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					                     What Alga Is?

    Chlorophyll bearing organisms with thylloid
  (having no True roots., stems and leaves ).
      Word Origination
 Algae has about 3000species & 2000 genera
 Algae has world wide distribution from Europe -
  Pacific and Asia.( Arctic, Antarctic,North& South
  America).
                Occurrence & Habitat
         Been recorded from snow, hot springs, tide pools to
                  rocky coasts
          or floating as masses of filaments or
                    water blooms.

 See Weeds are mostly found in Rocky Coasts
 Euglena ,Diatoms & Anabaena found in River & Ditches
 Polycystis & Dinoflagellates found in Moist Places (Tree Trunks
                            History


Early reference found in Chinese Literature mentioned as TsaO
Greeks & Roman literature used words like Phycos & Fucus
 Inhabitants of   Hawaii used it as food known as Limu.
     Classification
• Algae classification is
                         based on following bases.


Pigments
Reserve food products
Flagellation
Cell wall
Cell Structure
            Forms of Algae (W.h.Harvay)
• Red Algae

• Brown Algae

• Green algae

• Diatoms
                            Morphology
Algae are Eukaryotic except Blue Green Algae.

                                      Flagella
Flagella are found in all except Cyanophyta &   Rhodophyta

Three important points
                       Nature
                      Number
                      Position of Flagella in primary
                      Classification of Algae
• Cell Wall
             Made up of two materials
Inner                Water Insoluble

Outer               Pectic substances

Most common material of inner layer is

                    Cellulose
In cell wall of Phaephyta alaginic & Fucinic acid are found whereas
    mucopeptide is present in cell wall of Blue-Green Algae.
In some algae, walls contain definite Pores for Mucilage discharge & connections
    for protoplasmic connections.
          Plastids & Chromatophores
• Double membrane structures are of two types
      Colored         Chromatophores
      Colorless       Leucoplasts
                     Plastids
Leucoplasts                              Chromatophores
Chlorophyll a & b                         Chlorophyll b
                     Pyrenoids




Protinaceous fibrils on or in the Chromatophore surface.
One in Chlamydomonas or many in Oedogonium
Store starch in green algae
Found in all except Cyanophyta
Arise De Novo or by Division of pre-existing cells.
Golgi Bodies                    Mitochondria                     ER


G-Complex here is known as    Are present           Present in Most Algae
        Dictyosomes.

Situated near Chromatophores, Number & size vary.   System of tubules.
Flagella, nucleus.

Exact function not defined    Exact function is     Ribosomes on outer
so far.                       Respiratory related.    Surface

Absent in Cyanophyta.         Absent in Cyanophyta Absent in Cyanophyta.
Vacuoles                      Eye Spots (Stigma)

 One or More Vacuoles.        Orange eye-spot located
 Meant for Osmotic Relation   Consist of Lipid Droplets
  & regulation of Solutes      present irregularly.

                               They are light sensitive
 Two Types                    photoreceptors.
1. Contractile
2. Complex                     It helps in orientation of motile
                               Flagella.
                       Ecology
• The various sorts of algae play significant roles in aquatic
  ecology
• Provide the food base for most marine food chains
• In very high densities (so-called algal blooms) discolor the
  water and out compete, asphyxiate other life forms
• Sea weeds have been recorded at depth of 300m.
• Some are used as human food or harvested for useful
  substances such as agar, carrageenan, or fertilizer
                          Nutrition
Cell                Chlorophyll                   Store light Energy
CO2 + Water (Surrounding Environment)             Sugars

                  Chemical equation
6CO +12H O
   2    2                               C H H 6O +6H O
                                         6   12   6+   2   2




Photoautotrophic
Holozoic
Parasitic
Heterotrophic
                    Reproduction
• Vegetative
• Sexual
• Asexual
                    Vegetative Reproduction
Unicellular Cells     Cell division
Filamentous forms     Fragments forms   Fragmentation
Example
                     Blue Green Algae
                Asexual Reproduction
Special cells types                    Replication of Organism

Asexual Reproduction results in development & maintenance of
                      stable population.

                      Sexual Reproduction
    Sexual reproduction involves
    Union of Cells(Plasmogamy)
    Union of Nuclei(Karyogamy)
                           Uses
Largest source of oxygen producer 83-87% of the total   oxygen
Bio-diesel production .

There are also commercial uses of algae as agar

Some Cosmetics can come from micro algae as well

chemical dyes and coloring agents

Seaweeds are used as fertilisers and even food

Algae are used in wastewater treatment facilities
                  Algae and symbioses
lichens: A fungus is the host, usually with a green alga or a cyanobacterium as its
symbiont
Corals: algae known as zooxanthellae are symbionts with corals. Notable amongst
these is the dinoflagellate Symbiodinium, found in many hard corals.
Sponges: green algae live close to the surface of some sponges, for example,
breadcrumb sponge (Halichondria panacea). The alga is thus protected from
predators; the sponge is provided with oxygen and sugars which can account for 50 to
80% of sponge growth in some species.

				
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posted:9/18/2012
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