handouts on algae
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HANDOUTS ON ALGAE
1. Algae lack true roots, stems and leaves (with vascular tissues);such a body is called a thallus. Plants with such a body arecalled thallophytes.
2. Have chlorophyll a as their primary photosynthetic pigment.
3. Vascular and supporting tissues have not evolved in the algae.
GENERAL CHARACTERISTICSGENERAL CHARACTERISTICSGENERAL CHARACTERISTICSGENERAL CHARACTERISTICS
4. Possibly the only structures possessed by all higher plants thatnever occur in the algae are:
a protective sterile jacket of sterile cells surrounding thedeveloping gametes, and;
an embryo stage in the life cycle.
HABITATHABITATHABITATHABITAT
1) They are attached to tree trunks or branches, to the bottomof streams, to soil particles, or to rocky intertidal cliffsbattered by surf.
2) They are also found growing symbiotically with other plantsor animals.
3 Al ae occur in the most severe habitats on earth.
4) Probably the most commonly noticed natural urban habitatsfor algae are the sides of glass fish tanks.
5) They are also generally found around leaking faucets and ingarden or park pools that are not kept pure with chemicals.
6) The bloom occurring during the summer on many lakes orthe scum found on ponds is actually algae.
HABIT: (THALLUS ORGANIZATION)HABIT: (THALLUS ORGANIZATION)HABIT: (THALLUS ORGANIZATION)HABIT: (THALLUS ORGANIZATION)
1. Thallus organization: unicellular, colonial, filamentous,
siphonaceous (tubular, coenocytic), membranous (foliose),
generally, multicellular ones lack organized tissues.
2. Filamentous cell division occurs in one plane, with the products
of cell division remaining attached to each other to form a
filament. Filaments can be uniseriate (composed of a single row
.
3. Heterotrichous this is the highly evolved type of habit, with the
thallus consisting of different parts: (1) a prostrate creeping
system anchoring the thallus to the substrate, and (2) a projecting
or erect system composed of usually branched filaments.
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DIVISION CYANOPHYTA:GENERAL CHARACTERISTICS
Prokaryotic
Other terms to designate
blue-green algae:Cyanophycophyta,Cyanochloronta,Myxophycophyta, and
Reproduction in blue-green algaeis by cell division in theunicellular species and byfragmentation in the colonial andfilamentous ones.
Some blue-green algae produceminute spores (exospores).
.
Pigments chlorophyll a, a-phycocyanin (blue), c-phycoerythrin (red), betacarotene, several
xanthophylls Stored food or reserved food
cyanophycean starch
Photoautotrophic
Sexual reproduction by union ofgametes to form zygotes hasnot been observed in blue-greenalgae.
Although not flagellated almostall species show the ability forslow motility like gliding or slowwaving of the apical cell.
Specialized cells Heterocysts barrel-
shaped, enlarged cells with
thickened walls, transparentprotoplasm. Site ofnitrogen fixation.
Separation disc double concavediscs of gelatinous materialformed between two adjoining
vegetative cells; separatestrichomes into hormogones.
Separationdisc
Specialized cells
Akinete a thick walled non-motile spore derived from avegetative cell, give rise tofilaments.
Filament refers to bothtrichome and its enclosingsheath
Trichome chain of cells
Habit (thallusorganization)
Unicellular
Colonial non-coenobic
Filamentous filaments are
composed of a chain of cellsthe trichome and the sheath,unbranched, false branched, Unicellular organisms
true branched. .
Frequently encountered onmoist rocks and walls and onflowerpots in greenhouses.
The sheaths may be colored inthe living cells and usually are
thicker and more prominent. Its colonies are complex since
it is composed of moreindividual cells.
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FilamentousOscillatoriasp.
Occurs floating in aquatichabitats or on damp soil.
Exhibit an oscillating motion,as well as rotation andforward and backwardmovement along their longaxes.
Anabaenasp.
A genus that contains bothplanktonic species and some thatform coatings on other aquaticvegetation is widespread inbodies of fresh and salt water.
Have heterocysts and akinetes. Endophytic
All the cells of the trichomeare capable of divisionresulting in an increase intheir size.
Nostocsp. Commonly known as starjellyor witches
butter The plant mass may be spherical, ovoidal, or
sheetlike.
Have heterocysts and akinetes Endophytic
Filamentous
Scytonemasp. A genus widely distributed on
moist rocks and soil, where itforms dark, blackish, feltycoatings.
Its sheaths are thick, firm,sometimes lamellated and
yellow-brown in older partsof the plant body.
False branching takes place.
Rivulariasp.
False branching also takes place, itdiffers from Scytonemain thattheir filaments are united inspherical attached colonies and theytaper from base to apex.
The basal vegetative cell of eachfilament becomes transformed intoa heterocyst.
Spirulinasp. Long been valued as a food
source; it is high in protein,and can be cultivated inponds quite easily.
In the US, the popularity ofS irulinais rimaril as a
Filamentous
Akinetes are lacking "health food", being sold instores as a dried powder orin tablet form.
According to cell structure Homocystinae have
cells that areuniform in size.Their cells aremostly vegetative,branched and do not
possess anyheterocyst.
Heterocystinae possesses heterocystand akinetes. Their cells areunbranched and made up of filaments.They are good materials for fertilizingplants because they have thicker cellwalls and possess heterocysts which are
responsible for nitrogen-fixation.
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DIVISION EUGLENOPHYTAHABITAT
Almost all of which are found in
freshwaters puddles, ditches,ponds, streams, lakes and rivers;particularly waters contaminatedby animal pollution or decayingorganic matter.
Most often found in small poolsrich in organic matter. Thepigmented forms, especiallyEuglena, are frequently present insufficient abundance to color the
water.
General characteristics Pigments present:
Chlorophyll a & b with betacarotene only, and contain
at least one xanthophylls.
Thalli organization: Thecells are solitar and never
Flagella of Euglenales areinserted in the base of thereservoir and projectthrough the cytopharynx and
cytosome.
Uniflagellate genera -flagellum projecting forward.
united in colonies.
Reserve Food: Foodreserve consists of
paramylum (an insolublecarbohydrate related tostarch) and fats.
Biflagellate genera - haveboth flagella of equal length,one projecting forward andthe other trailing.
Flagella of Euglenales are ofthe so-called tinsel type inwhich there are delicatehair-like appendages alongthe length of the flagellum.These appendages are calledmastigonemes.
General characteristics Cell Shape: The exterior
portion of the cytoplasm isalways differentiated into aperiplast. The periplast may beso rigid that the cells have afixed shape, or it may be soflexible that the shape of a cellis constantly changing as itswims throu h the water.
Asexual Reproduction Multiplication is by cell division and may take place while cells are
actively motile or after they have come to rest.
Thick walled resting stages (cysts) surrounded by a firm wall are knownfor many genera. Sometimes the cyst is of the same general shape as a
motile cell, but more often it is quite different in shape and eitherspherical or polygonal.
Reproduction - diverse
Vegetativecell
resist antcell(restingstage)
Encystment
Germ ination
Asexual reproduction
usually binaryfission
Sexual reproduction possibly
motile gametes or conjugation tubes
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fresh and marine waters on moist wood and rocks and on the surface of and
within soil.
Epiphytic Form water blooms Cryoflora Form association with fungi
HABITAT
Chloroplasts shape
SpiralSpiralSpiralSpiral----shaped chloroplastsshaped chloroplastsshaped chloroplastsshaped chloroplasts
The cells contain: chlorophyll a and b and -carotenes
Xanthophylls Pyrenoids are present in the
chloroplasts of most Chlorophyta.They are the centers of formationof the enzyme amylose synthetase,which combines glucose moleculesinto starch.
Pigments presentband/ girdle-
shapedchloroplasts
reticulated/ netreticulated/ netreticulated/ netreticulated/ net----likelikelikelike
chloroplastschloroplastschloroplastschloroplasts
Asexualreproduction
cell division (unicellularforms)
fragmentation (colonial andfilamentous types)
production of special
Unicellular (non-motile andmotile)
Colonial (coenobic and non-
coenobic) Filamentous (simple, branched,heterotrichous)
Membranous Siphonous
THALLUS
zoospores, aplanospores andautospores.
Colonial genera reproduce bydaughter-colony formation.
Motile organisms (Colonial) Its slightly ovoidal colonies
may contain thousand of cellsarranged at the periphery ofthe matrix.
The protoplasts of theindividual cells are connectedby delicate protoplasmicextensions.
Sexual reproduction isoogamous.
The enlarged cells within the
colony are called zoospores
Non-motile organismUnicellular (Azoosporic)
fresh, salt water and in soil. The protoplast is composed of a
cuplike chloroplast, which may ormay not contain a pyrenoid.
Asexual reproduction ofunicellular genera is by celldivision preceded by mitosis.
Organized as two semicellsthat are mirror images of eachother; the connecting region isknown as isthmus. Flagellatemotile cells are absent.
Isthmus
Hydrodictyonsp.
water net
The mature colonies are composed oflarge cylindrical cells joined together inpolygonal configurations, the wholecolony being cylindrical. The youngcells are uninucleate.
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Non-motile organism(colonial azoosporic)Pediastrumsp.
Coenobic colonies (flat plates) grow on the bottomof quiet pools and lakes as well as in their planktonand may readily be grown.
Scenedesmussp.
This coenobic alga is ubiquitous. It consists of acolony comprising four or more elongate cells unitedlaterally. have spinelike processes. The uninucleatecells have a parietal chloroplast containing a singlepyrenoid.
Filamentous organisms - zoosporicUlothrixsp.
The cells of each filament are similar to one another exceptthat the basal cell is modified as an attaching structure, theholdfast.
The cells contain partial or complete band-shapedchloroplasts with more than one pyrenoid and areuninucleate.
Oedogoniumsp. It grows frequently as an epiphyte on other algae and
aquatic angiosperms. It may also be attached to stones orfree-floating.
The cells contain segmented, netlike chloroplasts withpyrenoids.
Cladophorasp.
Widespread in both fresh and marinewaters, where they may be free-floating or attached to rocks orvegetation.
Filamentous organisms - azoosporicSpirogyrasp. It often form floating, bright-green, frothy, and/or
slimy masses in small bodies of water in the spring of theyear and are frequently referred to as pond scums.
Masses of the plants are slimy to the touch, because thefilaments are surrounded by pectic sheaths.
It has a spiral arrangement of ribbonlike chloroplasts.
Membranous The plant body of a membranous green algae is composed
of a single layer (monostromatic) or two layers of cells(distromatic).
A membranous plant habit is an expanded sheath.
Coenocytic and TubularThe unit of organization is a centrally vacuolatedtube or siphon. The plant has a complete lack orrare production of cross walls. It is multinucleateand coenocytic in form lacking septa, thecytoplasm is continuous throughout the plant body.
A siphonous plant habit has no septations andcross-walls, but there may be septation because of
separate it from the other structures.
Acetabulariasp.
Known as the mermaids wine goblet or mermaids
parasol, a calcified organism widely distributed insubtropical and tropical waters.
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DIVISION CHAROPHYTAGeneral characteristics
The plant consists of abranching axis on which arisewhorls or smaller branches oflimited growth, often calledleaves.
The lower portions of the axesare anchored to the substratumby branching filaments, therhizoids.
Cell walls contain cellulose andare calcified.
Pigments: chlorophylls a and b,
carotene and xanthophylls.
Reserve food: starch
The rhizoids serve as organs of
vegetative propagation, givingrise to erect green shoots.Branches arise at the nodesamong the leaf base.
Have nodes and internodes,cortication of the axes andleaves, and the occurrence ofspecial cellular sheaths aroundthe sexual organs.
Reproduction Reproduction in the Charophyta is
oogamous and the gametes areproduced in specialized complexstructures usually called antheridiaand oogonia, but sometimesdesignated the globule and nucule,respectively.
The reproductive structures areborne on the leaves.
The mature male reproductive organconsists of chains of colorless cellseach of which produces a singlesperm, surrounded by several typesof sterile accessory cells, the wholestructure is stalked.
The female reproductive organ ofthe Charophyta consists of a fertile
cell, the oogonium proper,surrounded by spirally elongatesterile cells, the tube cells. Theapices of these are delimited toform the five cells of the corona orcrown.
DIVISION XANTHOPHYTAGeneral characteristics
Yellow-green algae
Pigments: chlorophyll a, -carotene, and severalxanthophylls pigments.
Reserved food: Droplets ofoil and granules calledleucosin, or chrysolaminarin
F age ation: T e age aare of unequal length, thelonger tinsel and the shorterwhiplash in organization.
DIVISION BASCILLARIOPHYTAGeneral characteristics
Pigments: chlorophylls a andc, -carotene andfucoxanthin (largelyresponsible for the color ofdiatoms).
Reserved food: oil andchrysolaminarin. Diatoms may be strictly
, ,filamentous.
They are divided into twotypes on the basis ofsymmetry. the pennatediatoms, bilateral symmetry ;and centric diatoms, radialsymmetry.
Cell wall: The wall isimpregnated withpolymerized opaline silica.
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DIVISION PYRROPHYTAGeneral characteristics
Pigments: chlorophylls a and c, -carotene,several xanthophylls (peridinin anddinoxanthin).
Reserved food: Starch accumulates bothwithin the chloroplast and colorlesscytoplasm, and oils may also be stored.
Fla ellation:
One flagellum is elongate, usuallyextending posteriorly with reference tothe direction of motion.
The second flagellum, which emergesfrom the same point as the first, is
ribbon-like and lies in a transverse groovein which it undergoes undulatingmovement.
Both flagella are of the tinsel type.
Causes Red Tide.
DIVISION PHAEOPHYTAGeneral characteristics
Pigments present: fucoxanthinis dominant over chlorophylls aand c, the other xanthophylls
and -carotene.
Reserved food: No starch;laminarin, mannitol, or fat
Flagella: laterally or subapicallybiflagellate. The longer, usuallyanterior, flagellum is of thetinsel type, and the shorter,posterior one is whiplash.
Thallus: FILAMENTOUS, Manyhave considerable complexity of
.
The protoplast is bounded by aprimary wall and middle lamellacomposed of a gummy substance,the alginic acid. Alginic acid hasconsiderable commercialimportance as a stabilizer,emulsifier, and coating forpaper.
s ruc ure, as man es e n e rleaflike, stemlike, and rootlikeorgans, which exhibit obvioushistological differentiation.
Life cycle Three kinds of life cycles:
Isomorphic alternation of generation (Isogeneratae)
Heteromorphic alternation of generation (Heterogeneratae)
Alternation of many-celled diploid generation, only 2Ngeneration (Cyclosporae).
. A simple brown algae commonly growing on
stones and shells or epiphytically on largermarine algae.
It is a branching filamentous plant in whicherect filaments arise from an attachedprostrate branched system.
The mature cells contain band-shaped plastidswith pyrenoidlike bodies.
Filamentous Brown Algae, e.g.Ectocarpus(filaments with plurilocular and unilocular sporangia)
Habitat - Ocean shores, on rocks and larger seaweeds, worldwide
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Diploid
Haploid
Sporophyte>
Meiosis
Fertilization
Diploidzospores
Gametes
n.b. MEIOSIS occurs
in UNILOCULAR
sporangia and
MITOSIS in
PLURILOCULAR
sporangia
Life History of
Ectocarpus -
Isomorphic
Alternation of
GenerationsGametophyte>
Haploid zospores
Mitosis
Laminaria- characteristics
Typical morphology: Holdfast for
attachment
Stipe for support Blade for
photosynthesis and
Reproduction: sexual 2 generations: small
gametophyte, largesporophyte
Dictyota Growth in the blades of
Dictyotais geometric inprecision and may be traced to aprominent, dome-shaped cell.
FucusFlat, dichotomously branched fronds, short stipe,
Conspicuous midrib: simple transport system
Bladders present or absent
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A tropical relative of the Rockweeds - Sargassum
n.b. floats are on separate
branches.
Two species of
Sargassum (S. natans and
S. luitans are free-
floating, and are not
known to reproduce
sexually. Typical of the
Sargasso Sea, and known
as Sargasso Weed or Gulf
Weed.
Economic importance of Brown Algae
Used as emulsifiers and industrials gums
In Europe, kelps and rockweeds were burned for their soda, usedin glazing and glass making, from the 17th Century.
In the early 19th Century, iodine was extracted from kelp ash. Algin, first discovered in the 1880s, is a complex organic
compound used in dozens of different products, includingtoothpaste, ice cream, milk shakes and textiles.
In parts of Europe, kelps and rockweeds are used as manure, andoccasionally as livestock feed.
The Japanese use Laminariaspp. to make Kombu and anotherbrown alga, Undaria, to make Wakame
DIVISION RHODOPHYTAGeneral characteristics
Pigments: chlorophylls a and d (whenpresent) and the carotenoids arelargely concealed by a red pigment,phycoerythrin.
Reserved food: Floridean starch
Thalli organization: unicellular,filamentous, membranous, foliaceous,quite large but not as large as thebrowns; more delicate, more slimyand soft, attached, benthic.
The cellulose cell wall is oftensurrounded by a slimy layer. Othercomponents such as xylan are
present in the walls of some redalgae.
Life History: 3 phases 1. Tetrasporophyte (2n):
produces tetraspores bymeiosis
2. Gametophyte (n): Tetraspores germinate to
form gametophytes, roduce ametes b mitosis
3. Carposporophyte (2n): results from the fusion of
gametes, develops on thefemale gametophyte plant
produces diploid sporescalled carpospores bymitosis (carposporesnew tetrasporophyte plant)
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Porphyra The brown-purple or rose-tinted, Ulva-like
plant bodies of Porphyra grow attached torocks or to larger marine algae.
The fronds may become more than a foot in
length. They are composed of one or two layers of
cells.
The plants are attached to the substratum.
Polysiphonia It is also widely distributed in marine
waters, where it grows bothepiphytically on larger algae andaquatic flowering plants and also onrocks and woodwork.
Peculiarities in the Life Cycle of Polysiphonia
TWO sporophytic and one gametophytic phase
The ogonium has a unique appearance and function, and is
therefore called a CARPOGONIUM Because the male gametes are non-motile, they are known asSPERMATIA
,CARPOSPOROPHYTE, is small, and remains attached to thefemale gametophyte. It produces CARPOSPORES by mitosis
Carpospores germinate into TETRASPOROPHYTES , whichlook like the gametophyte, but produce haploid TETRASPORES
by meiosis.
Life cycle of Polysiphonia
tetraspores