THE PLANT-LIKE MICROSCOPIC PROTISTS Flashcards
Using nucleic acid sequencing and detailed comparisons of cell structure, systematists have recently begun to sort out the group of organisms known for decades as the
protists.
three domain system
Bacteria, Archaea, Eukarya)
efer to organisms that are neither plant, animal nor fungi but exhibit their characteristics.
Protista
are all eukaryotic but vary in structure and function more than any other group of organisms.
Most unicellular but some are colonial and multicellular.
Many are incredibly complex; within a single cellular membrane the organism must carry out the myriad of life functions performed by the complex tissue and organ systems of plants and animals. Some are autotrophic, others completely heterotrophic.
Protists
Division
Clade
is distinguished from all other protists by the presence of a spiral or crystalline rod of unknown function inside their flagella.
Division Euglenophyta
Clade Euglenozoa,
They are single-celled organisms, usually 35-55 um long, spindle-shaped or elongated; shape is maintained by an outer boundary of protoplast, the pellicle or periplast. They are able to greatly distort their body to change direction.
flagella, typically two (2),
They have a reddish eyespot (=stigma) and contractile vacuole near the reservoir. Their numerous chloroplasts contain several photosynthetic pigments
Nucleus lies in the less viscous cytoplasm.
Euglena.
distortion of Euglena
euglenoid motion
The flagella of Euglena, typically two (2), arise from the base of reservoir and pass through narrow passage called
gullet.
photosynthetic pigments of Euglena
chlorophyll a and b, beta-carotene and xanthophyll
Storage products of Euglena
are starch-like polysaccharides, paramylum and oils.
may occur as discs, rings, rods or spherical granules in cytoplasm.
Paramylum
Euglena thrive best where
thrive best where there is an abundance of organic wastes, where water has brown or green color, also in calm waters.
Division
Clade
include the apicomplexans, ciliates and dinoflagellates, all of which are characterized by membrane-bounded sacs (=alveoli) just under the plasma membrane.
Division Pyrrophyta
Clade Alveolata
function of ____ in Pyrrophyta is unknown but researchers hypothesize that they may help stabilize the cell surface or regulate the cell’s water and ion content.
alveoli
important members of the plankton in both fresh and marine waters, although there is greater diversity among the marine species.
photosynthetic protists are so-named because of their two whip-like flagella, which in many species project through cellulose walls that resemble armor plates.
dinoflagellates
Many are bioluminescent, producing brilliant green light when disturbed. The chlorophyll is masked by red pigments that help trap light energy.
dinoflagellates
When dinoflagellates so numerous, the water is dyed red by the color of their bodies causing
red tides
spp causes the recurring red tide phenomenon along Manila Bay.
Pyrodinium bahamense var. compressum
dinoflagellate’s epicone and hypocone divided by transverse girdle or cingulum, its longitudinal sulcus running perpendicular to the girdle, its longitudinal and transverse flagella, and its eyespot and nucleus.
Pyrodinium bahamense var. compressum
Division
Clade
diatoms, water molds, the golden-brown algae and the multicellular brown algae. A diagnostic characteristic of this clade is the flagellum with numerous fine, hair-like projections (=tinsel-type flagellum).
Division Bacillariophyta
Clade Stramenopila
are classified under Clade Stramenopila
200,000 extant species
mostly unicellular, some diatoms form colonies.
possess siliceous walls in two overlapping sections. The walls are a delicate lacework of holes and grooves that differentiate each species.
diatoms
overlapping sections of diatoms
valves
The larger valve above in diatoms
epitheca
smaller valve below in diatoms
hypotheca.
epitheca hypotheca together make up the _____ and are joined together by connecting or girdle bands.
frustule
in diatoms there are 2 views, valve and girdle views which show the
top or “face” and the side or edge, respectively
two morphological forms of diatoms:
centric
pennate
those possessing radial symmetry range from round, capsule-like or drum-shaped and those with bilateral symmetry have an elongate axis.
Photosynthetic pigments of diatoms include
chlorophylls a and c, carotene, xanthophylls and fucoxanthin
Storage products of diatoms
oils and chrysolaminarin
Diatoms reproduction
mostly reproduce by mitosis. Sexual reproduction is not common. When it occurs, it involves the formation of eggs and sperms. Sperms may be amoeboid or flagellated.
Division
Clade
have their pigments localized in chromatophores that are yellowish green to golden brown because of a predominance of carotenes and one or two xanthophylls that mask chlorophyll a.
Division Chrysophyta
Clade Stramenopila,
food reserves in Chrysophyta
oil and fat; they do not store starch.
Vegetative multiplication in Chrysophyta of filamentous and colonial forms is accomplished by
fragmentation.
Asexual reproduction in Chrysophyta is carried out by formation of
flagellated zoospores, aplanospores or akinetes
Chrysophyta Gametes are formed in the
Gametes are formed in the oogonium and antheridium.
siphonous, multinucleate microalga but becomes septate at reproduction and if filament is damaged.
Vaucheria.
The filament reaches several centimeters in length. It also has a branched, colourless, rhizoid-like holdfast. Some of its species are partly terrestrial and form coarse, green masses on damp soil, particularly round the edges of ponds, or on the silty shores of salt-marshes; other species are totally aquatic, mostly in fresh water habitats.
Vaucheria