1.4: Understand the Term Pathogen and Know that Pathogens May Include Fungi, Bacteria, Protoctists or Viruses

COMMON PATHOGENS
FUNGI s Both multicellular and unicellular Stores carbohydrates as Glycogen Organised into a Mycelium - threat-like structure called Hyphae that contains many Nuclei Feeds by extracellular secretion - the release of digestive enzymes onto food to absorb organic products (saprotrophic nutrition) Structure: Nucleus - membrane-bound organelle containing chromosomes Mitochondria - protein to carry out cell respiration  Cytoplasm - fills the cell to facilitate chemical reactions and holds organelles in place Cell membrane - phospholipid bilayer that controls movement of substances into and out of cell Example: Mucor / Yeast
BACTERIA s Unicellular organism Feeds on living or dead organisms Structure: Nucleoid - single circular strand of DNA Plasmid - independent small circle of DNA Plasma membrane - phospholipid bilayer that controls movement of substances into and out of cell  Cell wall - made of Peptidoglycan to protect and maintain shape of cell   *Pili - protein filmanets that facilitates cell adhesion and conjugation   *70S Ribosomes - site of protein synthesis   *Flagellum - elongated inflexible structure that rotates to move cell Example: Lactobacillus Bulgarcius (rod-shaped bacterium used in production of Yoghurt) Pnemococcus (spherical bacterium that causes Pneumonia)
PROTISTS s Microscopic unicellular organism Structure of protists are varied Example: Amoeba (animals) Chlorella (plants)
VIRUS s Non-living organism Parasitic as they can only reproduce inside living host cells Structure: Capsid - contains genetic material (DNA or RNA) Viral Envelope - made from fatty lipid molecules taken from host cells to avoid host immune system Surface Protein - proteins that help recognise and bind to host cells for infection Example: Tobacco Mosaic Virus (plant virus that causes discolouration of the leaves of tobacco plants) HIV (human virus that causes AIDS)