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By Henry Hsieh Perry Huang Kevin Kim Joon Park Period 6. Chapter 28 The Origins of Eukaryotic Diversity. Introduction to the Protists. Protists existed at least a billion years ago, before the origin of plants, fungi, and animals They were the earliest descendants of prokaryotes
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Chapter 28The Origins of Eukaryotic Diversity
-Molecular indicates that two groups of flagllates
euglenoids and kinetoplastids make up the monophyletic candidate kingdom Euglenozoa.
Euglenoids-(Englena and its close relatives)are characterized by an anterior pocket, or chamber, from which one or two flagella emerge.
Paramylum, a glucose ploymer that functions as a storage molecule, is also characteristic of euglenoids.
Euglena is chiefy autotrophic, absorbing organic molecules from their surroundings or engulfing prey by phagocytosis.
The kinetoplastids have a single large mitochondrion associated with unique organelle, the kinetoplast, that houses extranulear DNA.Candidate kingdom Euglenozoa includes both autotrophic and heterotrophic flagellates
Subsurface cavities(alveoli) are diagnostic of candidate kingdom Alveolata
Another monophyletic candidate kingdom that is emerging from molecular systematics,
-draws together a group of photosynthetic flagellates ( the dinoflagellates),
-a group of parasites (apicomplexans),
-and a a distinctive group of eukaryotes that move by means of cilia( the cilates).
-Alveolates have a small membrane-bounded cavities (alveoli) under their cell surfaces,
functions are unknown; may help stabilize the cell surface and regulate the cell’s water and ion content
Dinoflagellates are abundant components of the vast aquatic pastures of phytoplankton that are suspended near the water surface and provide the foundation of most marine and many freshwater food webs. There are also heterotrophic species of dinoflagellates.
Apicomplexans are parasites of animals,
Some cause serious human diseases
The parasites disseminate as tiny infectious cells called sporozoiteDinoflagellata (Dinoflagellates)& Apicomplexa (Apicomplexans)
Fig 28-13. The two-host life history of Plasmodium , the apicomplexan that causes malaria. (Colors are not true to life.)
Fig 28-15. Conjugation and genetic recombination in Paramecium caudatum .
(These organisms spread via contaminated drinking water, food, or eating utensils)
(Many also derive nourishment from the photosynthesis of symbiotic algae that live w/in the shells)