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PROTOZOA _slide_presentation slide .ppt
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- 2. • Some protistsare plantlike because they are primarily autotrophic • Others are animal-like because they are primarily heterotrophic
- 3. • Protozoa traditionallyreferred to chemoorganotrophic protists. • organisms that use organic compounds as a source of energy, electrons, and carbon for biosynthesis i.e. Heterotrophic
- 4. • A protozoanis a complete organism in which all life activities are carried out within a single plasma membrane. • Protozoans lack collagen and chitinous cell walls. • Protozoa show unicellular eukaryote organization FEATURES OF PROTOZOA
- 5. • Often, theyare more complex than any particular cell in higher organisms. • Some protozoans form colonies yet independent on one another for most functions. • Some colonies can become complex
- 6. • A regulararrangement of microtubules, called the pellicle, underlies the plasma membrane of many protozoa. • The pellicle is rigid enough to maintain the shape of the protozoan, but it is also flexible
- 7. • The cytoplasmof a protozoan is differentiated into two regions. • ectoplasm • endoplasm
- 8. • Water entersfreshwater protozoa with higher solute concentrations by osmosis. • Contractile vacuoles remove this excess water • Most protozoa absorb dissolved nutrients either by active transport or by ingesting whole or particulate food through endocytosis.
- 9. • Some protozoaingest food through a specialized region cytostome cytostome and cytopharynx cytopharynx, analogous to a mouth. • Digestion and transport of food occurs in food vacuoles food vacuoles that form during endocytosis. • Food vacuoles fuse with enzyme containing lysosomes lysosomes and circulate through the cytoplasm, distributing the products of digestion.
- 10. • After digestionis complete, the egestion vacuoles release their waste contents by exocytosis exocytosis at a specialized region of the plasma membrane or pellicle called the cytopyge cytopyge.
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- 12. REPRODUCTION • Protozoa reproduceboth sexually and asexually • One of the simplest and most common forms of asexual reproduction is binary fission. • Binary fission can be longitudinal (e.g., euglenoids) or transverse (e.g., ciliates).
- 13. Longitudinal binary fissionin the Euglena begins with mitosis and then cytoplasmic division (cytokinesis) divides the organelles between the two cells and results in two similarly sized protozoa.
- 14. Transverse binary fissionin the cilates
- 15. • Budding isanother form of asexual reproduction in which mitosis is followed by the incorporation of one nucleus into a cytoplasmic mass that is much smaller than the parent cell. • Schizogony or multiple fission results in a large number of daughter cells from the division of a single parent.
- 16. • Sexual reproduction Sexualreproduction involves gamete formation and the subsequent fusion of gametes to form a zygote. • In most protozoa, the sexually mature individual is haploid. • Gametes are produced by mitosis, and meiosis follows the union of the gametes.
- 17. CLASSIFICATION • Protists constitutesuch an unnatural group • Some protist are more closely related to plants fungi or animals than they are to other protist
- 18. • 7 Phylaof the protozoan are recognized using the older classification: Sarcomastigophora • Labyrinthomorpha • Apicomplexa • Microspora • Acetospora • Myxozoa • Ciliophora
- 19. • Recent classificationusing metagenomic studies grouped the protozoans according to their phylogenetic relatedness. • Microsporidians once considered amitochondriate protists are now classified as fungi
- 20. Phylum Sarcomastigophora • Possessonly one type of nucleus and flagella or pseudopodia or both as locomotor or feeding organelles • Contains 3 sub-phyla Mastigophora, Sarcodina & Opalinata
- 21. • Subphylum Mastigophoransare flagellates that move by means of one flagellum or more flagella • Phytoflagellates are mostly biflagellated chlorophyll-bearing autotrophs or mixotrophs eg Euglenids
- 22. • Zooflagellates bearone to many flagella and are heterotrophic • Asexual reproduction is by longitudinal fission • Although there are some free-living species, most are commensal or parasitic
- 23. • Recent groupingplaced Giardia intestinalis under Diplomonads based on modified mitochondria called mitosomes • Mitosomes lack functional electron transport chains and hence get the energy they need from anaerobic pathway
- 24. • Trichomonas vaginaliswhich cause the STD trichomoniasis is grouped as parabasalia have reduced mitochondria called hydrogenosome. • Hydrogenosome can generate energy anaerobically releasing hydrogen gas
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- 27. Locomotory flagellum Red eyespot/Stigma Rudimentary/2nd flagellum Reservoir Nucleus Contractilevacuole Paramylon Pellicle Chloroplasts Mitochondria Golgi Complex Basal Body Euglena viridis
- 28. • The Diplomonads,Parabasalids and Euglenozoans are grouped under a supergroup EXCAVATA because of the presence of excavated groove on one side of the cell body • Excavata has a posteriorly directed flagellum which generate feeding current
- 29. Sub-phylum Opalinata • Membersoccur in the rectum of frogs & toads • All are parasitic with monomorphic nuclei (not differentiated macronuclei & micronuclei)
- 30. Numerous cilia-like organelle(obliquely arranged) cover entire body surface & are of equal size Some have many nuclei, others have only two There is no cytostome
- 31. Opalina ranarum * Bodyis oval and flat * Multinucleated Nuclei Lines of cilia Cilia Pellicle Ecto-plasm Endo-plasm
- 32. Sub-phylum Sarcodina • Theypossess pseudopodia (flowing extensions of the body) • Possess fewer organelles than ciliates and flagellates • Distinguished by the form of pseudopodia and cytoskeleton.
- 33. • Lobopodia Lobopodia arebroad cell processes containing ectoplasm and endoplasm • Filopodia Filopodia are thread-like and contain ectoplasm only • Reticulopodia Reticulopodia are net-like series of cell extensions
- 34. • Axopodia Axopodia arethin filamentous cell extension supported by a central axis of microtubules
- 35. • Amoebozoa engulffood by phagocytosis • Free-living Amoebas feed on bacteria, diatoms, algae, rotifers • Entamoeba coli is a commensal species that feed on bacteria and intestinal debris • The parasitic E. histolitica is causative agent of amoebic dysentery • Both leave as cyst in feces and reinfect via the mouth
- 36. • Binary fissionoccurs when an aboeba reaches a certain size limit • No sexual reproduction is known to occur
- 37. • Some membersof the sarcodines lack a test (shell) or other supporting structures • Others possess test which may be calcareous proteineous, siliceous or chitinous. • Other test may compose of sand and debris cemented into a secreted matrix
- 38. • Supper ClassRhizopoda • Pseudopodia used for locomotion and feeding • Some spp have shell composed of mineral particles cemented together • Large opening in the shell permit extension of the body and pseudopodia
- 39. • Class Lobosea •Shelled or naked amoebae. • Pseudopodia is large and blunt (Lobopods) • Amoeba proteus, Diffugia
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- 42. Amoeba proteus (TypeRepresentative ) Classification Kingdom Protista (sub-kingdom Protozoa) Phylum Sarcomastigophora Subphylum Sarcodina Super class Rhizopodia Class Lobosea Order Amoebida Genus Amoeba Species proteus
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- 44. • Class Granuloreticulosea (Foraminiferans) •Mostly marine • Rhizopods with one chamber or multichambered calcareous shell • They have strand-like branching pseudopodia
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- 46. Supper Class Actinopoda •Floating or sessile sarcodines with radiating rodlike pseudopodia (axopods) used in feeding only • Composed of medulla that contains one to many nuclei and an outer cortex of highly vacuolated cytoplasm
- 47. • Class Polycystinea(Radiolarian) • Medulla encased within a membranous capsule perforated to permit communication with the outer cortex • Siliceous skeleton
- 48. • Class Acantherea •Radiolarians with skeleton of stontium
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- 50. • Class Heliozoea •Heliozoans are mostly marine and freshwater sarcodines lacking a central capsule • Skeleton of siliceous scales, tubes spheres or needles embedded in the cortex
- 51. • The recentclassification grouped amoeboid protozoans that possess filopodia into monophyletic clade called Rhizaria (Forams, Radiolarians, Heliozoans) • The amoebas with lobopodia form another clade called Amoebozoa • Amoebozoa include Tubulinea, Acanthamoebida and Entamoeba
- 52. LIFE HISTORY Growth& multiplication is by fission : Involving nuclear division by mitosis followed by cytoplasmic division Two amoebae separate to feed & grow to maximum sizes.
- 53. Under unfavourable conditions Amoebaforms cyst & remain inactive , until moisture or warm temperature are restored They then emerge, begin to feed and grow.
- 54. Asexual binaryfission is triggered off when the surface area : volume ratio and / or cytoplasmic volume : nuclear volume ratio reach a limit. There may be sporulation in other species like Entamoeba histolytica which undergo spore formation
- 55. References • Intergrated Principlesof Zoology.---- Hickman, Roberts & Larson • Zoology.---- Miller& Harley • Invertebrate Zoology.--- Jordan &Verma • Campbell Biology.--- Reece et al