Protists

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Protists

• Chapter 28

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What you need to know!

• Protista is no longer considered an independent
  kingdom. They are part of the Eukaryotes doman
  and are very diverse.
• How Chloroplasts and mitochondria evolved through
  endosymbiosis

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Domain Eukarya

• Kingdom Protista (includes)
• Phylum Protozoa (euglena, amoeba, paramecium,
  malaria)
• Phylum Crysophyta (diatoms, golden algae)
• Phylum Pyrrophyta (dinoflagellates)

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Metabolism

• Protists are the most nutritionally diverse of
  all eukaryotes
• Most protists are aerobic, with mitochondria for
  cellular respiration.
• Some protists are photoautotrophs with
  chloroplasts.
• Still others are heterotrophs that absorb organic
  molecules or ingest larger food particles.
• A few are mixotrophs, combining photosynthesis
  and heterotrophic nutrition

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Characteristics

• Protists are eukaryotes
• Can be unicellular, colonial, or multicellular
• Predecessor to other eukaryotes plants, fungi,
  and animals.
• Fossils date back 2.1 billion years
• Some of the most complex cell structures found
• Special organelles contractile organelle
  (primitive excretion, H20 balance), eye spots
  (primitive sight), anal pores (primitive waste
  excretion)

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Specifics

• Types
• Absorptive, protists (fungus-like)
• Protozoa - ingestive, animal-like protists
• Algae - photosynthetic, plant-like protists.
• Important Structures
• Flagella Protists have a flagella or cilia
  during some time in their life cycles.
• The eukaryotic flagella are extensions of the
  cytoplasm with a support of a microtubule system
  (made from tubullin)
• Cilia are shorter and more numerous than
  flagella.

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Reproduction

• protists can reproduce asexually or sexually
• Many protists form resistant colonies (cysts)
  that can survive harsh conditions.
• Protists are the first group to show alternation
  of generation
• Most protists are haploid organisms (n), called
  gametophytes
• Gametophytes produce gametes
• Gametes fuse to form a zygote
• The Zygote develops into a sporophyte (not the
  main organisms)
• The Sporophyte produces haploid spores that
  germinate into gametophytes

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Habitat

• Protists are found almost anywhere there is
  water
• Oceans, ponds, and lakes, but also damp soil,
  leaf litter, and other moist terrestrial
  habitats.
• Protists are also important parts of the
  plankton, communities of organisms that drift
  passively or swim weakly in the water.
• Phytoplankton (including planktonic eukaryotic
  algae and prokaryotic cyanobacteria) are the
  bases of most marine and freshwater food chains.

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Lifestyle

• Many protists are symbiots that inhabit the body
  fluids, tissues, or cells of hosts.
• These symbiotic relationships span the continuum
  from mutualism to parasitism (malaria, giardia)

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Evolution

• Endomembrane system of eukaryotes (nuclear
  envelope, endoplasmic reticulum, Golgi apparatus,
  and related structures) may have evolved from
  in-folding of plasma membrane.
• Mitochondria and chloroplasts were incorporated
  through endosymbiosis

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Euglena

• Freshwater microscopic algae, single celled
  autotrophic organism (phytoplankton)
• Contractile vacuole bladder-like, pulsing
  structure that pumps out excess water that enters
  the cell due to the cell being hyperosmotic in
  fresh water
• Eyespot detection of light direction
• Flagellum movement toward light source

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Amoebas

• Pseudopods extensions of the cytoplasm
• Capturing prey, locomotion
• Heterotrophic
• Movement by pseudopods (false feet) bulging out
  of plasma membrane followed by cytoplasm

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Paramecium

• Coordinated movement through ciliates
• Complex organelles contractile vacuole for
  osmoregulation (pumping out water), oral groove
  (mouth), anal pore (duh)

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Radiolarians

• Skeleton pseudopods to increase surface area

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Foraminiferans

• Beautifully shaped calcium carbonate or silica
  shelled protists

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Malaria (protozoan)

• transmitted by infected mosquito

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Phylum Crysophyta/Diatoms

• Abundant in plankton and sediments
• Have silica shells
• Top and bottom shells fit together like boxes

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Well Known Members

• Infamous
• Giardia
• Trypanosomes
• Malaria
• Cute
• Paramecium
• Amoeba
• Mistaken as other organisms
• Brown, green, and red algae
• Giant Kelp