Ch 18: Protists

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Ch 18 Protists
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Protists

• unicellular
• eukaryotic

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Prokaryotes vs Eukaryotes
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Classification

• 115,000 species
• Major debate regarding how they should be
  classified
• animal-like zooplankton or protozoans
• plant-like phytoplankton
• ?

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Endosymbiotic Theory

• It is believed that protists evolved from a
  symbiotic relationship between different types
  prokaryotic cells
• Chloroplasts resemble cyanobacteria
• Mitochondria resemble aerobic bacteria

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Endosymbiotic Theory 2
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Animal-like Protists

• 4 phyla
• Ciliophora (ciliates)
• - Paramecium
• Zoomastigina (zooflagellates)
• Sporozoa Parasitic - Plasmodium
• Sarcodina - ameoba

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Phyla 1. Ciliophora Ciliates

• Covered in cilia used for locomotion and for
  directing food into the oral cavity
• Most are free-living (not parasites)

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Ex Paramecium
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Structure

• 1. Pellicle cell membrane and underlay (looks
  quilt-like) controls entry and exit from the cell
• Embedded in the pellicle are the
• 2. Trichocysts spiny projectiles used for
  protection

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• 3. Macronucleus controls cells activities
• 4. Micronucleus used in conjugation to mix the
  genetic information

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• 5. Gullet (mouth). Cilia move food particles to
  the end of the gullet where they enter the cell
  by endocytosis. This traps the food particles
  into FOOD VACUOLES.
• The food vacuoles will fuse with LYSOSOMES (sacks
  of digestive enzymes) and be digested.

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ENDOCYTOSIS
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• 6. Anal pore Waste particles leave the cell by
  exocytosis at the ANAL PORE

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Exocytosis
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7. Contractile Vacuoles

• Paramecium live in FRESH water
• Osmosis causes water to move into the paramecium
• The contractile vacuole collects the extra water
  so that the paramecium doesnt lyse

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Osmosis Review
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Reproduction

• Like bacteria, paramecium reproduce mainly by
  BINARY FISSION

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Paramecium Sex

• Again, like bacteria, paramecium will
  occasionally engage in conjugation usually when
  they are stressed.

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• Conjugation is not actually reproduction it
  is a trading and mixing of genetic material but
  no new paramecium are formed. However, new
  combinations of genes are created in both partners

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Phyla 2 Zoomastigina

• Called the zooflagellates since they all move
  around using FLAGELLA
• Many are parasitic
• ?Trichomonas causes intestinal and veneral
  diseases in humans

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Giardia causes beaver fever
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Phyla 3 Sporozoa

• All produce spores
• All are parasites
• All non-motile
• Ex Plasmodium (causes malaria)
• ?

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Sporozoa
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Plasmodium Life Cycle

• 1. Spores transferred to humans through mosquito
  saliva
• 2. Spores grow in liver and blood cells, causing
  them to lyse, releasing toxins (creates fever,
  chills)

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• 3. Mosquitoes pick up Plasmodium in the blood
  when it bites the human
• 4. Mosquitoes become infected with Plasmodium
  eventually, spores form in the salivary glands
  and the parasite is passed on to a new human

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How to Avoid Malaria

• 1. Dont go where there are malaria outbreaks
• 2. In areas where there is malaria, dont get bit
  by mosquitoes
• 3. Chloroquinine will destroy some Plasmodium
  spores
• 4. Most often, countries with malaria try to
  control the mosquito host rather than the
  Plasmodium (insecticides and breeding ground
  removal)

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Phyla 4 Sarcodina

• Use PSEUDOPODS to feed and move around

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Ameoba
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