أسئلة الثالثة بارا دمياط (قبل التعديل)

Protozoology

• Protozoa are unicellular eukaryotic organisms that can exist singly or in colonies.
• They belong to the Kingdom Protista.
• The single protozoan cell performs all necessary functions.

Morphology of Protozoa

• Trilaminar unit membrane: Forms the boundary of the protozoan cell.
• Cytoplasm: Comprises two layers:
  • Ectoplasm: The outer, hyaline layer, involved in locomotion, engulfing food (forming pseudopodia), respiration, waste removal, and providing protection.
  • Endoplasm: The inner granular layer, containing various structures like food vacuoles, Golgi bodies, contractile vacuoles, and endoplasmic reticulum. Contractile vacuoles help regulate osmotic pressure.

Nucleus

• The nucleus is the most crucial structure, regulating essential functions like reproduction and other vital processes.
• Nuclear membrane: Encloses the nucleus.
• Nuclear sap (nucleoplasm): The fluid within the nucleus.
• Chromatin granules: Contain the genetic material (DNA).
• Karyosome (nucleolus): A distinct DNA-containing body situated centrally or peripherally within the nucleus.

Biology of Protozoa

• Movement: Some protozoa move by pseudopodia, cilia, or flagella, while others do not move.
• Respiration: Protozoa may directly take in oxygen or use oxygen released from metabolic processes.
• Nutrition: Protozoa obtain nutrition by absorbing liquid food or ingesting solid material. Solid material is enveloped within pseudopodia or cytostome and becomes contained in food vacuoles. Digestive enzymes then process the food, and the waste is expelled either through the outer surface or via a special opening (cytopyge).
• Excretion: Protozoa excrete waste materials through osmotic pressure, contractile vacuoles, diffusion, or cytopyge.

Reproduction

• Protozoa reproduce asexually (simple binary fission, multiple fission – schizogony) or sexually (syngamy, fusion of two cells, one female (macrogamete) and one male (microgamete)).
• Simple binary fission: Individuals split into two organisms through longitudinal or transverse division.
• Multiple fission (schizogony): The nucleus undergoes multiple divisions preceding cytoplasmic division. This creates many smaller merozoites (or sporozoites) within the schizont. A good example of this is Plasmodium.
• Sexual reproduction (syngamy): Involves the fusion of two cells (one female and one male), which leads to microgametes and macrogametes (gametocytes, in some cases).

Classification of Protozoa

• Protozoa are categorized based on their movement methods (flagella, pseudopodia, cilia, or no movement), and often categorized as flagellates, sarcodina, sporozoa, or ciliates. Specific examples like Trypanosoma, Leishmania, Giardia, Trichomonas, Entamoeba, Plasmodium, Balantidium coli, etc. are classified within these groups, based on their movement and characteristics.

Life Cycle of Protozoa

• Simple life cycle: Protozoa with intestinal and luminal/urogenital life cycles often require just one host and reproduce asexually within that host. Transmission is normally direct.
• Complex life cycle: Most blood and tissue parasites pass between a vertebrate and an invertebrate host, thus undergoing an alternation of generations. Transmission is generally indirect. A good example presented is the comparison of Trichomonas and Malaria life cycles, highlighting the variations in transmission.

Questions

• Question 1: Protozoa belong to the kingdom Protista.
• Question 2: The protozoa that use pseudopodia for movement are Entamoeba.