Protozoa: Definition, Characteristics, and Types

Study Notes

Protozoa are a group of eukaryotic microorganisms that belong to the kingdom Protista.
They are single-celled organisms, usually microscopic, and can be found in almost every environment.
Protozoa are heterotrophic, meaning they obtain their energy by consuming other organisms or organic matter.

Amoebas (e.g., Amoeba proteus): characterized by their ability to change shape and move using pseudopodia.
Flagellates (e.g., Giardia lamblia): possess flagella, which are whip-like structures used for movement.
Ciliates (e.g., Paramecium caudatum): have cilia, which are short hair-like structures used for movement and sensing.
Sporozoa (e.g., Plasmodium falciparum): parasitic protozoa that form spores, often infecting animals and humans.

Cell membrane: semi-permeable membrane that surrounds the cell and regulates the exchange of materials.
Cytoplasm: jelly-like substance inside the cell membrane where metabolic processes occur.
Endoplasm: inner region of cytoplasm where organelles are found.
Ectoplasm: outer region of cytoplasm involved in movement and sensing.
Nucleus: contains genetic material and controls cell growth and reproduction.
Mitochondria: organelles responsible for generating energy through cellular respiration.

Holozoic nutrition: ingestion of solid particles or liquids.
Saprotrophic nutrition: absorption of nutrients from dead organic matter.
Osmotrophic nutrition: absorption of nutrients from the surrounding environment.
Aerobic respiration: energy production using oxygen.
Anaerobic respiration: energy production without oxygen.

Asexual reproduction: reproduction by binary fission, budding, or fragmentation.
Sexual reproduction: reproduction involving gamete formation and fusion.
Life cycle: varies among protozoa, but often includes stages such as trophozoite, cyst, and gamete.

Protozoa are eukaryotic microorganisms that belong to the kingdom Protista.
They are single-celled organisms, usually microscopic, and can be found in almost every environment.
Protozoa are heterotrophic, obtaining their energy by consuming other organisms or organic matter.

Amoebas are characterized by their ability to change shape and move using pseudopodia.
Flagellates possess flagella, whip-like structures used for movement.
Ciliates have cilia, short hair-like structures used for movement and sensing.
Sporozoa are parasitic protozoa that form spores, often infecting animals and humans.

The cell membrane is a semi-permeable membrane that surrounds the cell and regulates the exchange of materials.
Cytoplasm is a jelly-like substance inside the cell membrane where metabolic processes occur.
Endoplasm is the inner region of cytoplasm where organelles are found.
Ectoplasm is the outer region of cytoplasm involved in movement and sensing.

The nucleus contains genetic material and controls cell growth and reproduction.
Mitochondria are organelles responsible for generating energy through cellular respiration.

Holozoic nutrition involves the ingestion of solid particles or liquids.
Saprotrophic nutrition involves the absorption of nutrients from dead organic matter.
Osmotrophic nutrition involves the absorption of nutrients from the surrounding environment.

Asexual reproduction occurs through binary fission, budding, or fragmentation.
Sexual reproduction involves gamete formation and fusion.
The life cycle of protozoa varies, but often includes stages such as trophozoite, cyst, and gamete.