Algal Glossary - Under Construction

Alga (-ae) - a term for a very diverse taxonomic group all containing chlorophyll a but lacking vascular tissues found in higher plants; may be unicellular or multicellular organisms, found in marine, freshwater, living endophytically in other plants and algae, soil environments, some can even by airborne.  This course focuses on freshwater algae found in the following phyla: Cyanophyta (blue-greens), Chlorophyta (greens), Euglenophyta (flagellated greens), Pyrrhophyta (dinoflagellates), Chrysophyta (browns, yellow-greens, diatoms) and the Rhodophyta (reds).

Aggregation - a grouping of algal cells but not the organization of a colony, often held together by mucilage
Biflagellate - having two flagella
Chlorophyll - pigment found in photosynthetic organisms, all algae have chlorophyll a; chlorophylls b, c, and d are found in one or more groups of algae
Coenobium - a colony where the number of cells is fixed at the time of reproduction
Coenocyte / Coenocytic - a multinucleate cell that does not have cellular cross walls
Colony - a group of cells that function on one, organized unit such as Hydrodictyon
Cyst - a general term for thick-walled vegetative cell
Desmokont - dinoflagellate with two flagella at the anterior end
Dichotomous - split into two parts
Dinokont - a dinoflagellate with an flagellum circling the middle and a flagella on the posterior end
Epicone - anterior part of a dinoflagellate cell
Epiphyte - an organism that spends part or all of its life cycle growing on a plant
Eyespot - swelled area attached to a flagella that contains pigment.  The pigment proteins respond to the presence of light and signal the flagella to move toward it.
False branching - found in Cyanophyta (blue-greens); appearance of branched cells but when cells are simply adjacent to each other and connected by only mucilage
Flagella - a cellular appendage that enables cells to have motility
Fusiform - narrow shaped cell with a sharp tapering at both end
Heterocysts - specialized cell in Cyanophyta that is able to fix nitrogen
Heterotrichy - a differentiated growing pattern in which some filaments grow appressed to the anchoring surface and others are erect usually in a branch-like pattern.
Intercalary - located within the algal filament or thallus
Lorica - a cell wall covering that has space between the cell wall and the cell membrane, often in Euglenophyta
Mucilage - a  carbohydrate based material found on the outside of some algal cells (see Lyngbya sp.)
Palmelloid formation  - non-flagellated cells in a common mucilage
Paramylon - found in Euglenophyta; carbohydrate source that is long chain of glucose molecules
Parietal - arranged along the cell walls
Pellicle - found in Euglenophyta; a series of strip-like plates underneath the cell membrane arranged in a spiral, pellicle may be rigid or plates may be able to slide as the cell expands and contracts during movement.
Pyrenoid - protein region inside chloroplast that accumulates carbohydrates
Sheath - thin mucilaginous covering over a filamentous algae
Stellate - star-shaped
Theca - cellulose plates that are "armorlike" in appearance found in Pyrrhophyta (dinoflagellates)
Terminal - located at the end algal filament or thallus
Trichome - in Cyanophyta; the cells making up a filament
True Branching - found in Cyanophyta (blue-greens); trichome branches (compare to false branching)


Reproductive terms
akinete - a thick-walled, resting, vegetative cell that can withstand environmental stresses such as temperature (asexual reproduction)
anisogamy - sexual fusion between flagellated gametes of distinctly different sizes and morphologically different
aplanospore - non-flagellated spore (asexual reproduction)
autocolony - a newly produced coenobium with the same form as the parent colony (asexual reproduction)
autospore - internal spore formed by cell division within a mother cell forming a replica of the mother cell, not flagellated (asexual reproduction)
binary fission - a single cell doubling it's nuclear material and then dividing into two cells (asexual reproduction)
coenobium - a group of cells forming a structured, fixed colony such as Scenedesmus
conjugation - sexual fusion of two ameboid cells (motile is from ameboid movement not flagella). two types
    lateral conjugation - adjacent cells in the same filament conjugate
    scalariform conjugation - cells in two separate, parallel filaments conjugate (most common)
hormogonium - short segment of cells that separates from the end of a trichome and initiates a new trichome in some Cyanophyta (asexual reproduction)
isogamy - sexual fusion between flagellated gametes of same size and similar morphology
macrandrous condition - development of a thickened cell that becomes the oogonium
nannandrous condition-  a small side appendage next to the oogonium that.  Small spores are released by the male filaments that are attracted to the oogonium.
oogamy/oogamous - sexual fusion between a flagellated gamete (sperm/antherozoid) and a non-flagellated gamete (egg).
planospore - flagellated spore (asexual reproduction)
spore - asexual reproductive cell
vegetative propagation/reproduction - when part of the algal body breaks off and two new bodies grow (common in filamentous algae)
zoospore - a flagellated spore (asexual reproduction)


Diatom Terminology
Centric diatom - radially symmetric diatom; compare to pennate diatoms
Costa - a thickened portion of a diatom wall, usually elongated
Epitheca - larger valve of a diatom cell wall (frustule)
Frustule - cell wall of a diatom
Girdle view - "side" view of a diatom
Hypotheca - the large or lower valve of a diatom cell wall (frustule)
Pennate diatom - bliaterally symmetric diatom
Pseudoraphe -  clear line down the middle of a diatom created by the lack or ornamentation
Raphe -  linear slit in the valve
Striae - ornamental lines on the cell wall (frustule)
Valve view - "top" view of a diatom

Valve view of radially
symmetric diatom (Centrales)

Girdle view showing epitheca, girdle(band) and hypotheca

Valve view of bliaterally symmetric diatom (Pennales)
Valve view showing difference betwen raphe and pseudoraphe

 
 
 

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