Protists

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Protists

• Chapter 29

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Domain EukaryaKingdom Protista

• Protists are the most diverse of the four
  eukaryotic kingdoms
• -Unicellular, colonial and multicellular groups
• The Kingdom Protista is paraphyletic
• Some protists are surrounded by Extracellular
  Material deposited outside of the plasma membrane

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15 Major Phyla ... 7 Monophyletic Groups that
may actually be Superphyla, Phyla, Classes, or
Orders
-The 15 major protist phyla are grouped into
seven major monophyletic groups -However, 60
lineages cannot be placed with confidence
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15 Major Phyla ... 7 Monophyletic Groups that
may actually be Phyla, Classes, or Orders
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Eukaryotic Origins

• Eukaryotic cells differ from prokaryotes by the
  presence of a cytoskeleton and organelles
• Appearance of eukaryotes in microfossils occurred
  about 1.5 BYA

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Eukaryotic Origins

• The nucleus and endoplasmic reticulum arose from
  infoldings of prokaryotic cell membrane

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• Many organelles evolved via
• endosymbiosis between an
• ancestral eukaryote and a
• bacterial cell

Over time, most organellar genes moved into the
nucleus -Therefore, these organelles cannot be
grown in pure culture
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Secondary endosymbiosis -Red and green algae
engulfed cyanobacteria -Brown algae ancestor
engulfed red algae
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General Biology of the Protists

• Nutrition
• -Phototrophs
• -Heterotrophs
• -Phagotrophs Particulate food matter
• -Osmotrophs Soluble food matter
• Uptake of dissolved organic
  compounds by osmosis for nutrition.
• -Mixotrophs are both phototrophic and
  heterotrophic

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General Biology of the Protists

• Asexual reproduction
• -Typical mode of reproduction
• -Some species have an unusual mitosis
• -Binary fission Equal cells
• -Budding Progeny cell smaller
• -Schizogony (skitz-awe-gony) Multiple fission
  of nucleus and then cytoplasm
• Sexual reproduction
• -Union of haploid gametes which are produced by
  meiosis

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Order Diplomonadida Class Parabasalia

• -Are closely related to the early, now extinct
• eukaryotic cell
• -Flagellated

-Lack mitochondria May have lost it
Diplomonads -Have two nuclei -Giardia
intestinalis
Parabasalids (Par-uh-bay-sil-ids) -Have
undulating membranes -Trichomonas vaginalis
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Phylum Euglenozoa (you-glee-no-zo-uh)

• Euglenoids were among the earliest eukaryotes to
  possess mitochondria
• -1/3rd have chloroplasts

-All have a flexible pellicle
(cell membrane support...protein strips under
cell membrane tough flexible)
This is a picture of a specimen from Genus
Euglena
-Stigma Movement towards light
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Phylum Euglenozoa

• Class Kinetoplastida (Kinetoplastids)
• -Kinetoplast DNA inaA unique, single
  mitochondrion with 2 types of DNA, maxicircles
  and minicircles (expressed genes are used in RNA
  editing and glycolysis)
• -Family Trypanosomatids (trypanosomes) cause
  human diseases
• -African sleeping sickness Tsetse (set-see)
  fly
• -Escapes immune systems because only one of
• 1000-2000 variable antigen genes is
  expressed at a
• time on the glycoprotein coat

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Superphylum Alveolata (al-vee-oh-luh-ta)

• Alveolata have flattened vesicles called alveoli
• -These function like Golgi bodies below the cell
  membrane

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Superphylum Alveolata

• Phylum Dinoflagellates
• -Unicellular with two unequal flagella (encased
  by cellulose-like material with silica)
• -Live in aquatic environments
• -Most are photosynthetic

-Reproduction is primarily asexual -About 20
species produce powerful toxins that harm
vertebrates...Blooms are responsible for red
tide--kills marine vertebrates
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• Superphylum Alveolata
• Phylum Apicomplexa....Apicomplexans
  (Spore-forming animal parasites)
• Genus Plasmodium
• -An apicomplexan that causes malaria
• -Organism has a very complex life cycle

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Superphylum Alveolata

• Phylum Ciliophora (Ciliates)
• Genus Paramecium
• -Have two types of nuclei
• -Macronucleus Divides by mitosis...after
  asexual reproduction
• -Responsible for physiological functions
• -Micronucleus Divides by meiosis
• -Involved in a nucleus exchange conjugation
• -Fusion of two nuclei from cells of different
  
• mating types creates a new diploid
  nucleus

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Genus Paramecium
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(Alveoli form supportive pellicle)

• -Food vacuoles Digestion of food
• -Contractile vacuoles Regulation of water
• balance
• Killer strains have an endosymbiotic bacterium.
  If non-killer strains
• take it up, the toxin in the bacteria is
  released.

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Phylum Stramenopila (stra-men-awe-pil-uh)

• Stramenopiles (....awe-pil-eez) have very fine
  hairs on their flagella during motile life cycle
  stage

-A few species have lost their hairs during
evolution
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Phylum Stramenopila

• Class Phaeophyceae (Brown algae)
• -Kelps
• -Grow in relatively shallow waters throughout
  the world

-Life cycle involves alternation of generations
-Sporophyte Multicellular and
diploid -Gametophyte Multicellular and haploid
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Class Phaeophyceae (Brown algae) -Kelps
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Phylum Stramenopila

• Diatoms (Subphylum Chrysophyta, Class
  Bacillariophyceae)
• -Unicellular organisms(photosynthetic)
• -Have unique double shells made of opaline
  (oh-pa-lean) silica
• -Some move using raphes (Pronounced
  "RAY-fee")--lined with vibrating fibrils

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Phylum Rhodophyta
Rhodophyta, or red algae, range from microscopic
to very large sizes (ice cream, sushi rolls,
makeup). Carrageenan (polysaccharide food
additivehas toxicity) -Have accessory
photosynthetic pigments within phycobilisomes
(phyco-bile-e-sohm)
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Class Choanoflagellatea

• Choanoflagellates are most like the common
  ancestor of all animals
• -Single emergent flagellum, surrounded by
  funnel-shaped contractile collar
• -Use collar to feed on bacteria

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Protists Without a Clade

• Amoebas are paraphyletic
• -Phylum Rhizopoda (rye-zawe-ped-uh)
• (True amoebas)
• -Move by means of cytoplasmic projections
  called pseudopods
• -Phylum Actinopoda (actin-awe-ped-uh)
  (Radiolarians)
• -Glassy exoskeletons made of
• silica
• -Needlelike pseudopods

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Protists Without a Clade

• Phylum Foraminifera (for-rah-mi-ni-feruh) are
  heterotrophic marine protists
• -Have pore-studded shells (eg ca
  carbonate)called tests, through which thin podia
  emerge (for swimming and feeding)
• -Have complex life cycles with haploid and
  diploid generations
• -Limestones
• are rich in forams
• fossils
• -White cliffs
• of Dover

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Slime molds w/o a clade

• 1. Phylum Myxomycota, Plasmodial slime molds
• -Stream along as a plasmodium, a nonwalled,
  multinucleate mass of cytoplasm
• -Ingests bacteria and other organic material
• -When food or moisture is scarce, organism forms
  sporangia, where spores are produced

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Slime molds w/o a clade

• 2. Phylum Acrasiomycota Cellular slime molds
• -Individual organisms behave as separate amoebas
• -Move through soil ingesting bacteria
• -When food is scarce, organisms aggregate to
  form a moving slug via cAMP signal
• -Slug differentiates into a sorocarp with spores
  that differentiate into amoebas again