MYCOVIRO - INTRO TO MYCOLOGY (I)

• MYCOLOGY - Refers to the study of fungi, which are eukaryotic organisms that evolved in tandem with the animal kingdom.
• Eukaryotic organism reproduced via mitosis : sperm (haploid) and egg cell that will fuse
• Polar Bud Scar – key characteristics of a fungal cell
• Most fungi are non-motile, possess a rigid cell wall (with chitin inside) and are non-photosynthetic (no chlorophyll)
• Each fungal cell has at least one nucleus (uninuclear microorganism) with a nuclear membrane, endoplasmic reticulum, mitochondria and secretory apparatus.
• Most fungi are obligate or facultative aerobes
• Facultative aerobes – may or may not require oxygen to survive
• Obligate – requires oxygen to survive
• Chemotrophic secretes enzymes that degrade a wide variety of organic substrates into soluble nutrients that are then passively absorbed or taken into the cell by active transport
• Bacteria also has enzymes which it is use to infect cell, for fungi chemicals or enzymes are used as a source of nutrition
• Polar Bud Scar - produced from a mother yeast cell when it undergoes a type of asexual reproduction known as budding, Once the daughter yeast cell detaches, it will leave a scar.
• Fungal cells have rigid cell wall external to the cytoplasmic membrane.
• Ergosterol - main component of the cytoplasmic membrane of fungi
• Cholesterol - main component of cytoplasmic membrane of mammalian cells
• Cytoplasmic membrane is made up of sterol (a type of lipid)
• Fungi are usually haploid in their DNA content, diploid nuclei are formed through nuclear fusion in the process of sexual reproduction
• Fungi cell wall does not contain peptidoglycan (unlike gram positive bacteria), glycerol, teichoic acid, or lipopolysaccharide. Instead, they contain complex polysaccharides (carbohydrates) such as mannans, glucans, and chitins as well as structural proteins.
• Bacteria – cell wall contain lipids
• Fungi – cell wall contain carbohydrates
• YEAST

  • single cells (unicellular) usually spherical to ellipsoidal (mistaken for rbc/wbc > to identify, you can see the budding characteristics) in shape and varying in diameter from 3-15um
  • unicellular; creamy resembling bacterial colony; fungal cell
• MOLDS

  • Grows as filamentous(branching), tube-like structures called hyphae that vary in diameter from 2-10um.
  • multicellular; with cottony mycelial mass
• Hyphae is the root-like or rod like structures that are unique to molds.
• group or mass of hyphae forms the mycelia.
• YEAST STRUCTURE: Mostly unicellular and existing with buds growing on them
• MOLDS STRUCTURE Multicellular with tubular filamentous hyphae (branches)
• YEAST APPEARANCE Round or oval- shaped
• MOLD APPEARANCE

  Threadlike
• YEAST METHOD OF REPORDUCTION Budding or binary fission (rare)
• MOLD METHOD OF REPRODUCTION

  Production of sexual or asexual spores
• Vegetative Hyphae: Penetrates the media and absorbs food (they are like roots)
• Aerial hyphae: Directed above the surface of the media
• Reproductive hyphae: aerial hyphae that carries reproductive spores (they are like pollen in plants, once spores are inhaled, transferred to another media they can reproduce depending on their location )
• Septate – with cross walls / septa (septated hyphae)
• aseptate – without cross wall
• hyaline – transparent hyphae (no color because it will absorb the stain)
• Dematiaceous – pigmented hyphae (with color)
• Thallus – vegatative part; absorbs water and nutrients (roots)
• Aerial – reproductive part contains the fruiting bodies that produce the reproductive structures known as CONIDIA or SPORES
• VARIABLE FUNGI

  • MOST DEADLY TO HUMANS
  • Fungi that can transition between yeast – like and hyphal (molds) morphologies
  • Variation of shape is directly related to pathogenesis since different forms may be better suited for different microenvironments
• yeast can survive at optimum temperature of 37 C, while molds has optimum temperature of 20-25C (RT)