Protozoa

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اشترك في: الخميس إبريل 04, 2013 10:28 pm

Protozoa

مشاركةبواسطة دكتور كمال سيد » الأربعاء إبريل 24, 2013 5:40 pm


introduction

Protozoa are a diverse group of unicellular eukaryotic organisms, many of which are motile. Originally, protozoa had been defined as unicellular protists with animal-like behavior, e.g., movement. Protozoa were regarded as the partner group of protists to protophyta, which have plant-like behaviour, e.g., photosynthesis

Classification

Protozoa were previously often grouped in the kingdom of Protista, together with the plant-like algae and fungus-like slime molds. As a result of 21st-century systematics, protozoa, along with ciliates, mastigophorans, and apicomplexans, are arranged as animal-like protists. With the possible exception of Myxozoa, protozoa are not categorized as Metazoa.[6] Protozoa are unicellular organisms and are often called the animal-like protists because they subsist entirely on other organisms for food. Most protozoa can move about on their own. Amoebas, paramecia, and trypanosomes are all examples of animal-like protists.
[edit]Sub-groups
The classification of protozoa has been and remains a problematic area of taxonomy. Where they are available, DNA sequences are used as the basis for classification but for the majority of described protozoa such material is not available. They have been and still are mostly on the basis of their morphology and for the parasitic species their hosts. Protozoa have been divided traditionally[citation needed] on the basis of their means of locomotion.
Flagellates (e.g., Giardia lamblia)
Amoeboids (e.g., Entamoeba histolytica)
Sporozoans (e.g., Plasmodium knowlesi)
Apicomplexa
Myxozoa
Microsporidia
Ciliates (e.g., Balantidium coli)

Human disease

Some protozoa are human parasites, causing diseases. Examples of human diseases caused by protozoa:
Malaria
Amoebiasis
Giardiasis
Toxoplasmosis
Cryptosporidiosis
Trichomoniasis
Chagas disease
Leishmaniasis
Sleeping Sickness
Dysentery
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