisms that cause disease are called Pathogens
   • Bacteria can reproduce rapidly inside the body. They may produce toxins (poisons) that make up feel ill.
   • Viruses reproduce inside a body cell then destroy it when they burst out. The viruses then invade other cells.

3. Bacteria

   • Most bacteria are 0.2 um in diameter and 2-8 um in length. The three basic bacterial shapes are coccus (spherical), bacillus (rod-shaped), and spiral (twisted), however pleomorphic bacteria can assume several shapes.
   • Bacteria reproduce by binary fission. In this process the bacterium, which is a single cell, divides into two identical daughter cells. Binary fission begins when the DNA of the bacterium divides into two (replicates).
   • Bacterial infections disrupt the normal functions of the body and cause all kinds of illnesses. They injure the cells and tissues of the body, compromise the immune system, and deplete nutrients in the body.

4. Fungi

   • The sizes of fungi vary greatly depending on the type of fungus. In general, most microscopic—or smaller—fungi are 2 to 10 micrometers
   • The reproduction of fungi can be either sexual or asexual. Sexual reproduction, as with other organisms, involves the fusion of two nuclei when two sex cells unite. This joining produces spores that can grow into new organisms. However, the majority of fungi reproduce asexually.
   • Skin fungal infections thrive in warm, moist areas of the body, such as in the armpits or groin. ... Athlete's foot, yeast infections, jock itch, ringworm and some skin rashes are the result of certain types of fungi that can build up on the skin and mucus membranes to cause fungal infections.

5. Protists

   • The smallest protist. The smallest known free-living eukaryotes are marine picoplankton, of which the best-studied is Ostreococcus tauri. These organisms are so small (about 1 micrometer in diameter) that they are near the limit of resolution of ordinary light microscopes.
   • Protists can reproduce asexually through binary fission, one nucleus divides; multiple fission, many nuclei divide; and budding. During both types of fission the organism replicates its nucleus and divides to form new organisms. Budding occurs when a new organism grows from the body of its parent.
   • four basic types of protozoans afflict humans, which are classified in the groups Sarcodina, Mastigophora, Ciliophora and Sporozoa.

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