handouts on algae

7/29/2019 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

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