Protozoa Structure and Function

Flagella of E.coli - Nicolle Rager Fuller, National Science Foundation

• Motile

• Protozoa possess all the 'usual' organelles which are found in most animal cells
  • Nucleus, endoplasmic reticulum, mitochondria, Golgi bodies and lysosomes

• Protozoa also possess other cellular structures, organelles and sub-cellular structures which enable an independent existence to be led

• Cilia
  • Fine, short hairs covering the protozoal surface each arising from a basal body
  • Hairs beat in unison to enable the protozoa to move
  • Wafts food towards the cytostome (mouth opening)
  • E.g. Balantidium

• Flagellum
  • Contractile fibre arising from a basal body
  • Contracts in a whip like motion to propel protozoa
  • Attached to body of some protozoa by an undulating membrane
  • During movement, the organism's shape is maintained by microtubules in the pellicle
  • E.g. Trypanosoma

• Pseudopodia
  • Extensions of the cellular cytoplasm
  • Cytoplasm flows into the pseudopodia allowing movement of the protozoa
  • Also acts in a phagocytic manner surrounding food particles and enclosing it in a vacuole
  • E.g. Entamoeba

• Gliding
  • No obvious means of locomotion
  • E.g. Eimeria