Lecture_8_Protists_and_Fungi

Lecture_8_Protists_and_Fungi - 6/15/2011 Whats a eukaryote?...

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6/15/2011 1 Protists and Fungi LS1: Summer Session A July 11, 2011 What’s a eukaryote? True nucleus Multiple, linear chromosomes Cytoplasmic organelles Mitochondria ER Golgi complex Chloroplasts Microtubules/microfilaments (cytoskeleton) Asexual or sexual reproduction Common origin of eukaryotes Similar features in eukaryotes (as well as recent genetically- based phylogenies) suggest a common origin The bulk of eukaryote lineages are organisms that are classified as protists The origin of eukaryotes The modern eukaryotic cell required a unique set of adaptations that allowed it to form: A flexible cell membrane A cytoskeleton A nuclear envelope Digestive vacuoles Endosymbionts Endosymbiosis Mitochondria and chloroplasts, having their own DNA and multiple membranes, are believed to have originated through the process of endosymbiosis Primary endosymbiosis Secondary endosymbiosis Tertiary endosymbiosis
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6/15/2011 2 Eukaryotic diversity Eukaryotes diversified into many discrete lineages The bulk of eukaryote lineages are organisms that are classified as protists What is a protist? A better question is… What is it NOT? Protists are a hugely diverse paraphyletic group, encompassing all eukaryotes except the plants, animals, and fungi Difficult to Classify Protista is a “catch - all” kingdom Members differ enormously from one another in morphology and life-styles Molecular and biochemical comparisons help to clarify evolutionary relationships
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6/15/2011 3 Protist Ecological Diversity Protists generally require liquid or moist habitats Have a variety of metabolic lifestyles Photoautotrophs Chemoheterotrophs Parasites Two general categories: protozoans and algae Locomotory diversity Most protists are motile, most utilizing one of three locomotory modes: Amoeboid motion : involves pseudopods Cilia : hairlike projections that beat in concert Flagella : a whiplike organelle that pushes or pulls the organism Flagella Vacuoles Protists employ several type of vacuoles to enable them to survive Contractile vacuoles help regulate water concentrations Digestive vacuoles aid in the digestion of large food particles External surfaces Protists differ considerably in their cell surfaces Some have cell walls, some don’t Others have various methods of strengthening the outer surface Ecological impacts of protists Phytoplankton , photosynthetic protists form the energy base of marine ecosystems
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6/15/2011 4 NORTH AMERICA ATLANTIC OCEAN AFRICA SPAIN Winter Spring NORTH AMERICA ATLANTIC OCEAN AFRICA SPAIN Protists are abundant in the world’s oceans. Photosynthetic marine
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This note was uploaded on 09/08/2011 for the course LS 1 taught by Professor Thomas during the Summer '05 term at UCLA.

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Lecture_8_Protists_and_Fungi - 6/15/2011 Whats a eukaryote?...

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