Reproduction in Algae By Dr. Neeraj Kumar Tiwari.pdf

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1. REPRODUCTION IN ALGAE
Dr. Neeraj Kumar Tiwari
Department of Education
Mahatma Gandhi T.T. College Mahwa, Dausa (Raj.)

2. Reproduction in Algae
A)Vegetativereproduction-
B)Asexualreproduction-
C)Sexualreproduction-
A)Vegetativereproduction-
Itisthemostcommonmethodofreproductioninalgae.
Inwhichportions/partoftheplantbodybecomeseparatedofftogive
risetonewindividuals,withoutanyobviouschangesinthe
protoplast.

3. a)CelldivisionorFission:Ex.-Euglena,Chlamydomonas
Commoninunicellularforms
Celldividesmitotically
Formationoftwodaughtercells
b)Fragmentation:Ex.-Spirogyra,Zygnema
Commoninfilamentousforms
Thallusbreaksintosmallfragments
Duetomechanicalpressure
Dissolutionoftransversewalls

4. c) Hormogonia : Ex. -Oscillatoria, Nostoc
Common in blue-green algae
Short multicellular filament –Hormogonia
Under unfavorableconditions
d) Adventitious branches : Ex. -Fucus, Dictyota
Found in larger thalloid forms
Branches detached from thallus

5. e) Tubers : Ex. –Chara
Small outgrowth like structure
Develop on lower nodes
Storage of food material
f) Bulbils : Ex. –Chara
Found in Charophytes
Small roundish bodies
After detachment it germinates
g) AmylumStars: Ex. –Chara
Multicellular Star-shaped bodies
Contains Amylum starch

6. h) Budding : Ex. –Protosiphon
Bud-like structures are formed
Proliferation of vesicles
Separated from parent thallus
B) Asexual reproduction-
Asexual reproduction involves obvious changes
in the protoplast
Reproductive bodies are either naked or provided
with a newly synthesized wall of their own
Asexual reproduction takes place by a variety of
motile or non-motile spores
Asexual spores germinate without fusing and form
new individuals

7. Asexual spores may be differentiated into different categories on the basis of their
structure –
Zoospores : Ex.-Chlamydomonas, Oedogonium
These are pear-shaped , motile , naked structures
with two or more flagella
Synzoospores: Ex.-Vaucheria
Develop inside the zoosporangium
Ovoid, yellow-green, multinucleate and multiflagellatestructure
Also called as compound zoospore
Aplanospores : Ex.-Vaucheria
Develop inside the aplanosporangium
Club-shaped, non-flagellate, thin-walled spore

8. Hypnospores: Ex.-Vaucheria
Develop in unfavourableconditions
Thick-walled, non-motile aplanospores
Tetraspores: Ex.-Polysiphonia(2X)
Develop within tetrasporangium
Aplanospore with haploid nature
Autospores : Ex.-Chlorella
Autospores are replica of the parent cell
Smaller in size

9. Akinetes : Ex.-Cladophora, Pithophora, Nostoc
Develop in unfavourable conditions
Thick-walled, modified vegetative cells
Stored more food material
Exospores :Ex.-Chamaesiphon
Found in blue-green algae
Non-motile spores are produced exogenously
Endospores :Ex.-Dermocarpa
Contents divide successively
Non-motile spores are produced endogenously

10. C) Sexual reproduction :
Fusion of two gametes to form a zygote
i) Isogamy : Ex.-Ulothrix
Fusion between two identical gametes
ii) Anisogamy : Ex.-Chlamydomonas braunii
Fusion between two dissimilar gametes
Morphological
Physiological
iii) Oogamy: Ex.-Oedogonium
Most advanced type
Large non-motile egg fuses with small motile sperm