Protozoa: Sporozoates and Reproduction

Protozoa

• Protozoa are unicellular (may be multicellular) eukaryotic microorganisms that constitute a large group of about 65,000 species.
• Most protozoa are harmless, free-living, and inhabit water and soil, while a few species are pathogenic, parasitic, and cause hundreds of millions of infections worldwide.

Characteristics

• Protozoa are mostly unicellular organisms with fully functional cells.
• They are chemo-hetrotrops and have locomotive organelles such as flagella and cilia for movement.
• The cytoplasm of protozoa is divided into an outer layer (ectoplasm) and an inner layer (endoplasm).

Morphology

• Protozoa resemble animal cells and contain major cell organelles, including the nucleus and mitochondria.
• The size of protozoa ranges from 3 to 300 micrometers, and a few ciliate and amoeba species are large enough to be seen with the naked eye.
• Except for sporozoates, all types of protozoa are motile through flagella, cilia, or pseudopodia.
• Protozoa have eyespots that detect changes in light.

Nutrition

• Most protozoa feed on dead plants and animal debris, while some feed on bacteria and algae.
• Parasitic protozoa feed on the fluids and tissues of their host.
• Some protozoa live in symbiotic relationships with other plants and animals.

Classification of Protozoa

• Protozoa are classified into four main types based on their motility and method of reproduction: flagellates, ciliates, sarcodina, and sporozoates.

Types of Protozoa

Flagellates

• Flagellates move using flagella, which are whip-like structures.
• Examples of flagellates include Trypanosoma, Leishmania, Giardia, and Trichomonas.

Ciliates

• Ciliates move using cilia, which are fine hair-like structures.
• Most ciliates are harmless, except for Balantidium coli, which is pathogenic and causes dysentery.

Sarcodina

• Sarcodina have pseudopodia, which are false feet, as their major loco-motor organelles.
• Examples of sarcodina include Amoeba, which can be harmless or parasitic.

Sporozoates

• Sporozoates are the only non-motile form of protozoa.
• Examples of sporozoates include Plasmodium, which causes malaria.

Reproduction in Protozoa

• Protozoa can reproduce using both sexual and asexual methods.
• Asexual methods include budding, binary fission, and schizogony (multiple fission).
• Sexual methods include conjugation and gametogony.

Diseases Caused by Protozoa

• Examples of diseases caused by protozoa include malaria (Plasmodium), giardiasis (Giardia intestinalis), amoebic dysentery (Entamoeba histolytica), toxoplasmosis (Toxoplasma gondii), and leishmaniasis (Leishmania).

Antiprotozoal Drugs

• Examples of antiprotozoal drugs include chloroquine, mefloquine, and pyrimethamine, which are used to treat malaria.
• Metronidazole is an antiprotozoal drug that induces strand breaks in DNA and disrupts membrane integrity.
• Other antiprotozoal agents include sulphonamides and trimethoprim, which inhibit folic acid synthesis.

Learn about the characteristics of Sporozoates, a group of parasitic protozoa, and the different methods of reproduction in Protozoa, including sexual and asexual methods.