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Zoology Chapter 11 Protozoa

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1. unicellular with some colonial and multicellular stages. 2. most are microscopic. 3. all symmetries are present. 4. no germ layers are present. – PowerPoint PPT presentation

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Title: Zoology Chapter 11 Protozoa


1
Zoology Chapter 11Protozoa
2
Characteristics of Protozoans
  • 1. unicellular with some colonial and
    multicellular stages.
  • 2. most are microscopic.
  • 3. all symmetries are present.
  • 4. no germ layers are present.
  • 5. they include free-living, mutualistic,
    commensal and parasitic forms.

3
  • 6. they move by pseudopodia, flagella, cilia and
    they can direct cell movements.
  • 7. all types of nutrition are present
    autotrophic, heterotrophic and saprozoic.
  • 8. they are ecologically diverse, widely
    dispersed, but many are limited to narrow
    environmental ranges.
  • 9. reproduction is asexual by fission, budding
    or cysts sexual by conjugation of syngamy of
    gametes.

4
Form and Function
  • A. Nucleus and cytoplasm
  • The nucleus is membrane bound and contains DNA in
    the form of chromosomes.
  • Nucleoli are often present inside the nucleus.
  • Cytoplasm may be divided into a granular
    endoplasm and a transparent gel ectoplasm.

5
  • B. Locomotor organelles cilia and flagella
  • C. Pseudopodia chief means of locomotion in
    Sarcodina, many flagellates and ameboid cells of
    many invertebrates and vertebrates.
  • Lobopodia are large blunt extensions containing
    both endoplasm and ectoplasm
  • In the limax form, the whole body moves rather
    than sending out arms.
  • Filopodia are thin extensions of ectoplasm
  • Reticulopodia repeatedly rejoin to form a
    netlike mesh.

6
  • D. Excretion and Osmoregulation
  • 1. excretion of metabolic wastes is by
    diffusion, although many ciliates have a point of
    expulsion of wastes, called a cytoproct.
  • 2. contractile vacuoles fill and empty to
    maintain osmotic balance.

7
  • E. Nutrition
  • 1. Autotrophs synthesize their own food and
    heterotrophs obtain organic molecules made by
    others.
  • 2. Phagotrophs or holozoic feeders ingest food
    particles while osmotrophs or saprozoic feeders
    ingest soluble food.
  • 3. Most protozoans use more than one nutritional
    strategy.

8
  • F. Reproduction
  • 1. Asexual reproduction
  • Fission
  • Budding
  • Multiple fission (schizogony)

9
  • 2. Sexual reproduction
  • Fertilization of one gamete by another is
    syngamy this is the stantard form of sexual
    reproduction.
  • Isogametes look alike anisogametes (like egg
    and sperm) are dissimilar.
  • Autogamy is when gametic nuclei arise by meiosis
    and fuse to form a zygote inside the parent
    organism.
  • Conjugation is exchange of gametic nuclei between
    paired organisms, common in Paramecium.

10
  • G. Encystment and Excystment
  • 1. protected only by a delicate membrane,
    protozoa are successful in changing and harsh
    environments.
  • 2. Cysts are dormant forms that shut down
    metabolism and have a resistant material
    covering.
  • 3. cysts often resist cold or hot temperatures
    some tolerate acidity but not sunlight.
  • 4. once under favorable conditions again, the
    organism escapes from the cyst.

11
Representative Types
  • Trichomonas vaginalis infects the urogenital
    tract of humans and is sexually transmitted.

12
  • Euglena

13
  • Volvox

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  • Trypanosoma brucei gambiense

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  • Trypanosoma cruzi

16
  • Leishmania

17
  • Amoeba proteus

18
  • Entamoeba histolytica

19
  • Toxoplasma gondii

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  • Plasmodium

21
  • Paramecium
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