The Protists

The Protists

Distribution
1. Chemoorganotrophic-recycling nitrogen and phosphorus
2. Terrestrial & planktonic forms
3. Parasitic forms cause disease
4. Grow in a wide variety of moist habitats
Morphology
1. Pellicle – support
2. Cytoplasm subdivided into outer gelatinous ectoplasm & inner fluid region (endoplasm)
3. Plasma membrane similar to multicellular plants/animals
4. Vacuoles
  1. Contracile (maintain osmoregulation)
  2. Phagocytic (ingestion of food)
5. Energy production
  1. Photosynthetic protists (*chloroplasts & mitochondria)
  2. Aerobic chemoorganotrophic protists (*mitochondria)
6. Cilia/ Flagella- motility/feeding
Nutrition
1. Protozoa- Chemorganotrophic protists
  1. Saprophytes (nutrients from dead organic matter)
  2. Osmotrophy (absorb soluble products)
  3. Holozoic nutrition (solid nutrients- phagocytosis)
2. Photoautotrophic protists
  1. Strict anaerobes
  2. Photosynthesis I & II
3. Mixotrophic protists
  1. Organic and inorganic carbon compounds used simultaneously
Reproductive cells & structures
1. Asexual (binary fission)
2. Sexual (fusion of gametes in syngamy process)
PROTOZOA
1. Different from…
  1. Slime mold (lack of fruiting body)
  2. Yeast & Fungi (by their motility & lack of cell wall)
  3. Prokaryotes (relatively larger, eukaryote)
  4. Algae (no chlorophyll)
2. Structure
  1. Unicellular, eukaryote
  2. Predatory / parasitic
  3. Some are pathogenic
  4. Colourless & motile
  5. Found in water & soil
3. Nutrition
  1. Dinoflagellates & Euglenoids (capable of photosynthesis)
  2. Foods are obtained through
    1. Ingestion
    2. Phagocytosis
    3. Pinocytosis
    4. Absorption
  3. Mostly are aerobic heterotrophs, some are capable of anaerobic growth
4. Diversity
  1. Microscopic (10-200 micrometer)
  2. Occur singly or in colonies
  3. Some are capable of encystment
  4. May be housed in a shell (lorica) eg: foraminiferans
  5. May be parasitic (Trypanasoma) / symbiotic (Joenia)
  6. May or may not be pigmented
  7. Swim freely/ in contact with a substratum / be sedentary
5. Major groups in Protozoa
  1. Archaezoa
    1. Free living
    2. Parasitic / Pathogenic
    3. Trypanosome gambiense
    4. Flagellated (2 or more)
    5. Freshwater
    6. Move in a whiplike manner
    7. African sleeping sickness in human
  2. Rhizopoda
    1. Amoebas
    2. Phagocytosis- obtain food
    3. Movement-pseudopoda
    4. Cause amobic dysentery in human
    5. Eg: Amoeba histolytics
    6. Habitat- freshwater, marine
  3. Ciliophora
    1. Possess cilia
    2. Presence of gullet/cytosome- ingestion
    3. Balantidium coli- human parasite (Dysentery)
    4. Habitat- freshwater/marine
    5. Best known- paramecium
    6. Nuclei
      1. Micronucleus (inheritance & sexual reproduction)
      2. Macronucleus (production of mRNA)
  4. Apicomplexa
    1. Not motile in mature form
    2. Obligate parasites
    3. Complex life cycle- transmission between several hosts
    4. Plasmodium vivas – causing malaria
    5. Taxoplasma- causing taxoplasmosis
Algae
1. Characteristics
  1. Naked reproduction structure
    1. Asexual (all)
    2. Sexual (some)
  2. Mostly photoautotrophic
  3. Contain chlorophyll
  4. Has a simple morphological construction
  5. Requires water
2. Habitat
  1. Aquatic habitat-fresh water, marine & brackish
  2. Few in dry soils
  3. Acidic habitat
  4. Mostly in moist soils & artificial aquatic habitat
3. Motility
  1. If motile, due to flagella
    1. Single flagella- Euglena
    2. 2/4 polar flagella- Chlorophyta
  2. Non-motile in vegetative stage & form motile gametes only during sexual reproduction
4. Distribution
  1. Terrestrial (moist rocks, trees, soils)
  2. Primarily aquatic
  3. 3 types
    1. Benthic
    2. Planktonic
    3. Neustonic
5. Reproduction
  1. Sexual ( Oogonia, Anthredia)
  2. Asexual
    1. Fragmentation
    2. Spores
    3. Binary fission
6. Ecology
  1. Seaweed- provide habitat, human food
  2. Macroscopic form (phytoplankton- food base for marine food chains)
  3. Primary producers of the oceans
  4. Production of neurotoxins
  5. Algal bloom
7. Taxonomy
  1. Rhodophyta
    1. Reddish colour
    2. Chlorophylls a & d, phycocyanin, phycoerythrin
    3. Red pigment absorb blue light
    4. Store glucose polymers
  2. Chrysophyta
    1. Important in global carbon cycling
    2. Store oil
    3. Chlorophylls a & c
    4. Unicellular
    5. Golden-brown algae
  3. Phaephyta
    1. Brownish colour
    2. Chlorophylls a & c, xantophylls
    3. Macroscopic
    4. Store carbohydrate
  4. Chlorophyta
    1. Chlorophyll a & b
    2. Cellulose cell walls
    3. Store glucose polymers
    4. Green algae
  5. Pyrrophyta
    1. Unicellular plankton
    2. Brownish
    3. Store starch
    4. Cause ‘red tides’- gives ocean a deep red colour
    5. Some produce neurotoxins
    6. Chlorophylls a & c
  6. Euglenophyta
    1. Green colour
    2. Chlorophylls a & b, carotene
    3. Store glucose polymers
    4. Rigid plasma membrane (pellicle)
    5. No sexual reproduction
Slime molds
1. Resemble fungi in appearance & life style
2. Three division
  1. Acrasiomycota (Cellular slime molds)
    1. Individual amoeboid cells (unicellular)
    2. Feed phagocytically
    3. Divide by mitosis and cytokinesis
  2. Myxomycota (Plasmodial slime molds)
    1. Phagocytosized dead material
    2. Saprophytes
    3. Multinucleated
    4. Lack cell wall
    5. Glistening, viscous masses of slime
  3. Peronosporomycetes (water molds)
    1. Some grow in cottony masses on dead algae & animals
    2. Some parasites of fish gills
    3. Plant disease (blue mold & Irish potato blight)
    4. Egg fungi- diploid & no chitin in cell wall
3. Distribution & Function of Molds
  1. Engulf bacteria as predator
  2. As decomposers & consumer in the ecosystem
  3. Recycling of nutrients
  4. Cause disease in plants (tobacco plants, potatoes, grapes)
  5. Moist terrestrial habitats (e.g. soil, decaying wood, dung)

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