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Overview of protozoa
Overview of protozoa
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Protozoa

  1. 1. PROTOZOA PROTOS-FIRST ZOON-ANIMAL Eucaryotic, unicellular microorganism
  2. 2. Occurrence • Almost all habitat • Sea, soil, fresh water, polar regions and very high altitude
  3. 3. Ecology • Free living • Symbiotic – parasitic- mutualistic Free living- Factors affecting the distribution and the no.- 1. light- photosynthetic protozoa have chromatophore. Some are present in absence of light. 2. pH- 3.2-8.7 (6-8 is optimal for metabolism)
  4. 4. Factors affecting the distribution and the number of protozoa 3.a. Nutrients-water rich in oxygen and low in organic matter (mountain springs, ponds) b. some require water rich in minerals c. some grow well in water where there is active oxidation and degradation of organic matter (eg. Ciliates) d. Salt water e. fresh water f. in less oxygen g. presence of bacteria, protozoa for holozoic protozoa The nutrient supply is a major determining factor in the distribution and number of protozoa
  5. 5. Factors affecting the distribution and the number of protozoa 4. Temperature – 16-250 c (optimum), 36-400c (maximum) The encysted stage will thrive high temperature. So their no will be more in warm environment
  6. 6. Symbiotic protozoa • Commensalism-the host is neither harmed nor benefitted- 1.Ectocommensalism- protozoa attaches themselves to a host’s body 2.Endocommensalism- when protozoan is inside the host eg. The protozoa inside the gut of the host • Mutualism- both the parasite and the host are benefitted. Eg, the flagellates in the gut of termite digest woody materials consumed by termites. These are converted into glycogenous substances used by the host. In absence of each other both perish
  7. 7. Symbiotic protozoa • Parasitism- the parasite lives at the expense of other. The parasite feeds on others with the help of pseudopodia or cytosome. • Hyperparasitism- parasitic protozoa parasitizes
  8. 8. Morphology Size an shape- variable, 2mm to 15 cm Intracellular structure-
  9. 9. Cytoplasm • Homogeneous, show colours (green, brown, blue , purple due to pigment • Has submicroscopic protein fibrils (myonemes, microtubules) • Arranged in parallel • Divided in two portions- ectoplasm & endoplasm • Ectoplasm- more gel like and endoplasm is voluminous and fluid • Cell organelles are present (ER, ribosomes, golgi complex, mitochondria, food vacuole, contractile vacuole, kinetosome)
  10. 10. plasmalemma
  11. 11. Nucleus • Eucaryotic nucleus- has chromosomes, the nucleolar substance, the nuclear membrane, nucleoplasm • one or many • Some have two- a. Macronucleus- large in size, controls the metabolic the metabolic activities and regeneration processes b. Micronucleus- small in size concerned with reproductive activity
  12. 12. Plasmalemma & other coverings Cell membrane or plasmalemma- outermost layer, semi permeable Functions- a. protection b. site of perception of chemical and mechanical stimuli c. transport
  13. 13. Compound coverings • Combinations of membranes, also called pellicle • Simplest is plasmalemma eg, Amoeba • Some have mucopolysaccharide on plasmalemma plays an important role in pinocytosis and adhesion • Can be thick, ridged and sculputured, nodular thickening,
  14. 14. Additional coverings • Diverse • Egs. thecae, shells, tests or loricae • Thecae- directly secreted by the organism • Others are the loose coverings • Made up of organic and inorganic materials (calcium carbonate and silica)
  15. 15. thecae
  16. 16. Feeding structures • Pseudopodia- in Amoeba • Tentacular feeding tubes- in suctorians • Mouth (cytosome)- in ciliates a. simple round opening b. a slit like- remains open all the time in some and some have slit which can be opened and closed and always located anteriorly • Oral groove- an indentation in the pellicle , guides food toward the cytosome and act as a concentrating device • Peristome- this an oral groove with membanelles • Cytopharynx- it is a region through which the food must pass and is enclosed in the food vacuole.
  17. 17. Feeding structures pseudopodia Tentacular feeding tubes
  18. 18. cysts • Resistant structure • Able to survive an adverse conditions like dessication, low nutrient supply, lack of oxygen etc. • Cyst stage is an infective stage for intestinal pathogens • Cyst is important mean of asexual reproduction
  19. 19. Other protective structures • Mucocyst- membrane bound vesicle secrete mucilage • Trichocyst- harpoon like weapon used by some protozoa to defend • Toxicyst- tubular thread like structure, secrets toxin to paralyze and capture prey • Haptocyst- used to contact and immobilize prey. They are present in the tentacles of suctorian.
  20. 20. Locomotor organelles Pseudopodia- it is a temporary projection of part of the cytoplasm of some protozoa not having rigid pellicle • It is the characteristic of amoebas • Used for capturing and engulfment of food Flagella - • fine filamentous extension of the cell, 9+2 arrangement • 1-8 per cell
  21. 21. Locomotor organelles cilia- • thinner and shorter than flagella • Apart from locomotion helps in ingestion of food • Tactile organelle • Arranged in longitudinal, oblique, or spiral rows Undulating membrane-
  22. 22. Reproduction (Asexual reproduction) Asexual reproduction- Binary fission- two daughter cells are formed
  23. 23. Reproduction (Asexual reproduction) Multiple fission- many daughter cells are formed
  24. 24. Reproduction (Asexual reproduction) Budding- Exogenous- Endogenous-
  25. 25. Sexual reproduction- • Syngamy or gametogamy
  26. 26. Life cycle of amoeba
  27. 27. Importance of Protozoa • Important link in the food chain in aquatic environment eg. Marine water I. LIGHT PHYTOPLANKTON ZOOPLANKTON (primary producer) (pri. consumer) CARNIVORES sec. consumer
  28. 28. Dead bodies of producers and consumers and their excreta including faeces Decomposed by fungi and bacteria Ingestion of bacteria by protozoa
  29. 29. Importance of Protozoa 1. Sewage treatment (biological)-aerobic and anaerobic protozoa 2. Industrial waste treatment- rich in nitrates and phosphates. In the settling tank illumination is done to increase the growth of algae and protozoa.

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