Lecture #9-2/8 Dr. Kopeny

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1 Lecture #9-2/8 Dr. Kopeny Protistans, Part 1 Lecture VIII Protistans Lecture Themes structure and function; recurring evolutionary themes and unifying features the origin of mitochondria and chloroplasts Impact of Protists on Human Health and Welfare The key to understanding the protists is to recognize that a series of important innovations occurred, often repeatedly, as eukaryoites diversified. (Freeman 2002)

2 Source: Freeman (2002) surface waters teem with microscopic protists In some near-shore areas, gigantic protists from underwater forests Protists are particularly abundant in tidal habitats Morphologies and lifestyles found among protists. Protists are abundant in a wide variety of aquatic habitats. In marine environments, they are found in open ocean as well as in near-shore intertidal habitats (Freeman 2002) Euglena Eugleazoa includes both photosynthetic and heterotrophic flagellates. Most are autotrophic, but the lineage includes Trypanosoma

3 Ciliates dinoflagellates Alvoelata are unicellular, and bear a cavity called and alveoli. Diverse in body form. Apicompla water molds diatoms brown algae Stramenopilan are a diverse lineage of heterotrophs and phothynthetic forms (algae). The name refers to fine hairs on the flagella of members of this lineage

4 Rhodophyta are red algae unlike other eukaryotic algae, they lack flagella at any stage in their life history. They are the most abundant algae in tropical coastal areas Dulce, a large, edible red algae Volvox colonies Sea lettuce Green Algae and Plants evolved from a common photoautotrophic ancestor. Over 7000 species, mostly fresh water. Desmid

5 Choanoflagellida Flagellate protists. Possible ancestor to Sponges to Animals.

6 Size and Structure of Eukaryotic Cells compartmentalization and differentiation makes large size possible. Problem: transport and exchange limitations with increasing size Solution: compartmentalization Example: Paramecium Eukayotic compartments; nucleus, peroxisomes, mitochondria, chloroplasts, central vacuole, golgi, rough ER, smooth ER Paramecium, a predaceous protist that feeds on prokaryotes and other protists Nutritional and Metabolic Diversity in Protists Ingestive Lifestyles: Predation and Scavengers Absorbtive Lifestyles; Decomposers and Parasites Photosynthetic Lifestyles; Producers, many of which are symbionts Photosynthetic unicellular dinoflagellates Paramecium giant kelp Giardia, a unicellular human parasite

7 Predation and Scavenging Parasitism pseudopodia engulf food Ciliary currents sweepd food into gullet host parasite the parasite is a red algae with nonpigmented cells Symbiosis Photosynthetic pigments host symbionts Green cells are dinoflagellates inside a heliozoan Red: chlorophyll a and phycobilins Brown: chlorophyll a and chlorophyll c Green: chlorophyll a and chlorophyll b Many photosynthetic groups of algae are distinguished by the accessory pigments they contain, in addition to chlorophyll a. Each of these accessory pigments interecpts different wavelengths of light Consider the diversity of feeding modes in the lineage Alveolata Ciliates -many predators and herbivores -some parasite/basorbers (eg cattle guts, fish gills) -some feed via symbiotic photosynthesizers Dinoflagellates -half or so are photosynthetic, many others are parasitic Apicomplexans -most apicomplexans are parasitic Feeding diversity in protists, like electron donor and electron acceptor diversity in prokaryotes, no doubt drove phylogenetic diversification

8 Locomotion and Structures for Support and Protection Modes of Locomotion in Protists Pseudopodia An Amoeboid Protist flagella cilia Structure of microtubules in cilia and flagella A ciliatedprotist 2 single microtubules (red) surrounded by nine paired microtubules (yellow)

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10 A ciliated protist reference: chapter 4 in textbook