Protists

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Protists
Diatoms make up part of the diverse group of
protists
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What is a Protist?

• Classified in Kingdom Protista
• Protista means very first
• Loosely related group of micro orgs.
• Believed to evolved 1.5 million years ago due to
  symbiotic relationshipsee next slide
• --Unicellular, Colonial, or Multicellular
• --NOT a plant, animal or fungi
• are the simplest Eukaryotes
• Have a nucleus and membrane-bound organelles

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Endosymbiosis Evolution from Bacteria
Proposed by Lynn Marguilis endosymbiosis/Gaia
Theory Proof separate DNA and extra membranes
around mitochondra and Chloroplasts
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Classification of Protists

• Problem to classify because of diversity
• Basically, protist classification is based on
  mode of nutrition
• Animal Like Protists - Heterotrophic
• Must EAT their food
• Move around like animals
• Ex. Amoeba, Paramecium
• Plant Like Protists - Autotrophic
• MAKE their own food
• Ex. Euglena
• 3. Fungal Like Protists Decomposers/Parasites
• ABSORB their food externally
• Ex. Slime molds

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Animal-Like Protists

• Once called Protozoans First Animals
• Make up 70 Percent of all Human Parasites
• 4 Types of Animal-Like Protists
• Based on how they move
• 1. Zooflagellates use flagella to move
• 2. Sarcodines move by extension in cytoplasm
• Called pseudopodia (false feet)
• 3. Ciliates use cilia to move
• 4. Sporozoans do not move at all

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Sarcodine AnatomyEx Ameoba
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Ciliates

• Use cilia to move and obtain food
• Very organized anatomy
• 2 nuclei macronuclei and micronuclei
• Oral Groove mouth-like structure
• Gullet stomach like structure
• Anal pore waste release
• Contractile vacuole store, pump water
• Pellicle rigid protein cover, anchors flagella,
  cilia
• Trichocysts projections that protect the cell
• Ex Paramecium

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Cilliate AnatomyParamecium
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Figure 28.14c Ciliates Paramecium
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Conjugation in Ciliates

• Typically use Asexual Binary Fission
• If stressed can use Conjugation
• Sexual recombination of genes
• NOT Reproduction (No NEW individuals)
• Actually produces clones!!! Why?
• Meiosis of one micro nucleus in each org
• Two orgs swap new micronuclei
• Macro nuclei dissolve and micro becomes
  macronuclei
• New Macronucleus is part self and part other org
  in both

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Plant Like Protists

• Main Characteristic Chlorophyll
• Green Pigment- traps light, carries out
  photosynthesis
• Evolved from symbiosis of photosynthetic bacteria
  and larger, heterotrophic bacteria
• Commonly called Algae
• Can contain cell wall like plants

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Euglena Anatomy
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DiatomsPhylum Bacillariophyta

• Some of the most abundant orgs on earth
• Produce Silicon in outer cell wall glass like
• Patterns and rigid structures
• In death, cell walls produce Diatomaceous Earth
• Abrasive compound used in toothpaste and
  filtration systems

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Some Plant-like protists have adverse effects

• Algal Blooms High levels of nutrients/wastes in
  water
• Cause rapid rise in of unicelled plant like
  protists
• Chokes environment
• RED TIDE Bloom of Dinoflagellates
• Produce neurotoxins, kills marine life

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Red Tide
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Dinoflagellate which causes Red Tide
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Eco Issues Dealing with Plant-Like Protists

• Great Barrier Reef Largest Reef Ecosystem
• Coral is an Animal that lives in Symbiosis with
  Dinoflagellates
• If water temp rises, Dinoflagellates leave coral
  Bleaches (dies)
• Global Warming(?), ocean temps are higher and
  Coral in Great Barrier Reef is bleaching
• Eco Impact loss of major marine habitat!!!

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Characteristics of Fungi-like protists

• Like Fungi
• Absorb food of dead/decaying organisms
• Look like fungi
• Unlike Fungi
• Lack chitin in cell walls
• Have centrioles

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3 Broad Groups of Fungi Like Protists

• Cellular Slime Molds
• --Found in damp, organic soils
• --Play key role in recycling matter
• --Distinct cell membranes during all life stages
• Acellular Slime Molds
• --Enter stage where many cells fuse to form one
  large cell with many nuclei cant tell where
  one starts and another begins
• Water molds
• --Thrive on dead or decaying matter in water or
  can be plant parasites on land in times of heavy
  rainfall

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Acellular Slime Mold
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Water Mold
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Ecology of Fungi Like Protists

• Slime molds and water molds are MOST important
  recyclers of organic material
• Some can be harmful
• Plant diseases ex. Irish Potato Famine water
  mold
• Phytophtora infestans
• overgrowth of water mold caused by wet and
  cool conditions
• Why is the earth not littered with dead orgs?
• Tissues broken down by Fungi Like Protists and
  other decomposers