Microbiology-Chapter 25

Protistology

the general study of protists

Dictyostelium discoideum (Eumycetozoa) (Supergroup Amoebozoa)

-classic cellular slime mold -Masses called pseudoplasmodium retain their cell walls; under adverse conditions cells aggregate into motile multicellular slugs that form fruiting bodies with spores that can germinate into amoeboid cells

Tubulinea Supergroup Amoebozoa

Widely found in moist environments; Amoeba proteus is commonly used in laboratories

4. Supergroup Chromalveolata

-diverse group including autotrophic, mixotrophic, and heterotrophic protists who derived chloroplasts from archaeplastids

1. Supergroup Excavata

Most primitive and deeply branching eukaryotes; most possess a suspension-feeding groove (cytostome) with a flagellum to create feeding currents

3. Supergroup Rhizaria

Amoeboid cells with filopodia; some filopodia called axopodia are supported by microtubules that protrude from an axoplast and are used for feeding

Phycology

the study of algae

Protozoology

the study of protozoans

Foraminifera (Supergroup Rhizaria)

-Amoeboid with reticulopedia and form calciferous shells; can have algal symbionts -mostly marine, can be capable of denitrification, calciferous shell accumulations cause limestone, chalk, and marble

Trichomonadida (Fornicata) (Supergroup Excavata)

-Anaerobic, no mitochondria, do have hydrogenosomes, and reproduce asexually -Symbionts of digestive, reproductive, and respiratory tracts of vertebrate -Trichomonas vaginalis can cause disease in human genitourinary tract

Fornicata Supergroup Excavata

-Flagella but lack mitochondria, but may have mitosomes -reproduce asexually by binary fission -parasites in fish, pathogens in turkeys, and Giardia in humans causes diarrhea and is a public health concern

Euglenozoa

-Mostly freshwater but can be marine. -Some are photoautotrophic, but most are mainly saprotrophic chemoorganotrophs -Trypanosomes are pathogens, eg Trypanosoma cruzi cause Chaga's disease in Central and South America characterized by peripheral nervous system dysfunction and -T. gamiense and T. rhodesiense cause African sleeping sickness -Pathogenic trypanosomes rapidly change the glycoprotein coating of cell walls, or antigenic variation which helps them invade host cells

Trichonymphida (Fornicata) (Supergroup Excavata)

-Obligate mutualist in the digestive tract of wood-eating insects (termites) -Secrete cellulase to aid animal digestion

Eumycetozoa Supergroup Amoebozoa

-Slime molds -complex morphology, life cycle, and behavior

Myxogastria (Eumycetozoa) (Supergroup Amoebozoa)

-acellular slime molds -live on rotting organic matter, move in an amoeboid fashion, feed by endocytosis -under adverse conditions, fruiting bodies form with stalks and spores; spores germinate to produce haploid amoeboflagellates and eventually zygotes and new plasmodium

5. Supergroup Archaeplastida

-all organisms with a photosynthetic plastid arising from endosymbiosis with an ancient cyanobacterium -the group includes higher plants and protists

Chloroplastida (Supergroup Archaeplastida)

-green algae -phototrophs found in aquatic/soil systems -unicellular, filamentous, and colonial -chlorophylls a and b and carotenoids -store carbohydrates as starch

Apicomplexans (Alveolata) (Supergroup Chromalveolata)

-intra- and intercellular parasites of animals -apical complex at end of cell specially designed to penetrate host cells -sexual and asexual stages of lifecycle -Apicomplexans are infectious, eg Toxoplasma-toxoplasmosis from cat feces or Plasmodium—malaria, a major killer worldwide

Dinoflagellata (Alveolata) (Supergroup Chromalveolata)

-large group of common marine plankton; involved in coral formation; the causative agents of toxic red tides

Alveolata (Supergroup Chromalveolata)

-large group of protists that includes dinoflagellates, apicomplexans, and ciliates -saclike structures called alveoli under their plasma membranes

Stramenophila (Supergroup Chromalveolata)

-largest, most diverse -includes diatoms, brown and golden algae, brown seaweeds and kelp, and chemoorganotrophic öomcytes and labyrinthulids -staple of group is heterokont flagella (straw hair flagella) in a life cycle phase

Ciliates (Alveolata) (Supergroup Chromalveolata)

-many cilia for movement and feeding -coordinate cilia movement -tentacles or expel poison darts (toxicysts) to capture prey

2. Supergroup Amoebozoa

-motility involves pseudopodia (cell extensions) that are rounded (lobopodia), long and narrow (filopodia), or form a mesh (reticulopodia) -lack a cell wall (naked amoebae) or be covered (testate amoebae)

Diatoms (Stramenophila) (Supergroup Chromalveolata)

-photoautotrophs -form silica shells made from two overlapping halves, frustule morphology used for identification -unicellular, colonial, or filamentous; lack flagella -major contributors to carbon fixation in ocean and vital to carbon cycles

Protists

-polyphyletic collection of organisms -unicellular and lack the level of tissue organization found in higher organisms -include protozoans (chemoorganotrophic protists) algae (photosynthetic protists) -found in moist, free-living, freshwater or marine with decaying matter -every protists group has species that live in association with other organisms

Entamoebida Supergroup Amoebozoa

Entamoeba histolytica causes amoebic dysentary, a leading cause of parasitic death