BIOL165 Lecture Notes - African Trypanosomiasis, Amoebiasis, Amoeba Proteus

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Published on 21 Apr 2013
School
University of Waterloo
Department
Biology
Course
BIOL165
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of 5
Biol 165: Diversity of Life 2013-04-21 2:36 PM
Kingdom Protoctista
Introduction
Protists are a paraphyletic group (ie, even some algae are included
in the group).
DNA/RNA studies indicate that it is a complicated group comprised
of serial endosymbiotic events.
most methods of classifying them prove to be inconvenient and not
easily accommodating to their differences.
each phylocode solves some problems while creating others.
Protists can be found in each of the 6 Eukaryote Supergroups:
o SuperGroup Opisthokonta
o SuperGroup Chromalveolata
o Supergroup Planta
The 3 groups of “primitive” Protozoan (unicellular eukaryote)
groups:
o SuperGroup Amoebozoa (amoebae and slime molds)
o SuperGroup Excavata (basal flagellates)
o SuperGroup Rhizaria
SuperGroup Amoebozoa
Is a primitive kind of protist
They move using pseudopodia, and the mode of travel is called
amoeboid locomotion.
They obtain food by phagocytosis
Phylum Pelobonta
Genus Pelomyxa
giant, and free-living
multinucleate and herbivorous
most primitive protist known; it lacks most organelles
Other Species: Phylum Rhizopodia
Amoeba proteus
o large and carnivorous
o common in fresh water, and even cracks in pavement
Entamoeba histolytica
o causes Amoebic dysentery
Cell Division: 3 Kinds
Promitosis
o the nuclear membrane and nucleolus remains intact.
o Chromosomes are not clear.
Mesomitosis
o nuclear membrane is intact, but nucleolus disintegrates
o there are no centrioles, and spindle fibres terminate at
nuclear membrane
Metamitosis
o typical mitosis occurs including nuclear membrane loss
o spindle fibres converge and operate w/o centrioles
o chromosomes are recognizable.
Cellular “Slime Molds”
ie, Phylum Acrasea and Phylum Dictyotstelida
Cellular slime molds spend most of their life cycle as free living
individual haploid protists.
Only when food is scarce do they aggregate to form a sporangium
to release microcysts.
The new microcysts release amoeboid cells, which can fuse to for a
macrocyst.
The macrocyst will then divide by meiosis to produce two haploid,
free-living amoeboid daughter cells.
Cellular Slime Molds have a heteromorphic life cycle – different
appearances during life cycle.
Plasmodial Slime Molds (PSM)/Acellular Slime Molds
Phylum Myxostelida
Genus Stemonitis and Lycogala
PSM are enormous single cells with thousands of nuclei
They are formed by the fusion of numerous individual flagellated
cells.
They also form sporangia/fruiting bodies, and disperse spores.
SuperGroup Excavata – Basal Flagellates
considered to be the most primitive of protists
many are disease causing, or parasitic
ie, Chagas disease, African Sleeping Sickness, leishmaniasis, some
STDs.
Amoebaflagellates
o Phylum Amoebgoflagellata
o have both amoeboid and flagellate stages in life cycle
o amoeboid stage lives in soil, normally only stage that can
feed.
o flagellated stage lives in pools of water
o can revert back and forth between life forms as needed.
Diplomanads
o Phylum Diplomonadida
o small heterotrophic protists
o do not have mitochondria
o most have symbiotic relationship within intestines of animals.
o Some are parasitic or cause disease
Giardia causes “hiker’s diarrhea”.
Euglenids
o most do not have chloroplasts
o ***are discussed in Algae Section
Kinetiplastids
o Phylum Kinetiplastida
o includes 2 groups:
1) Free living freshwater protists
2) Parasitic Trypanosomes (often use insect vectors)
Trypanosoma – Sleeping Sickness
Leishmania
Parabasalians
o Phylum Parabasalia

Document Summary

Supergroup amoebozoa: is a primitive kind of protist, they move using pseudopodia, and the mode of travel is called amoeboid locomotion, they obtain food by phagocytosis. Genus pelomyxa: giant, and free-living, multinucleate and herbivorous, most primitive protist known; it lacks most organelles. Other species: phylum rhizopodia: amoeba proteus large and carnivorous, common in fresh water, and even cracks in pavement, entamoeba histolytica, causes amoebic dysentery. Supergroup excavata basal flagellates: considered to be the most primitive of protists, many are disease causing, or parasitic ie, chagas disease, african sleeping sickness, leishmaniasis, some. Giardia causes hiker"s diarrhea : euglenids, most do not have chloroplasts, ***are discussed in algae section, kinetiplastids, phylum kinetiplastida includes 2 groups: 2) parasitic trypanosomes (often use insect vectors) Leishmania: parabasalians, phylum parabasalia, often associated with animals, some have symbiotic relationship with bacteria in gut of invertebrates. Life cycle of kinetiplastida: trypanosoma causes african sleeping sickness, vector is tsetse fly.