Division: Chlorophyta




Дата канвертавання27.04.2016
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Lab (3)

Eukaryotic Algae

Division: Chlorophyta

Order: Ulotrichales

Family: Ulotrichaceae

Genus: Ulothrix

Order: Zygnematales (Conjugales)

Family: Zygnemataceae

Genus: Zygnema

Spirogyra


  • Ulothrix: The plant body is consisting of unbranched filament.

  • The filaments appear slender thread like & may be up to 0.04mm in diameter.

  • Except for basal cell all cells of filament are similar in structure.

  • The basal cell (hold fast) is slightly elongated, colorless without chloroplast & through it the filament remains attached to object.

  • The cell usually cylindrical sometime slightly swollen in meddle

  • Sexual reproduction Isogamous


Ulothrix



Ulothrix


Spirogyra: pond scum or pond silk

  • Spiral chloroplast.

  • Vegetative reproduction: Fragmentation.

  • Asexual reproduction: nonfound.

  • Sexual reproduction: by conjugation.

  • Conjugation are two type:

  1. Scalariform conjugation.

  2. Lateral conjugation.



Spirogyra filament



Scalariform conjugation

Lateral conjugation

Zygnema


  • The plant body is a slender unbranched filament composed of series of cylindrical cells.

  • Vegetative reproduction: Fragmentation.

  • Asexual reproduction: Akinete.

  • Sexual reproduction: Isogamous type by conjugation method:

  1. Scalariform conjugation

  2. Lateral conjugation



Zygnema band

Zygnema conjugation


Each Ulothrix cell can undergo division. During sexual reproduction, the cells produce biflagellate isogametes that are released from an opening in the cell wall. Pairs of gametes fuse and form quadri- flagellate zygotes that develop into thick-walled resting cells. The resting cells remain protected in the substrate until the water temperatures become cool enough for germination.



 

During asexual reproduction, scaled quadriflagellate zoospores attach to a suitable substrate and grow quickly into new clonal populations. The zoospores can also survive for long periods of time in the plankton and can travel long distances.









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