Ch.25 Protists p.530-533
Evolution of the eukaryotes
protists were the first eukaryotic cells to evolve from ancestral prokaryotes.
monophyletic
evolved from a common ancestor electron microscopy reveals similar structural patterns among these protist taxa that comparative molecular evidence suggests are monophyletic
ultra structure
the fine details of cell structure revealed by electron microscopy
most biologists regard the protist kingdom as a paraphyletic group
the protist kingdom contains some but not all, of the descendants of a common eukaryotic ancestor.
Protists
unicellular, colonial, or simple multicellular organisms that have a eukaryotic cell organization.
parasitism
where one partner (the parasite) lives on or in another (the host) and metabolicaly depends on them
commensalism
where one partner benefits and the other is unaffected
most protists are unicellular
with each cell forming a complete organism capable of preforming all the functions characteristic of life.
Describe the kinds of data biologists use to classify eukaryotes.
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Discuss the hypothesis of serial endosymbiosis, and briefly describe some of the evidence that supports it.
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Introduction to the protists
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a consensus is emerging in eukaryote classification
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Key Concepts
Protists are a divers group of eukaryotic organisms, most of them are microscopic. Protists carry in body plan (unicellular, colonial, coenocytic, multicellular), method of motility (pseudopodia, cilia, flagella), nutrition type (autotrophic, heterotrophic) and mode of reproduction (asexual, sexual). Protists are descendants of early eukaryotes. Animals, fungi, and plants evolved from protist ancestors. Biologists are making a progress in understanding the evolutionary relationships among various protist taxa.
Characterize the features common to the members of kingdom Protista
Protists are mostly unicellular eukaryotic organisms that live in aquatic environments. Protists range in size from microscopic unicellular organisms to colonies ( loosely connected groups of cells) to coencytes (multinucleate masses of cytoplasm) to multicellular organisms (composed of many cells).
mutualism
a more or less equal partnership where both partners benefit
coenocytic
colonies that consist of multinucleate mass of cytoplasm.
some protists are multicellular
composed of many cells, but with simple body forms without specialized tissues
planktons
floating, often microscopic organisms that inhabit surface waters and are the base of the food web in aquatic ecosystems.
some protists form colonies
loosely connected groups of cells
Discuss in general terms the diversity inherent in the protist kingdom, including means of locomotion, modes of nutrition, interactions with other organisms, habitats, and modes of reproduction.
protist have various means of locomotion, including pseudopodia, flagella, and cilia. a few are nonmotile. protist obtain their nutrients autotrophically or heterotrophically. protists are free-living or symbiotic, with symbiotic relationships ranging from mutualism to parasitism. Most protists live in the ocean or in freshwater ponds, lakes and streams. Parasitic protists live in the body fluids of their hosts. Many protists reproduce both sexually or asexually; others reproduce only asexually.
protist work with other organisms
protists that form stable symbiotic associations with unrelated organisms.