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Protist Groups

Euglenozoa - euglenoids, kinetoplastids 

  • Euglenoids - 1 of earliest organisms w/ mitochondria
    • 1/3 have chloroplasts, are autotrophic; rest are heterotrophic
    • can become heterotrophic when left in the dark
    • pellicle - flexible structure made up protein strips that change the organism’s shape
    • reproduction through mitotic cell division (nuclear envelop stays intact)
    • stigma - light-sensitive organ that helps Euglenoids move
  • Kinetoplastids - has single mitochondrion in each cell
    • mini/maxi circles of DNA in each mitochondrion
    • trypanosomes - causes African sleeping sickness, East Coast fever, Chagas disease, leishmaniasis
    • able to change antigens on glycoprotein coat to fool antibodies
    • don’t infect the flies that carry them

Alveolata - dinoflagellates, apicomplexes, ciliates 

  • alveoli - space below plasma membrane
  • Dinoflagellates - photosynthetic, w/ 2 flagella
    • spins as it moves
    • cellulose-like material forms plates that surround the cell
    • has chlorophyll a, c, and carotenoids
    • responsible for the “red tides”
    • DNA not combined w/ histone proteins
  • Apicomplexes - spore-forming parasites on animals
    • microaerophils - cells that grow best in low-oxygen, high-carbon dioxide areas
    • Plasmodium - responsible for malaria, best-known apicomplex
    • Gregarines - attaches to intestines of arthropods, annelids, mollusks
  • Ciliates - has large number of cilia
    • heterotrophic, w/ cilia in rows or spirals around the cell
    • 2 nuclei - macronuclei needed for physiological functions, micronuclei needed for sexual reproduction
    • some ciliates die after a number of generations w/o sexual reproduction
    • digestive pathway - gullet >> food vacuole >> cytoproct (pore in the pellicle) >> contractile vacuoles empty waste into the outside
    • conjugation - sexual process where 2 ciliates exchange DNA through cytoplasmic bridge

Stramenopila/Rhodophyta - grouped together 

  • Stramenopila - includes brown algae, diatoms, oomycetes
    • brown algae - alternation of generations; most conspicuous of seaweeds
    • diatoms - photosynthetic, w/ double silica shells; moves w/ vibrating fibrils in raphes
    • oomycetes - parasites or saprobes (feeds on dead organic matter); has 2 unequal flagella on spores
    • responsible for the potato famine in Ireland
  • Rhodophyta - red algae
    • no flagella, centrioles
    • uses alternation of generations
    • related to green algae through chloroplast DNA, but not host DNA

Chlorophyta - green algae, ancestors of plants 

  • Streptophyta >> land plants
  • chloroplasts have a/b chlorophylls and carotenoids (like plants)
  • Chlamydomonas - most primitive green algae
    • 2 flagella for mov’t
    • eyespot w/ 100,000 rhodopsin molecules used to direct mov’t
    • mostly haploid
  • Chlorella - nonmotile, cannot form flagella
  • Volvox - forms colonies in a hollow sphere shape

Choanoflagellida - common ancestor of all animals 

  • has single flagellum surrounded by funnel collar
  • feeds on bacteria through water straining
  • has surface receptor involving phosphorylation just like sponges

protists that are hard to categorize - amoebas, foraminifera, slime molds 

  • Amoebas - uses pseudopods for mov’t
    • cytoplasmic streaming - use of cytoplasm extensions to move, eat
    • can move in any direction
    • Actinopoda - aka radiolarians, secretes silica exoskeletons
  • Foraminifera - heterotrophic marine protists, like tiny snails
    • tests - pore-studded shells
    • podia - cytoplasmic projections used for mov’t/eating
    • used as geological markers, indicators of oil
  • slime molds - has at least 3 different lineages
    • plasmodium - nonwalled, multinucleate cytoplasmic mass
    • divides into lots of small mounds when lacking food
    • sporangium - produces the spores
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