Lecture 14 Protists Flashcards
- Prominent members of ecosystems
- Useful as model systems and in industry
- Some are human and plant pathogens
- among the 20 most frequent microbial causes of death world - wide, 6 are eukaryotic
- Two groups : Protists and Fungi
Eukaryotic Microorganisms
Organelles of Eukaryotic Cells
- Endoplasmic Reticulum
- Protein synthesis - ribosomes
- Golgi Apparatus
- Chemical modification, packaging, secretion
- Mitochondria
- Powerhouses of cell - ATP by e transport and oxidative phosphorylation
Importance of Protists
- Important link in food chains
- Plankton in aquatic habitats
- Radiolarians, Diatoms and Foraminiferans
General Features of Protists
- Terrestrial or aquatic
- Some parasitic in humans, animal sand plants
- Motile
- Flagella, also cilia and pseudopodia - Reproduction:
- Sexual and/or Asexual
Micronucleus
-“true nucleus”, normal chromosomes, mitosis
Macronucleus
- thousands of short, linear chromosomes
- Genes for growth and feeding
Trichocysts
- Filament projections
- Ejected
- Defense , Food Capture
- Seath the Scaleless
Metabolism
- can be photosynthetic (oxygenic)
- also chemoorganoheterotrophs and mixotrophs (organic and inorganic)
Nutrition
- Solid nutrients by phagocytosis
- Soluble nutrients by facilitated diffusion and active transport
Encystment
- development into dormant stage -cyst
- protection, transmission
Excystment
-escape from cyst to metabolically active, motile form - trophozoite
- Unicellular green algae
- Cell walls of celulose
- Oxygenic photosynthesis
- Motile via two flagella
- Stigma (eyespot)
- Phototaxis
- Photoreceptors - Potential Biofuel Source
Chlamydomonas
Life Cycle of Dictyostelium A cellular Slime mold
- Nutrition = bacteria by phagocytosis
- Free-living amoeboid cells
- Aggregate to form motile slug
- Signal = cAMP
- Fruiting body with spores
- Spores released
- Protozoan parasite
- Human pathogen, Giardiasis
- Cysts ingested
- Trophozoites attach to intestine
- Disrupts nutrient and water flow
- Severe diarrhea, fluid loss
- Backpackers, if filtering water, ensure filter removes cyst form
Giardia
- Free-living, aquatic, amoeba
- Thermophile - warm, high nutrient, fresh water
- Trophozoite enters nose travels to brain and destroys tissue causing brain swelling and death
-Primary amebic meningoencephalitis
Naegleria fowleri
-Includes the Dinoflagellates, Ciliates and Apicomplexans
Alveolata
Calcium and enzyme release to penetrate host cells
Apical Complex
- Oocysts of ____ transmitted in contaminated water
- Common cause of waterborne disease
Cryptosporidiosis
- small (not easily filtered)
- chlorine resistant
- stable for months
- only 8 - 10 to cause infection
- After ingestion, oocysts undergo excystment become trophozoites in intestine
Oocysts
- Caused by 4 species of Plasmodium
- Plasmodium falciparum
- apical complex
-Transmitted by bite of infected female Anopheles mosquito
Malaria
Describe the process of how a sporozoite penetrates a RBC
- Sporozoites injected into human with saliva of mosquito
- Sporozoite penetrates liver cell
- In the liver, Sporozoites become Merozoites
- Merozoites infect red blood cells (cyclic)
- Parasite forms knobs on RBC surface.
Malaria - Clinical Symptoms
- Periodic chills, fever
- Anemia - disrupted blood flow
- Liver - hypertrophy
Malaria - Control, Prevention, Treatment
- Mosquito control - wetland drainage, insecticides, netting
- Genetically modified mosquitoes
- Drugs
- Chloroquine
- Parasite degrades hemoglobin as nutrient
- Releases toxic heme
- Parasite polymerizes heme into non-toxic form
- Drug blocks polymerization
