Spirogyra is a genus of filamentous green algae that is commonly found in freshwater habitats around the world. It has a fiber-like structure called a thallus that is made of individual tubular cells arranged end to end. Each cell contains chloroplasts and performs photosynthesis. Spirogyra reproduces both asexually through fragmentation of filaments and sexually through the conjugation of filaments to form zygospores. During conjugation, specialized structures called papillae form on adjacent cells and allow the transfer of cytoplasm between them, resulting in fertilization and the formation of a zygote. The zygote then develops a thick protective coating and can remain dormant for

1. Spirogyra
(Apiyrri[giyri)

2. vg)<krN
• sZ(OT - vnAp(t
• up sZ(OT - ap&Op)
• (vBig - kli[ri[fiyTi
• Up(vBig - kli[ri[fiys)
• gi[#i - z)³n)m)T[Ãs
• k&L - z)³n)m)T[s)
• upk&L - Apiyri[giyr)D)
• pÔt) - Apiyrri[giyri

3. (nvisAYin
• 289 Species found around the world
• 94 species reported from India
• Occurs on surface of fresh water places – rivers, ponds, lakes, water
falls etc
• Thallus is fiber like structure
• Possess viscous liquid on surface, hence called “Pond silk”
• Presence of O2 helps thallus to float

5. s&kiy rcni
• Multicelluar, unbranched, tubular in shape, 1 mm in Ø.
• Thallus ends are similar, no differentiation of front and end
• Some sp. Possess Holdfast {Ayi(pt ki[P}
• Physiologically unicellular – each cell carries its own function
Cell Structure:-
• Cell wall – bilayered, absence of pits or ornamentation
• Outer:- Pectin, Pecto Pectin helps become slimy, provides protection
from pest, insects or degradation
• Inner:- single microfibril
• Inter cellular:- tricellular wall +nt, cellulose-pectose-cellulosepossess
middle lamella, some possess single layer, disc like structure, Colligate
helps to develop H shaped disc

6. Jvrs
• Possess Cytoplasm, Nucleus, Chloroplast, Golgi complex, ER,
Mitochondria, microbodies & large Vacuole
• Outer: - cytoplast near cell wall
• Inner:- Large Vacuole +nt around nucleus, Single microfibril joins
both cytoplast
• Nucleus:- 1-16, spirally arranged, anticlock wise, 4-12 thylakoids per
chloroplast, microbodies stores starch and protein.
• Growth:- All cell except holdfast helps

7. ki[P(vBijn
• Nucleus at first divides by mitosis, moves at ends, central wall develops,
cellulose deposition helps wall formation
• Reproduction:-
• Vegetative:-
• i) Fragmentation – breaking of thallus by insects, fishes etc/ wall
breakdown by temp, acidic water/ cell wall degradation/ H disc seperation
• ii) Asexual – Aplanospore {aclb)ÔN&}
• Some sp. Shows this type, motile spores absent, cytoplast gets dehydrated
and becomes jelly, during favorable conditions germinates.

9. Sexual Reproduction
• Male and female thallus are present, monoscious or dioscious,
produces spores. Fusion may be 2 types:-
• 1. Scalariform (Ladder type) Conjugation – si[pinvt` s>y&³mn
• 2. Lateral Conjugation – piÅv)< s>y&³mn

10. 1. Scalariform (Ladder type) Conjugation –
si[pinvt` s>y&³mn
• 1. Maturation Phase – p(rp±v avAYi
• During winter or summer, Male/ female Thalli arrange side by side,
cytoplasm gets concentrated, Papili emerge from the cells, both papili fuse,
possess catalase & cellulose, develops bridge.
• 2. Gametic Union Phase - jºy&ai[n) s>(mln avAYi
• Concentrated Cytoplasm develops like gamate, transfers gamate to the other,
via the papili bridge, forms zygote, nucleus 2n, male cell becomes empty.
• 3. Zygospore Contraction Phase – y&³mb)ÔN&ni) s>ki[cn avAYi
• Dehydrated zygote becomes globular, initially green turns reddish, chloroplast
degrades, starch and oil droplets +nt, turns transparent after maturation, 3
layered, outer – pectin, cellulose, Middle – yellowish, possess spyroline &
inner – cellulosic.

12. 2. Lateral Conjugation – piÅv)< s>y&³mn
• Nearby cells acts as Male and female thalli, develops papili, 2 types
observed:-
• 1. Indirect Lateral Conjugation – pri[x piÅv)<y
• 2. Direct Lateral Conjugation – pRyx piÅv)<y
• One cell becomes large acts as Female Gamete, smaller cell develops
papili on adjacent wall and transfers its cytoplasm to adjoining cells,
Zygote forms

13. Maturation & Germination of Zygospores
• Zygote (2n), liberated by fragmentation, resting 4-7
months, after proper environment Condition,
becomes active, meiosis occurs, 3 degenerate one
remain active, breaks open outer membrane, absorb
water, germination tube, nucleus divides, 2 cells
formed, one develops holdfast cell, other continue to
divide and develops thallus.

15. Parthenogenesis – as>yi[g) jnn
• Some times the gamets directly develops Zygote.
• Without fusion of male and female gamets

20. Economic Importance of Algae
• Part of Food Chain
• As Food
• As Fooder
• In Agriculture
• Origin of Petroleum produts
• Limestone formation
• In Sewage Treatment Plants
• Fish Culture
• Recreational purposes
• Space travel
• Water supplies
• Medicine – Goiter, Stomach disorder, Antibiotics, Blood coagulant, Vermifuge etc
• In Industry – Agar, Alginic acid, Kelp industry, Diatomite, Carrageenin, Iodine, Glue