BIOLOGY

The Protists

Water Molds, Slime Molds, Chytrids, and Unicellular Algae.

Concepts/Ideas/Facts:

1. autotrophic groups are not directly related to each other.
2. heterotrophic store their food as glycogen
3. green alga store food as starch

Definitions:

1. Phycologist – scientists who study algae
2. Protozoologist – scientists who study protozoa
3. Phytoplankton – suspended in water planktonic algae and cynobacteria
4. Nanoplankton – smallest members of the phytoplankton
5. Zooplankton – the heterotrophic plankton
6. Oomycota – water molds – have flagellated stages
7. Chytridiomycota – the chytrids – have flagellated stages
8. Acrasiomycota – cellular slime molds
9. Myxomycota – plasmodial slime molds
10. Myxameba – feeding stage of a uninucleate cellular slime mold when they feed and move like an ameoba
11. Floidean Starch – unique molecule that resembles the amylopectin portion of true starches and is more like glycogen than starch
12. Laminariaglucose – containing polysaccharide, which has linkage between the glucose units that is different.
13. Paramylon – a helical configured polysaccharide
14. Homothallic – having male and female sex organs borne on the same individual
15. Heterothallic – male and female sex organs are borne by different individuals, or, if they are borne on the same individual, that individual is genetically incapable of fertilizing itself.
16. Antheridiol – in water mold, sex hormone secreted by the female hyphae that induces the initial development of antheridia on the hyphae of the male organism.
17. Oogoniol – in water mold, sex hormone secreted by the male hyphae that induces the formation of oogonia on the hyphae of the female organism.
18. Fucoxanthin – golden-brown carotenoid pigment found in Chyrsophytes.
19. Frustule – silica, outer shell-like covering of a diatom
20. Raphe – long groove or slit in the shell or frustule of a diatom
21. Zooxanthellae –thecae lacking, symbiotic form of a dinoflagellate which produce glycerol rather than starch.
22. Hystrichospheres – dinoflagellate zygotes
23. Coenocytic – referring to filaments without internal cross walls
24. Zoospore –haploid gamete of molds

Oomycota: primarlily an aquatic protist, which range from a unicellular form to a highly branched coenocytic filamentous form.  Cell walls are composed largely of cellulose or cellulose-like polymers.  Oomycetes are parasitic or saprophytic and caused the Irish potato blight.

1. Oogonium – a unicellular female sex organ that contains one or several eggs
2. Antheridium – a sperm (male) producing organ, which may be multicellular or unicellular
3. Oospore – thick walled zygote of Oomycota, which acts as a resting spore
4. Oogamy – sexual reproduction in which one of the gametes (egg) is large and nonmotile, and the other gamete (sperm) is smaller and motile

Characteristics of Oomycota:

1. cell walls composed largely of cellulose or cellulose like polymers
2. centrioles occur during meiosis
3. range from unicellular to highly branched, and filamentous
4. reproduce both asexually and sexually
5. have flagella
6. coenocytic

Characteristics of Chytridiomycota:

1. Primarily an aquatic protist
2. cell wall includes chitin
3. most coenocytic, with few septa at maturity
4. zoospores and gametes are motile, having a single, posterior, whiplash flagellum
5. most unicellular but some multicellular
6. both parasitic and saprobic

Acrasiomycota:

1. Acrasiomycota – a terrestrial, cellular slime molds that exist as free-living amoeba-like cells in litter-rich soils.  They feed on bacteria, have cellulose rich cell walls, and undergo normal mitosis in which the nuclear envelope breaks down.  Cellular slime molds have centrioles.
2. Pseudoplasmodium – the aggregation of individual acrasiomycota cells into a slug-like motile mass, which moves to a new area of habitation and form a sporangia that produces spores.
3. Macrocysts – flattened, irregularly circular or elliptic, multicellular sexual structures within which the diploid zygote undergoes meiosis and mitosis before germination.

Myxomycota: Primarily a terrestrial protist

1. Plasmodium – multi-nucleated, membrane bound cytoplasm , cell-less, naked mass of myxomycota protoplasm which move and digest various bacteria, yeast cells, fungal spores and so on.  Cells do not undergo cytokinesis thus remain a multinucleated cytoplasm.
2. Plasmodiocarp – occurs when the entire plasmodium develops the most primitive type of fructification.  It is the sessile, branched, ring-shaped, or netted type of fruiting body formed when a plasmodium becomes concentrated in its main veins during fruiting.
3. Aethalium - are large, thickened, mound or cushion-shaped structures containing numerous spores.  The large spore bearing mass of myxomycota.
4. Sclerotium – encysted stage of plasmodia triggered by adverse environmental conditions such as drought.

Chrysophyta:

1. Chrysophyta – autotrophic, unicellular, aquatic organisms that have chlorophyll a and c
2. Chrysolaminarin – polymerized form of the polysaccharide laminarin
3. have unequal flagella
4. have naked cell or have cell walls made up of cellulose

Classes of Chrysophyta:

1. Chrysophyceae (golden algae) – flagellated, unicellular organisms which lack a cell wall but have silica scales or skeletal structure.  Have chlorophyll.
2. Bacillariophyceae (Diatoms) – unicellular organisms which lack flagellum but have plastids that contain chlorophylls a and c as well as fucoxanthin.  Diatoms have a unique shell of silica called frustules.  They reproduce asexually by cell division.
1. Pennate Diatoms – bilaterally symmetrical diatoms in which sexual reproduction is isogamous, and both male and female gametes are nonflagellated
2. Centric Diatoms - radially symmetrical diatom which have a larger surface-to- volume ration than pennate diatoms and consequently float more easily.  Centric diatoms have oogamous sexual reproduction.  Gametes at this time may have a single tinsel flagellum: the only flagellated cells found in the diatoms at any stage of the life cycle.
3. Zanthophyceae (yellow - green algae) – have chlorophyll c but no fucoxanthin

Dinoflagellates:

1. Dinoflagellates – unicellular biflagellates, one flagellum encircling the body like a belt, while the second flagellum is perpendicular to the first.  They have a stiff cellulosic plates forming a wall (theca) which are formed inside the plasma membrane.  The food reserve in dinoflagellates is starch.  They have chlorophyll a and c.  Dinoflagellates occur as symbionts in many other species and when they are symbionts they lack thecae and appear as golden spherical cells called zooxanthellae.

Euglenoids

1. Euglenophyta – fresh water unicellular organism except the genus Coacium.  Euglenoids store their carbohydrates food reserves in the form of the polysaccharide parmylon which is not found in any other group of organisms.  Some are autotrophic and others are heterotrophic.  They reproduce by cell division, with individual cells remaining motile.  The nuclear envelope remains intact during mitosis.  They have no cell wall.  There is no known sexual reproduction ineuglenoids.
2. Reservoir – area at the base of the flask-shaped opening at the anterior end of the cell where the flagella are attached.
3. Pellicle – structure made of flexible, interlocking, mostly proteineous strips that are arranged helically together with the plasma membrane.