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Lab. (3) the protozoa practical biology

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Lab. (3) the protozoa practical biology

The protozoa are the simplest and most primitive animals, usually defined as "unicellular" animals, the protozoa are classified into four classes on the basis of the structures they posses for locomotion:

  1. Class: Sarcodina: protozoa with locomotion by means of pseudopodia. Example: Amoeba

  2. Class: Mastigophora: protozoa with locomotion by means of flagella, this class divided into two types depending on method of feeding:

  1. Phytomastigophora like Euglena

  2. Zoomastigophora like Trypanosoma

3- Class: Sporozoa: parasitic protozoa without locomotion structure but move by gliding. Example Plasmodium

4- Class: Ciliate: protozoa with locomotion by means of cilia. Example paramecium

Class: Sarcodina

Genus: Amoeba

Amoeba is a genus of protozoa that moves by means of temporary projections called pseudopods, the amoeba is Greek word meaning (change).The most famous species, Amoeba proteus, is 700-800 μm in length but the species Amoeba dubia is as large as a millimeter, and visible to the naked eye. Amoeba eats algae, bacteria, other protozoan, and tiny particles of dead plant or animal matter and reproduce by a process called binary fission.

*The pseudopodia: is a part of the amoeba's body that it can stretch out and pull itself with. Or, to eat, the amoeba stretches out the pseudopodia, surrounds a piece of food.

Class: Ciliate

Genus: Paramecium

Paramecia are a group of unicellular ciliate protozoa, and range from about 50 to 350 μm in length, depending on species. Simple cilia cover the body, which allow the cell to move. They generally feed on bacteria and other small cells.

*Structure of Paramecium

Contractile vacuole (about to empty))


*Paramecium reproduction

Paramecium reproduces asexually by binary fission under ideal conditions, and reproduce sexually through a form of conjugation under stressful conditions.

Class: Mastigophora

Genus: Euglena

The Euglena is unicellular organisms called phytomastigina; it is holophytic, although it is able to live as a saprophyte. Some holophytic species of Euglena become holozoic when light levels are low. It reproduces asexually by longitudinal binary fission. The Euglena is able to move by using a flagellum, a long whip-like structure also by a contraction of its shape. this organism contain chloroplasts; green bodies containing chlorophyll (aids in carbohydrate synthesis), Food is not associated with the chloroplast, but is found in the cytoplasm in the form of a polysaccharide called paramylum granules (food reserve).

Paramylum granules

Class: Mastigophora

Genus: Trypanosoma

Trypanosoma are flagellate protozoa which live in the blood stream. There are several different species of Trypanosoma and they cause diseases. such as sleeping sickness, this parasite is transmitted by the bite of the tsetse fly (Glossina Genus) and reproduce by binary fission. The trypanosoma divided into two groups depended on method transmission of the infective stage

  1. Salivaria group: like T. brucei, this parasite transmitted by saliva of the tsetse fly.

  2. Sterocoraria group: like T.cruzi, this parasite transmitted by faeces of bed bugs.

*Structure the Trypomastigote form of Trypanosoma

* Diagnosis:

  • Clinical signs.

  • Trypanosomes found in blood.

  • Serological tests.

Class: Sporozoa

Toxoplasma gondii

Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii.

*Definitive host: cat

*Intermediate host: human and

other animals (herbivores, carnivores, omnivores).

* Morphology:

* Oocyst

The infective form of T. gondii, the oocyst is round to slightly oval. The transparent oocyst contains two sporocysts, each with four sporozoites. A clear and colorless, two-layered cell wall borders the organism.

*Tachyzoites (trophozoites)

Crescent-like and contains on centrally located nucleus, surrounded by a cell membrane .

*Bradyzoites (cyst)

The typical bradyzoite basically has the same appearance as the tachyzoite, only smaller in size, and form a cyst in a variety of host tissues and muscles outside of the intestinal tract.
*Laboratory diagnosis:

  • Oocyst in feces of final host.

  • Histological exams (cyst in tissue).

  • Immunological diagnosis ex. ELISA

*Life cycle:

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