protozoa
Protozoa: Introduction
Protozoans are part of the Kingdom Protista
Protista include:Plant-like organisms such as green algae which were precursors of the plants
Fungus-like organisms such as slime molds which are heterotrophs that absorb nutrients from dead or decaying organic matter;They lack chitin in their cell walls;Animal-like organisms i.e. the Protozoa;These were precursors of animals;Gk: “Proto” means first, while “zoon” means animal ;Protozoans are part of the Kingdom Protista Protista include:Plant-like organisms such as green algae which were precursors of the plants;Fungus-like organisms such as slime molds which are heterotrophs that absorb nutrients from dead or decaying organic matter;They lack chitin in their cell walls;Animal-like organisms i.e. the Protozoa;These were precursors of animals Gk: “Proto” means first, while “zoon” means animal
Evolution of Eukaryotes;The transition to eukaryotic cells occurred about 2 billion years ago;Eukaryotes diverged from prokaryotes.First cells were bacteria-like.Origin of complex eukaryote cells;Most likely symbiosis among prokaryotic cells.Eukaryotic Organelles and Prokaryotic Symbionts ;The symbiotic model (first proposed by American Biologist - Lynn Margulis in the 1967.
Suggests possible symbiosis of bacteria within early eukaryotic cells. The theory of endosymbiosis and origin of mitochondria and chloroplasts;mitochondria and chloroplasts are the result of years of evolution initiated by the endocytosis of bacteria and blue-green algae which, instead of becoming digested, became symbiotic- Modification of engulfed prokaryote into an organelle:Primary endosymbiosis. The mitochondria of modern eukaryotic cells evolved from aerobic bacteria (probably related to the rickettsias) living within their host cell. (Aerobic bacteria engulfed by anaerobic bacteria).Engulfed photosynthetic bacteria (cyanobacteria) evolved into chloroplasts.Descendants in green algae lineage gave rise to multicellular plants.
Protozoa: Classification Protozoa differ mainly by how they move;Plylum Sarcomastigophora (ameoboids/flagellates)a) Subphylum Mastigophora – flagella b) Subphylum Sarcodina - pseudopods
2) Phylum Ciliophora (Ciliates) 3) Phlyum Apicomplexa,Class Sporozoa-non-motile, parasitic, therefore it depends on host’s circulation -e.g.Plasmodium vivax.
General Characteristics ;Eukaryotic, small, usually unicellular;Symmetry - asymmetry, radial, bilateral, or spherical ;Nucleus distinct, membrane-bound organelles present;Have no tissues or organs;Locomotion - pseudopodia, cilia, flagella, or body movement Cysts - formed by many species to survive unfavorable conditions;Mode of living:Free living-Most species occur as free-living organisms in aquatic or terrestrial environments.commensal e.g Entamoeba gingivalis in the human mouth-feeding on bacteria, dead epithelial cells and food particles Mutualistic e.g Trichonympha in termites abdomen whey they help to digest wood.Parasitic-e.g. Plasmodium which causes malaria;Reproduction – asexual by budding or sexual(conjugation)Subphylum Mastigophora - flagellates ;Possess a long slender flagellum for locomotion, food capture and as sense receptor
Are found in fresh and salt water, soil, or parasitic;Protozoa: Nervous System;Very simple, no systems but they are sensitive to: Light, touch and chemicals;Protozoa: Reproduction ;Most protozoa are asexual and reproduce by fission, budding, and multiple fission.Other protozoans are sexual and exchange genetic material from one cell to another through conjugation;Conjugation is the physical contact between cells.
Harmful effects of protozoans
Amoebic dysentery - contaminated food or water; bloody diarrhea;Giardiasis - Giardia lamblia (flagellate); contaminated water; explosive diarrhea
Malaria - Plasmodium vivax (sporazoa); mosquito bite ; fever, headache, fatigue, vomiting, coma
African sleeping sickness - Trypanosoma gambiense (flagellate); vector is the tse-tse fly; fever, weakness and lethargy
Leishmania (flagellate)– flesh eating parasite.Trichomonas (flagellate)- common STD
Chagas disease or American trypanosomiasis, is a tropical parasitic disease caused by the flagellate protozoanTrypanosoma cruzi
Trichomonas vaginalis ;an anaerobic, parasitic flagellated protozoan
is the causative agent of trichomoniasis.The WHO estimates that 180 million infections are acquired annually worldwide
There are between 5 and 8 million new infections each year;There is an estimated rate of asymptomatic cases as high as 50%.
Chagas diseases ;Caused byT. cruzi ;Transmitted to humans and other mammals by an insect vector the blood-sucking"kissing bugs"
These bugs belong to subfamily Triatominae (family Reduviidae) Most common species belong to the Triatoma and Rhodnius genera
MALARIA
According to the World Health Organization’s World Malaria Report 2005:At the end of 2004, some 3.2 billion people lived in areas at risk of malaria transmission in 107 countries and territories. Between 350 and 500 million clinical episodes of malaria occur every year.
At least one million deaths occur every year due to malaria. About 60% of the cases of malaria worldwide and more than 80% of the malaria deaths worldwide occur in Africa south of the Sahara. VIII.Beneficial effects of protozoans;Helps recycle dead organic material.Mutual symbiotes, like trichonnymphia in termites stomach.Primary part of the food chain.
REFERENCES
Young, J. Z. 1981. The Life of the Vertebrates (3rd Ed). Oxford University Press, Oxford.
Colbert, H. E. 1963. Evolution of vertebrates. Wiley Eastern Ltd, New Delhi. ISBN 085226125X
Pough, F. H., Heiser, J. B. and McFarland, W. N. 1999. Vertebrate Life (4th Ed.). Prentice Hall of India, New Delhi.
Hickman Jr., P. C. et al. 2011. Integrated Principles of Zoology (15th Ed.). McGraw-Hill. New York.
Miller, S. A. and Harley, J. P. 2002. Zoology (5th Ed.). McGrawl Hill. New York.
Textbook
Protozoans are part of the Kingdom Protista
Protista include:Plant-like organisms such as green algae which were precursors of the plants
Fungus-like organisms such as slime molds which are heterotrophs that absorb nutrients from dead or decaying organic matter;They lack chitin in their cell walls;Animal-like organisms i.e. the Protozoa;These were precursors of animals;Gk: “Proto” means first, while “zoon” means animal ;Protozoans are part of the Kingdom Protista Protista include:Plant-like organisms such as green algae which were precursors of the plants;Fungus-like organisms such as slime molds which are heterotrophs that absorb nutrients from dead or decaying organic matter;They lack chitin in their cell walls;Animal-like organisms i.e. the Protozoa;These were precursors of animals Gk: “Proto” means first, while “zoon” means animal
Evolution of Eukaryotes;The transition to eukaryotic cells occurred about 2 billion years ago;Eukaryotes diverged from prokaryotes.First cells were bacteria-like.Origin of complex eukaryote cells;Most likely symbiosis among prokaryotic cells.Eukaryotic Organelles and Prokaryotic Symbionts ;The symbiotic model (first proposed by American Biologist - Lynn Margulis in the 1967.
Suggests possible symbiosis of bacteria within early eukaryotic cells. The theory of endosymbiosis and origin of mitochondria and chloroplasts;mitochondria and chloroplasts are the result of years of evolution initiated by the endocytosis of bacteria and blue-green algae which, instead of becoming digested, became symbiotic- Modification of engulfed prokaryote into an organelle:Primary endosymbiosis. The mitochondria of modern eukaryotic cells evolved from aerobic bacteria (probably related to the rickettsias) living within their host cell. (Aerobic bacteria engulfed by anaerobic bacteria).Engulfed photosynthetic bacteria (cyanobacteria) evolved into chloroplasts.Descendants in green algae lineage gave rise to multicellular plants.
Protozoa: Classification Protozoa differ mainly by how they move;Plylum Sarcomastigophora (ameoboids/flagellates)a) Subphylum Mastigophora – flagella b) Subphylum Sarcodina - pseudopods
2) Phylum Ciliophora (Ciliates) 3) Phlyum Apicomplexa,Class Sporozoa-non-motile, parasitic, therefore it depends on host’s circulation -e.g.Plasmodium vivax.
General Characteristics ;Eukaryotic, small, usually unicellular;Symmetry - asymmetry, radial, bilateral, or spherical ;Nucleus distinct, membrane-bound organelles present;Have no tissues or organs;Locomotion - pseudopodia, cilia, flagella, or body movement Cysts - formed by many species to survive unfavorable conditions;Mode of living:Free living-Most species occur as free-living organisms in aquatic or terrestrial environments.commensal e.g Entamoeba gingivalis in the human mouth-feeding on bacteria, dead epithelial cells and food particles Mutualistic e.g Trichonympha in termites abdomen whey they help to digest wood.Parasitic-e.g. Plasmodium which causes malaria;Reproduction – asexual by budding or sexual(conjugation)Subphylum Mastigophora - flagellates ;Possess a long slender flagellum for locomotion, food capture and as sense receptor
Are found in fresh and salt water, soil, or parasitic;Protozoa: Nervous System;Very simple, no systems but they are sensitive to: Light, touch and chemicals;Protozoa: Reproduction ;Most protozoa are asexual and reproduce by fission, budding, and multiple fission.Other protozoans are sexual and exchange genetic material from one cell to another through conjugation;Conjugation is the physical contact between cells.
Harmful effects of protozoans
Amoebic dysentery - contaminated food or water; bloody diarrhea;Giardiasis - Giardia lamblia (flagellate); contaminated water; explosive diarrhea
Malaria - Plasmodium vivax (sporazoa); mosquito bite ; fever, headache, fatigue, vomiting, coma
African sleeping sickness - Trypanosoma gambiense (flagellate); vector is the tse-tse fly; fever, weakness and lethargy
Leishmania (flagellate)– flesh eating parasite.Trichomonas (flagellate)- common STD
Chagas disease or American trypanosomiasis, is a tropical parasitic disease caused by the flagellate protozoanTrypanosoma cruzi
Trichomonas vaginalis ;an anaerobic, parasitic flagellated protozoan
is the causative agent of trichomoniasis.The WHO estimates that 180 million infections are acquired annually worldwide
There are between 5 and 8 million new infections each year;There is an estimated rate of asymptomatic cases as high as 50%.
Chagas diseases ;Caused byT. cruzi ;Transmitted to humans and other mammals by an insect vector the blood-sucking"kissing bugs"
These bugs belong to subfamily Triatominae (family Reduviidae) Most common species belong to the Triatoma and Rhodnius genera
MALARIA
According to the World Health Organization’s World Malaria Report 2005:At the end of 2004, some 3.2 billion people lived in areas at risk of malaria transmission in 107 countries and territories. Between 350 and 500 million clinical episodes of malaria occur every year.
At least one million deaths occur every year due to malaria. About 60% of the cases of malaria worldwide and more than 80% of the malaria deaths worldwide occur in Africa south of the Sahara. VIII.Beneficial effects of protozoans;Helps recycle dead organic material.Mutual symbiotes, like trichonnymphia in termites stomach.Primary part of the food chain.
REFERENCES
Young, J. Z. 1981. The Life of the Vertebrates (3rd Ed). Oxford University Press, Oxford.
Colbert, H. E. 1963. Evolution of vertebrates. Wiley Eastern Ltd, New Delhi. ISBN 085226125X
Pough, F. H., Heiser, J. B. and McFarland, W. N. 1999. Vertebrate Life (4th Ed.). Prentice Hall of India, New Delhi.
Hickman Jr., P. C. et al. 2011. Integrated Principles of Zoology (15th Ed.). McGraw-Hill. New York.
Miller, S. A. and Harley, J. P. 2002. Zoology (5th Ed.). McGrawl Hill. New York.
Textbook
- Harrison,F.W,Cortiss.J.O,(ed).1991.Microscopic Anatomy of Invertebrates.Vol.1 Protozoa NewYork
- Pitelka,D.R,1963.Eletron-Microscopic Structures of Protozoa.Pergamon Press,Oxford
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