MICROPARA 5

• Algae


  Photosynthetic, eukaryotic organisms classified in the Protista kingdom
• Algal cells


  • Contain cytoplasm, cell wall, cell membrane, nucleus, plastids, ribosomes, mitochondria, Golgi bodies
  • Some have pellicle, stigma, flagella
• Algae are more plantlike than protozoa but lack true roots, stems, and leaves
• Algae range in size

  • Tiny, unicellular, microscopic organisms (e.g. diatoms, dinoflagellates, desmids)
  • Large, multicellular, plantlike seaweeds (e.g. kelp)
• Photosynthesis in algae


  Uses energy from the sun, carbon dioxide, water, and inorganic nutrients to build cellular material
• Most algal cell walls contain cellulose
• Algal pigments


  • Green
  • Golden (or golden brown)
  • Brown
  • Red
• Diatoms


  Tiny, usually unicellular algae with silicon dioxide cell walls, important members of phytoplankton
• Diatom uses


  • Diatomaceous earth for filtration, insulation, abrasives
• Green algae examples


  • Desmids
  • Spirogyra
  • Chlamydomonas
  • Volvox
  • Euglena
• Euglena


  • Possesses features of both algae (chloroplasts, photosynthesis, starch storage) and protozoa (cytostome, no cell wall)
  • Has stigma to sense light and flagellum to swim
• Some algae (e.g. Chlamydomonas, Euglena, Volvox) have characteristics that cause them to be classified as protozoa by some taxonomists
• Uses of algae


  • Food source
  • Iodine and other minerals
  • Fertilizers
  • Emulsifiers for pudding
  • Stabilizers for ice cream and salad dressings
  • Gelling agent for jams
  • Nutrient media for bacterial growth
  • Potential biofuel source
• Algae can cause damage by clogging filters and pipes if many nutrients are present
• Protothecosis


  Rare human infection caused by the alga Prototheca
• Protothecosis progression


  1. Prototheca enters wounds, especially on feet

  2. Produces small subcutaneous lesion that can progress to crusty, warty-looking lesion

  3. If enters lymphatic system, can cause debilitating, sometimes fatal infection in immunosuppressed individuals
• Algae in several genera secrete phycotoxins that are poisonous to humans, fish, and other animals
• Protozoa


  Eukaryotic organisms classified in the Protista kingdom, mostly unicellular and free-living
• Protozoal cells


  • Possess cell membranes, nuclei, endoplasmic reticulum, mitochondria, Golgi bodies, lysosomes, centrioles, food vacuoles
  • Some have pellicles, cytostomes, contractile vacuoles, pseudopodia, cilia, flagella
• Protozoa lack chlorophyll and cannot perform photosynthesis
• Protozoan nutrition


  • Some ingest algae, yeasts, bacteria, smaller protozoans
  • Others live on dead and decaying organic matter
• Protozoa lack cell walls but some have a pellicle for protection
• Cytostome


  Primitive mouth or opening in some flagellates and ciliates for ingesting food
• Paramecium


  • Possesses both a pellicle and a cytostome
• Contractile vacuole


  • Organelle in some protozoa that pumps water out of the cell
• Vorticella


  • Protozoan with a contractile stalk containing a primitive muscle fiber called a myoneme
• Protozoan life cycle


  • Trophozoite stage (motile, feeding, dividing)
  • Cyst stage (nonmotile, dormant, survival)
• Some protozoa are parasites that break down and absorb nutrients from the host
• Many parasitic protozoa are pathogens that cause diseases like malaria, giardiasis, African sleeping sickness, amebic dysentery
• Symbiotic protozoa


  Coexist with host in a mutually beneficial relationship, e.g. termites and their intestinal protozoa
• Protozoan locomotion types


  • Ameboid movement using pseudopodia
  • Ciliary movement using cilia
  • Flagellar movement using flagella
• Ameboid movement


  Cytoplasmic extensions called pseudopodia extend in the direction of movement, then the rest of the cell flows into it
• Phagocytosis


  Ameba ingests a food particle by surrounding it with pseudopodia that fuse together
• Pinocytosis


  Ameba ingests fluids in a similar manner to phagocytosis
• Entamoeba histolytica


  Ameba that causes amebic dysentery and extraintestinal abscesses
• Ciliates


  • Move using large numbers of hairlike cilia in an oarlike motion, most complex protozoa
• Balantidium coli


  Pathogenic ciliate that causes dysentery, transmitted from contaminated swine feces
• Pond water ciliates


  • Blepharisma, Didinium, Euplotes, Paramecium, Stentor, Vorticella
• Flagellates


  • Move using whiplike flagella with a wavelike motion, anchored by basal bodies
• Pathogenic flagellates


  Trypanosoma brucei (African sleeping sickness), Trypanosoma cruzi (Chagas disease), Trichomonas vaginalis (trichomoniasis), Giardia lamblia (giardiasis)