08. protista short - 1 How and why did the first eukaryotic...

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1 1 How and why did the first eukaryotic cells come about? • Flexible exterior – loss of cell wall • Cytoskeleton • Internal vesicles, vacuoles, endoplasmic reticulum • Nuclear envelope – true nucleus • mitochondria, chloroplasts through endosymbiosis • Larger size: up to 100 X larger than bacteria 2 What advantage does the cytoskeleton provide? • Shape changes • Food ingestion • Internal movement of vesicles • Mitosis/ meiosis • ‘muscular’ activities 3 A flexible exterior plus a cytoskeleton allowed the formation of pockets that could become food vesicles 4 A membrane-bound part of the cytoskeleton became a more complex flagellum, and some of the membranes became the nuclear membrane 5 How do flagella of eukaryotes differ from those of the prokaryotes? 9+2 structure 6 What is the evidence for endosymbiosis of mitochondria and chloroplasts?
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2 7 The early predatory cells may have “ingested but not digested” an aerobic bacterium that became the first mitochondrion; later, cyanobacteria were ingested that became the first chloroplasts 8 Animal-like protists feed by ingestion and can actively detect and pursue their prey 9 Amoeboid cells can be found in many eukaryote clades, including mammals! Amoeboid cell from human immune system 10 What is a protist? • A member of a paraphyletic kingdom (Protista) created to contain the simpler animal-like, plant-like and fungus-like eukaryotes • Protists are mostly unicellular, filamentous or colonial, but some (“seaweeds”) have complex multicellular bodies 11 The eukaryotes split into up to 10 major clades early on, all of which contain “protist” members An alternate view, with 7 major clades 12
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3 13 What are the three nutritional modes of protists? • Animal-like (“protozoa”) – heterotrophs that
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This note was uploaded on 02/10/2010 for the course BSC 2010 taught by Professor Essig during the Spring '10 term at University of Southern Maine.

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08. protista short - 1 How and why did the first eukaryotic...

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