Eukaryotes: Stramenopiles, rhizarians and excavates

• What are the major eukaryote lineages mentioned?

  Stramenopiles, Rhizarians, Excavates, Amoebozoans
• What is a characteristic feature of Stramenopiles?

  Typically have 2 unequal flagella
• What types of organisms are included in Stramenopiles?

  Diatoms, brown algae, oomycetes
• What is the primary function of diatoms?

  Photosynthesis and storage of carbohydrates
• What is a unique feature of diatom cell walls?

  They deposit silica in their cell walls
• How do brown algae obtain their color?

  Through fucoxanthin and chlorophylls
• What is the typical habitat of brown algae?

  Almost all are marine
• What is the role of holdfasts in brown algae?

  They anchor the algae to rocks
• What are oomycetes commonly known as?

  Water molds and downy mildews
• How do oomycetes obtain nutrients?

  By secreting enzymes to digest food
• What distinguishes oomycetes from fungi?

  Oomycetes have cellulose in cell walls
• What are the three primary groups of Rhizarians?

  Cercozoans, foraminiferans, radiolarians
• What is a characteristic feature of foraminiferans?

  They secrete calcium carbonate shells
• How do radiolarians increase their buoyancy?

  Through thin, stiff pseudopodia
• What is a unique feature of excavates?

  Some groups lack mitochondria
• What are diplomonads known for?

  Being intestinal parasites with 2 nuclei
• What is a characteristic of euglenids?

  They have flagella from a pocket at the anterior
• What is the significance of Plasmodium spp.?

  They are known for causing malaria
• How do protists contribute to ecosystems?

  They are critical components and primary producers
• What is diatomaceous earth used for?

  Filtration, polishing, and insecticide
• What is the significance of foraminiferan shells in geology?

  They help classify and date sedimentary rocks
• What are the main characteristics of diatoms?

  • Unicellular, some in filaments
  • Carotenoids give yellow/brown color
  • Photosynthetic storage products: carbohydrates & oils
  • Silica in cell walls, two overlapping pieces
  • Morphologically diverse, symmetrical forms
  • Found in oceans, dominant in phytoplankton blooms
• What are the main characteristics of brown algae?

  • Multicellular, fucoxanthin gives brown color
  • Marine habitat, includes giant kelps
  • Some float in open ocean, others attached to rocks
  • Holdfasts made of alginic acid
  • Used by humans as emulsifiers
• What are the main characteristics of oomycetes?

  • Include water molds and downy mildews
  • Absorptive heterotrophs, secrete enzymes
  • Mostly decomposers, some are parasitic
  • Cell walls made of cellulose, not chitin
• What are the main characteristics of Rhizarians?

  • Include cercozoans, foraminiferans, radiolarians
  • Unicellular, mostly aquatic
  • Long, thin pseudopodia
  • Contribute to ocean sediments
• What are the main characteristics of excavates?

  • Include diplomonads, parabasalids, heteroloboseans, euglenids, kinetoplastids
  • Some groups lack mitochondria
  • Unicellular with flagella
• What are the main characteristics of Euglenids and Kinetoplastids?

  • Unicellular excavates with flagella
  • Mitochondria with disc-shaped cristae
  • Asexual reproduction through binary fission
  • Euglenids can be photosynthetic
• What are the main reproductive strategies of protists?

  • Sexual and asexual reproduction
  • Some have reproduction without sex
  • Alternations of generations
• What are the ecological roles of protists?

  • Critical components of ecosystems
  • Primary producers like phytoplankton
  • Some are endosymbionts, e.g., in coral
• What are the uses of diatoms and foraminiferans in industry?

  • Diatoms: source of petroleum and natural gas
  • Foraminiferans: used for classifying and dating rocks
  • Diatomaceous earth: used for filtration and polishing
• What are the main groups of eukaryotes that are not animals, plants, or fungi?

  • Stramenopiles
  • Rhizarians
  • Excavates
  • Amoebozoans