Protozoa

• Protozoa: are unicellular, eukaryotic, and heterotrophic organisms that, together with algae, are classified in the second kingdom of the Five-Kingdom System of Classification.
• The study of protozoa is called protozoology, and a person who studies protozoa is called a protozoologist.
• Protozoa: They are unicellular (single-celled), ranging in length from 3 to 2,000 micrometers. Most of them are free-living organisms, found in soil and water. More animal-like than plant-like.
• Protozoa: They possess a variety of eukaryotic structures and organelles.

  • Does not have CHLOROPHYLL.
  • They ingest whole algae, yeasts, bacteria, and smaller protozoans to get their needed nutrients.
• parasitic protozoa:

  • They break down and absorb nutrients from the body of the host in which they live.
  • Many of them are pathogens.
  • Some of them have a mutualistic symbiotic relationship
• Protozoa: do not have cell walls, but some, including some flagellates and some ciliates, possess a pellicle, which serves the same purpose as cell wall.
• Cytostome: Some flagellates and some ciliates ingest food through a primitive mouth or opening, called a cytostome.
• Paramecium: (common pond water cili- ates) which possesses both a pellicle and a cytostome. Some pond water protozoa (such as Amebae and Paramecium) contain an organelle called a contractile vacuole, which pumps water out of the cell.
• Vorticella:

  • (pond water ciliates)
  • have a contractile stalk. Within the stalk is a primitive muscle fiber called a myoneme
• Trophozoite & cytes: 1. A Motile Trophozoite Stage: motile, feeding, dividing stage in a protozoan's life cycle. 2. A Nonmotile Cyts Stage: is the nonmotile, dormant, survival stage. it is like bacterial spores.
• Protozoa are classified taxonomically by their mode of locomotion.

  • Some move by pseudopodia
  • flagella
  • cilia
  • and some are nonmotile.
• Amebae: move by means of cytoplasmic extensions called “pseudopodia”.
• Ameboid Movement: it is when an ameba first extends a pseudopodium in the direction the ameba intends to move, and then the rest of the cell slowly flows into it.
• Phagocytosis: it is when an ameba ingests a food particle (e.g., a yeast or bacterial cell) by surrounding the particle with pseudopodia, which then fuse.
• Food Vacuole (or phagosome): The ingested particle, surrounded by a membrane.
• Pinocytosis: When fluids are ingested in a similar manner.
• One medically important ameba is “Entamoeba histolytica”, which causes amebic dysentery and extraintestinal amebic abscesses.
• Ciliates:

  • it move about by means of large numbers of hairlike cilia on their surfaces.
  • it exhibit an oarlike motion.
  • ciliates are protists and love water.
  • it is the most complex of all protozoa.
• BALANTIDIUM COLI / B. Coli:

  • pathogenic ciliate, that causes dysentery in underdeveloped countries
  • it is usually transmitted to humans from drinking water that has been contaminated by swine feces.
  • it is the only ciliated protozoan that causes disease in humans.
  • Examples of pond water ciliates are Blepharisma, Didinium, Euplotes,
• Ciliates: methods of reproduction: METHOD OF ASEXUAL REPRODUCTION- Transverse fission: the cytoplasm separates transversely between two pairs of nuclei, forming two unrelated individuals. METHOD OF SEXUAL REPRODUCTION- Conjugation, is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells.
• Flagellated protozoa or Flagellates move using whiplike flagella. It exhibits a wavelike motion. Some flagellates are pathogenic.
• Non-motile (except for certain sex cells) bacteria are types of bacteria that don’t have the capabilities or physical makeup to move through their environment on their own. Methods of reproduction: -Asexual reproduction through multiple fission AND -Sexual reproduction through Flagellated sex cells