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Overview and 28.1

Overview and 28.1. Elyse Smilnak. Vocabulary. Protists Mixotrophs Endosymbiosis Algae Secondary endosymbiosis. Overview. Protists – incredibly small, unicellular group of eukaryotes First discovered by Dutch microscopist Antoni van Leeuwenhoek Various shapes and forms

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Overview and 28.1

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  1. Overview and 28.1 Elyse Smilnak

  2. Vocabulary • Protists • Mixotrophs • Endosymbiosis • Algae • Secondary endosymbiosis

  3. Overview • Protists – incredibly small, unicellular group of eukaryotes • First discovered by Dutch microscopistAntoni van Leeuwenhoek • Various shapes and forms • Move with flagella or with blob-like appendages • Shaped like trumpets or strings of jewelry • Were once classified as their own kingdom: Protista

  4. Most Eukaryotes are Single-celled Organisms • Eukarya Domain • Eukaryotes • Nucleus • Membrane-bounded organelles • Main Points: • Organisms in most eukaryotic lineages are protists • Most protists are unicellular

  5. Structural and Functional Diversity in Protists • Structurally and functionally diverse • Use some of the same organelles: nucleus, endoplasmic reticulum, Golgi apparatus, and lysosomes • Contractile vacuoles – pump excess water from the cell • Photoautotrophs, heterotrophs, and mixotrophs – combine photosynthesis and heterotrophic nutrition • Asexual, sexual

  6. Endosymbiosis in Eukaryotic Evolution • Endosymbiosis – the process in which certain unicellular organisms engulf other cells, which become endosymbionts and ultimately organelles in the host cell • Eukaryotes acquired mitochondria by engulfing an aerobic prokaryote(alpha proteobacterium) • Algae – photosynthetic protists • Red and green algae • Secondary endosymbiosis – red and green algae is ingested in the food vacuoles and becomes endosymbionts themselves

  7. Diversity of plastids produced by endosymbiosis. Studies of plastid-bearing eukaryotes suggest that plastids evolved from a gram-negative cyanobacteria that was engulfed by an ancestral heterotrophic eukaryotic (primary endosymbiosis). That ancestor then diversified into red algae and green algae, some of which were subsequently engulfed by other eukaryotes (secondary endosymbiosis). Diversity of Plastids Produced by Endosymbiosis

  8. Five Supergroups of Eukaryotes • Excavata • “excavated” groove on one side of the body • Chromalveolata • Include important pathogens and photosynthetic organisms such as brown algae • Rhizaria • Contains many species of amoebas with thread-shaped pseudopodia • Archaeplastida • Includes red and green algae and land plants • Unikonta • Ameobas with lobe- or tube-shaped pseudopodia, animals, and fungi

  9. Protistan Diversity

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