micropara

• Algae


  Photosynthetic, eukaryotic organisms
• Algal cells


  • Consist of cytoplasm, a cell wall (usually), a cell membrane, a nucleus, plastids, ribosomes, mitochondria, and Golgi bodies
  • Some have a pellicle, a stigma, and/or flagella
• Algae range in size

  • Unicellular microorganisms (e.g., diatoms)
  • Large, multi-cellular organisms (e.g., seaweeds or kelp)
• Algae

  • Produce energy by photosynthesis
  • Some may use organic nutrients
• Algae


  • Arranged in colonies or strands
  • Found in fresh and salt water, in wet soil, and on wet rocks
  • Most algal cell walls contain cellulose
• Algae classified by photosynthetic pigments

  • Green
  • Golden
  • Brown
  • Red
• Algae include

  • Diatoms
  • Dinoflagellates
  • Desmids
  • Spirogyra
  • Chlamydomonas
  • Volvox
  • Euglena
• Algae

  Important source of food, iodine, fertilizers, emulsifiers, and stabilizers and gelling agents for jams and culture media
• Prototheca


  A genus of algae that is a very rare cause of human infections, causing protothecosis
• Phycotoxins


  • Toxic substances secreted by algae in several genera, poisonous to humans, fish, and other animals
  • If ingested by humans, can lead to paralytic shellfish poisoning
• Protozoa


  Nonphotosynthetic, eukaryotic organisms
• Protozoa


  • Most are unicellular and free-living, found in soil and water
  • More animal-like than plant-like
  • Cannot make their own food, ingest whole algae, yeasts, bacteria, and smaller protozoa for nutrients
• Protozoa


  Do not have cell walls, but some possess a thickened cell membrane called a "pellicle" for protection
• Protozoan life cycle

  • Trophozoite (motile, feeding, dividing stage)
  • Cyst (nonmotile, dormant, survival stage)
• Some protozoa are parasites, causing many human diseases such as malaria, giardiasis, and trypanosomiasis
• Protozoa divided into groups based on locomotion

  • Amoebae (move by pseudopodia)
  • Ciliates (move by cilia)
  • Flagellates (move by flagella)
  • Sporozoa (no visible means of locomotion)
• Fungi


  • Diverse group of eukaryotic organisms that include yeasts, moulds, and fleshy fungi (e.g., mushrooms)
  • Not plants, not photosynthetic
• Fungi


  • Cell walls contain chitin
  • Some are unicellular, others grow as filaments called hyphae
  • Hyphae intertwine to form a mass called a mycelium
  • Some have septate hyphae (divided by cross walls), others have aseptate hyphae (no septa)
• Fungal reproduction

  • By budding, hyphal extension, or spore formation (sexual and asexual)
  • Fungal spores are very resistant structures
• Fungal phyla

  • Zygomycotina
  • Chytridiomycotina
  • Ascomycotina
  • Basidiomycotina
  • Deuteromycotina (Deuteromycetes)
• Deuteromycotina (Deuteromycetes)


  • Include medically important moulds such as Aspergillus and Penicillium
  • Have no known mode of sexual reproduction or the mode is not known
• Yeasts


  • Eukaryotic, unicellular organisms that lack mycelia
  • Reproduce by budding, occasionally by spore formation
  • Can form pseudohyphae (elongated buds)
  • Some produce chlamydospores (thick-walled, spore-like structures)
• Yeasts

  • Saccharomyces cerevisiae (used in baking)
  • Candida albicans (most frequently isolated from human clinical specimens)
• Differentiating yeast colonies from bacterial colonies

  • Yeasts are larger, oval-shaped, and observed budding
  • Bacteria do not bud
• Moulds


  • Produce cytoplasmic filaments called hyphae
  • Aerial hyphae extend above the surface, vegetative hyphae grow beneath the surface
  • Reproduce by spore formation, either sexually or asexually, on the aerial hyphae
• Moulds

  Have commercial importance - produce antibiotics, enzymes, and contribute flavour to cheeses