Anatomy Of Protozoan Cell


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  • Cell recognition: It has receptors for attachment with other cells through chemical signals. Secretion / Excretion: Responsible for secretion & excretion of various substances and these processes are similar to that of intake of material e.g. Trypanosomes excrete Trypanosin & oligopeptides to cross the blood brain barrier. Membrane bound structures exist for attachment / joining of cells e.g. fusion of gametes, places where flagella are attached. Flagella in trypanosomes are used to join with vector’s intestine.
  • Flagella & cilia are also called undulipoda. Flagella are whip like structure and composed of a central axoneme and outer sheath that originates from cell membrane. Axoneme consist of nine peripheral and one central pair of microtubules. Central tubules are singlets and peripheral are doublets. The axoneme originates from Kinetosome (basal body) and it lie in flagellar pockets. Complete unit of flagellum, kinetosome and associated organelles is called mastigont or a mastigont system. Some time flagellum bent back to form loosely attached structure cell surface known as undulating membrane. If Golgi body is connected by a parabasal filament to kinetosome it is known as Parabasal Body. A fibril that runs from kinetosome to nuclear membrane is called Rhizoplast. Entire complex of organelles and an associated nucleus is referred as Karyomastigont. Some flagellates (Kinetoplastida) have dark staining body of kinetoplast and is situated near the kinetosome. Pseudopodia: are temporary extensions of the cell membrane and found in amoebas. Its function is in locomotion & feeding. Filopodia: Rhizopodia:
  • Anatomy Of Protozoan Cell

    1. 1. Anatomy of Protozoan Cell Protozoa ? Unicellular organisms / single cell. Many species of Protozoa. Free Living & Parasitic.
    2. 2. Forms of Protozoa <ul><li>Large & heterogeneous group of organisms. </li></ul><ul><li>Various Body forms / plan. </li></ul><ul><li>Organelles of Protozoa conform to those of metazoan cells. </li></ul><ul><li>Ability to move </li></ul><ul><li>Mostly found in aquatic environment. </li></ul><ul><li>Can’t synthesize structural substances from inorganic matter. </li></ul><ul><li>200,000 Protozoan species (10,000 Parasitic in invertebrate & vertebrate hosts. </li></ul>
    3. 3. Prokaryotic Cells
    4. 4. Prokaryotic Cells (Prenucleus) <ul><li>Small unicellular organisms (0.2 – 2.0 µm in diameter and 2 – 8 µm in length. </li></ul><ul><li>Posseses indistinct nucleus (lack of nucleus & nucleoli). </li></ul><ul><li>Chromosome coiled like skein of wool. </li></ul><ul><li>Single circular chromosome with out histones. </li></ul><ul><li>Lack other membranous system (organelles) in cytoplasm. </li></ul><ul><li>Cell division by binary fission & fewer cell division structures than eukaryotes. </li></ul><ul><li>No meiosis. </li></ul>
    5. 5. Prokaryotic Cell
    6. 6. Eukaryotic Cell (Protozoa) <ul><li>Eukaryotic cells are large & structurally more complex. (10 – 100 µm in diameter). </li></ul><ul><li>Have membrane bound organelles. </li></ul><ul><li>Genetic material (DNA) is membrane bound i.e. enclosed in nucleus on chromosomes. </li></ul><ul><li>Nucleoli present. </li></ul><ul><li>Cell wall absent when present it is simple. </li></ul><ul><li>Multiple linear chromosomes with histones. </li></ul><ul><li>Mitosis </li></ul><ul><li>(Sexual reproduction) Meiosis </li></ul>
    7. 7. Eukaryotic Cell (Typical)
    8. 8. Eukaryotic Cell (Typical)
    9. 9. Organelles in Protozoa (Nucleus) <ul><li>Organelles : Specialized structure for various functions. </li></ul><ul><li>Bounded by double membrane nuclear envelope. </li></ul><ul><li>Membrane is perforated & connected with ER </li></ul><ul><li>Contains nucleolus or nucleoli (rRNA synthesized) or endosome (Karyosome). </li></ul><ul><li>Endosome is devoid of DNA. </li></ul><ul><li>Nucleus have different shapes (spherical, oval, cylindrical, sausage shape etc. </li></ul>
    10. 10. Protozoa (Nucleus)
    11. 11. Nucleus (Types) <ul><li>Macronucleus in ciliates (Cytoplasmic functions). </li></ul><ul><li>Micronucleus in Ciliates (dormant but active at sexual reproduction). </li></ul><ul><li>Two similar nuclei (Giardia). </li></ul><ul><li>Trophonucleus in trypanosome (control general life of cell). </li></ul><ul><li>Kinetoplast (kinetonucleus) regulate locomotion. </li></ul>
    12. 12. Trypanosoma
    13. 13. Protozoa (Cytoplasm) <ul><li>Substance inside the plasma membrane & Outside the nucleus </li></ul><ul><li>Extranuclear portion of cell. </li></ul><ul><li>Ectoplasm (Homogenous). </li></ul><ul><li>Endoplasm(granular contains various vacuoles & organelles). </li></ul><ul><li>Contains cytoskeleton (microfilaments, intermediate filaments & cylinders (microtubules) & provide support / shape. </li></ul>
    14. 14. Plasma Membrane & Cell wall <ul><li>Trilaminar (three layered) </li></ul><ul><li>4 – 10 nm thick </li></ul><ul><li>Double layer of lipid and single layer of protein. </li></ul><ul><li>Semi-permeable </li></ul><ul><li>Cell recognition </li></ul><ul><li>Secretion & excretion process </li></ul><ul><li>Membrane bound structures for binding </li></ul><ul><li>Junctions help in binding with host cells. </li></ul>
    15. 15. Plasma Membrane
    16. 16. Cell Wall <ul><li>Some parasitic stages may have & is inside or outside the cell membrane. Its composition is varied but consist of primarily proteins & others like CHO, fatty acids, phospholipid etc </li></ul><ul><li>Variable structural composition. </li></ul><ul><li>Protection. </li></ul><ul><li>Cell reorganization & nuclear division. </li></ul><ul><li>Single layered (Entamoeba & Giardia). </li></ul><ul><li>Double layered (coccidia). </li></ul>
    17. 17. Cyst / oocyst wall
    18. 18. Functions through Cell Membrane <ul><li>Transport (Endocytic vessicles) </li></ul><ul><li>A. Pinocytosis </li></ul><ul><li>B. Phagocytosis </li></ul><ul><li>Non mediated (Conc. Gradient) </li></ul><ul><li>Mediated transport (Active Transport) </li></ul><ul><li>Specialized structures for ingestion e.g. Cytostome </li></ul><ul><li>Specialized structures for excretion e.g. Cytopyge </li></ul><ul><li>Many protozoa have inner membrane known as Pellicle. </li></ul><ul><li>Outer surface coat known as glycocalyx . </li></ul>
    19. 19. Transport of Molecules
    20. 20. Structures for Ingestion / Excretion
    21. 21. Organelles in Protozoa <ul><li>Endoplasmic Reticulum (ER): </li></ul><ul><li>Rough ER ((Ribosome bounded), Smooth ER. </li></ul><ul><li>Membranous sacs or cisterns. </li></ul><ul><li>Synthesize lipid & store lipids & proteins. </li></ul><ul><li>Transport molecules to other parts of cells. </li></ul>
    22. 22. Organelles in Protozoa (Golgi Complex) <ul><li>Situated near the nucleus </li></ul><ul><li>Consist of many sacs / cistern like structures. </li></ul><ul><li>Receives proteins from ER & sorts, pack & deliver by secretory vesicles internally or externally. </li></ul>
    23. 23. Organelles (Mitochondria) <ul><li>Spherical or rod shaped. </li></ul><ul><li>Consist of double membrane. </li></ul><ul><li>Power house of cell due to ATP production. </li></ul><ul><li>Have their own DNA </li></ul>
    24. 24. Organelles <ul><li>Lysosome; formed from Golgi complex, membrane bound spheres, contain enzymes. </li></ul><ul><li>Vacuoles: Derived from Golgi bodies, storage place for sugar, proteins etc. </li></ul><ul><li>Centriole: Near nucleus, important in cell division. </li></ul><ul><li>Kinetosome (Basal Body): Axoneme originate from kinetosome. </li></ul>
    25. 25. Locomotion <ul><li>Cilia </li></ul><ul><li>Flagella </li></ul><ul><li>Pseudopodia </li></ul><ul><li>Gliding </li></ul>
    26. 26. Locomotion
    27. 27. Reproduction in Protozoa <ul><li>Asexual Reproduction </li></ul><ul><li>A. Binary Fission e.g. Giardia duodenalis, B. coli . </li></ul><ul><li>Division is random in Amoeba, longitudinal in flagellates, & transverse in ciliates. </li></ul><ul><li>Sequence of division is Kinetosome, kinetoplast, nucleus & cytokinesis. </li></ul><ul><li>B. Multiple Fission (Merogony, shizogony); </li></ul><ul><li>Repeated division of nucleus & other organelles before cytokinesis e.g. Apicomplexa </li></ul><ul><li>Schizont, meronts & segmenters </li></ul>
    28. 28. Reproduction in Protozoa <ul><li>Budding – Plasmotomy </li></ul><ul><li>Internal budding or endopolygeny: multiple daughter cells are formed anywhere in cytoplasm. </li></ul><ul><li>Endodyogeny : only two daughter cells are formed. </li></ul>
    29. 29. Reproduction in Protozoa (Sexual Reproduction) <ul><li>Gamonts: cells producing gametes </li></ul><ul><li>Gametogony: process of gamete production. </li></ul><ul><li>Amphimictic Reproduction: union of gametes from two parents. </li></ul><ul><li>Automictic Reproduction: One parent produces both gametes. </li></ul>
    30. 30. Reproduction in Protozoa (Sexual Reproduction) <ul><li>Syngamy : Union of gametes when they are whole cells is called syngamy. This union can be similar gametes (Isogametes) or different (Anisogametes). </li></ul><ul><li>Conjugation : Union of nuclei. Found in ciliates only. Macronuclei in each disintegrate and micronuclei undergo meiotic divisions into four haploid pronuclei. Two disintegrate and one migratory pronuclei will go to other cell & fuse with stationary pronuclei to form haploid cells. </li></ul>
    31. 31. Reproduction in Protozoa (Conjugation)