“Animal-Like” Protists: Protozoans. “Animal-like” Protists: Protozoans Kingdom Protista Four...
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Transcript of “Animal-Like” Protists: Protozoans. “Animal-like” Protists: Protozoans Kingdom Protista Four...
“Animal-Like” Protists:
Protozoans
“Animal-like” Protists: Protozoans
• Kingdom Protista• Four phyla of “animal-like” protists
differentiated by locomotion• All heterotrophs• Protists that live primarily by ingesting food are
called protozoans.
Phylum Zoomastigina - Flagellates
• Move by flagella – long, whip-like structures
• Absorb food through cell membranes
• No shell• Some free-living, some parasites• Most reproduce asexually by
binary fission = genetically identical. Some reproduce sexually as well – gametes formed by meiosis = new combination of genetic information.
Phylum Sarcodina - Sarcodines• Best known sarcodina is
amoeba • Move and feed by use of
pseudopods – temporary projections of cytoplasm
• No body shape, the “blob”• Move by amoeboid movement
– cytoplasm of the cell streams into the pseudopod, and the rest of the cell follows
• Food vacuole temporarily stores food
• Reproduce by binary fission
Amoeboid Movement
Amoeba Anatomy
Food vacuole
Nucleus
Contractile vacuole
Pseudopods
Other Sarcodinas• Heliozoans and radiolarians – these both produce shells of SiO2
(silica)
• Foraminifers – produce shells of CaCO3 (calcium carbonate), used in dating rocks and chalk
Phylum Sporozoa - Sporozoans• Do not move, all are
parasitic• Live in worms, insects, fish,
birds, and humans• Very complex life cycles• Reproduce by means of
spores (groups of cells which invade a new host)
• Also known as Apicomplexans
Plasmodium killing red blood cells
The Life Cycle of PlasmodiumPlasmodium undergoes several stages of development in mosquito’s body
Mosquito bites human, injecting saliva that contains Plasmodium sporozoites
Plasmodium sporozoites
Sporozoites infect liver cells
Liver
Infected liver cells burst, releasing Plasmodium cells that infect red blood cells
Plasmodium cells
Red blood cells
Infected red blood cells burst, releasing Plasmodium cells; some can infect other red blood cells, and others can infect mosquitoes
Anopheles mosquito bites infected human and picks up Plasmodium cells
Phylum Ciliophora – Ciliates
• Cilia – short, hair-like projections used in feeding and/or locomotion
• Found in fresh and saltwater
• Most are free-living• Genus Paramecium
one of the most studied protists
Anatomy of Typical ciliate• Pellicle – “skin”• Trichocysts – small, bottle-shaped structures used for
defense and protection• Macronucleus – daily genetic material• Micronucleus – contains “reserve copy” of cell’s
genes/reproduction genetic material• Gullet – indentation in one side of organism to trap food• Food vacuole – food storage and digestion• Anal pore – excretion• Contractile vacuoles – collect water and when full,
contracts, pumping water out– Why is this necessary?
Paramecium Anatomy
Anal pore
GulletOral groove
TrichocystsLysosomes
Food vacuoles
Contractile vacuole
Micronucleus
MacronucleusCilia
Reproduction of Ciliates• Under most conditions, ciliates reproduce
asexually by mitosis and binary fission – cell splits lengthwise, forming 2 genetically identical cells
• When placed under stress, conjugation may occur
• Conjugation allows for a crossover of genetic information, but in the end, the two cells are genetically the same – the two cells simply swapped half of each other’s genetic information. This does make new combinations of genes though = genetic diversity
Conjugation
Macronucleus
Micronucleus
Conjugation
Macronucleus
Micronucleus
Conjugation
Macronucleus
Micronucleus
Conjugation
Macronucleus
Micronucleus
“Animal-like” Protists and Disease
• Sporozoans – Plasmodium – malaria, Toxoplasma – damages nervous system
• Zoomastigina – Trypanosoma – African sleeping sickness
• Sarcodina – Entamoeba – amebic dysentery
Ecology of “Animal-like” Protists – Helpful
• Serve as food at the base of the food chain
• Trichonympha – live inside termites and help break down cellulose in wood for termites to then digest