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Algae:
Class: Cyanobacteriae or the blue-green bacteria (algae)
Where are they
found?
- *temperate polluted
waters
- *fresh & marine
waters throughout the world; unusual are the hot spring species which
lay down travertine (carbonate deposits) and the arctic species which
form 2-4cm mats 5m beneath the ice.
- *warm to moist
soils
- *symbiotic relationships
with amobae, protozoa, diatoms, sea anemones, cycads and with fungi
in the form of lichens
Morphology:
- Chains, branched
hairlike filaments, plates held together by gelatinous sheaths
- Sheaths as well
as the cells themselves-may be pigmented yellow, red, brown, green or
violet:
- Thylakaids are
single membrane
Colors: approx
1/2 of 1,500 known species are blue-green in color due to the pigments
- chlorophyll a (green) and blue (phycocyanin); others are red in color
due to additional phycoerythrin pigment ( ex. Red Sea); others are yellowish
due to carotenoid pigments. This photo depicts
some of the more colorful bg found in hotsprings
Food storage;
* cyanophycin(nitrogenous)
and carbohydrates & lipids. How can they afford this?
Movement:
* NO flagella; filamentous
forms glide by rotating on axis by twisting fibrils insde the cell walls
& secreting a mucilagenous sheath
Reproduction:
- asexual via cell
fission and fragmentation of colonies; in some 9p. at heterocyst (special
colorless larger cell used for N-fix)
- delayed reproduction
via akinetes, resist freezing and stress- can germinate deades later
- no sex in usual
sense (ie gametes); genetic recombination as bacteria
- in symbionts,
wait to divide with host cell; act as chloroplast with no cell wall
Ecological significance:
- Fossils 3.5 BYA;
started to produce oxygen 3 BYA, which allowed the buildup of
ozone, which allowed transition to earth.
- Bottom of food
chain ,
- Blooms:
floating scum in summer, toxic when die and decompose, oxygen levels
drop w/ decomposition; foul water taste and odor.
- There are toxic
forms, hit fish directly or fish ingest and become toxic; mild
- Parasite in
humans and other animals. Clog up water supply filters, soften water
excessively Food to humans limited; Spirulina
- Fix nitrogen-
very important role in oceans may fix 1/4 of N; in human rice paddies
act as fertilizers.Photo of anabena, an important
nitrogen fixing family.
Class: Prochlorobacteriae
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Taken from: http://152.35.128.16/biology/bio101/read26.html
In 1988, Sallie W. Chisholm and a team of colleagues from Harvard
University and Woods Hole Oceanographic Institution reported their
discovery of a strange new kind of photosynthetic cell in six different
ocean areas from the tropics to the North Atlantic. The cells are
prokaryotic (have no nucleus) and are so tiny that the team could
see them only with an electron microscope. They were also incredibly
numerous, with up to 100,000 cells in every teaspoonful of seawater
sampled. The cells have a kind of chlorophyll a never seen before
as well as chlorophyll b, alpha-carotene rather than beta-carotene,
and traces of other pigments. ÊÊÊ
Ê The team places the new cells in the Phylum Prochlorophyta, which
contains species generally thought to be living relatives of the
very early cells that gave rise to chloroplasts. One type of prochlorophyte
called Prochloron, discovered in 1976, grows inside the bodies of
sea squirts and other little marine animals, trading photosynthetic
products for room and board. Some biologists consider ProchloronÕs
symbiosis, its ability to coexist within other organisms, to be
significant, since some similar photosynthetic bacterium probably
entered into communal living with ancestors of plant cells. ÊÊÊÊ
In 1986, researchers discovered a second type of prochlorophyte
- this one free-living - in shallow lakes in the Netherlands. The
new type discovered by the Chisholm team in 1988 is also free-living,
but is perhaps more significant for three reasons: (1) It contains
both chlorophylls a and b, the same pigments in the chloroplasts
of virtually all land plants, a striking evolutionary coincidence,
(2) The internal structure of the new species is quite similar to
the Prochloron cells that live within sea squirts and may, in fact,
be a free-living counterpart resembling the ancient marine cells
that existed independently before coming to inhabit plant cells,
and (3) the newly discovered green cells are so abundant that they
must have great ecological significance as fixers of carbon and
producers of oxygen in the open oceans.
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