Chlorophyta are a division of green algae that contain about 20,000 species. They are eukaryotic organisms with membrane-bound organelles like chloroplasts containing chlorophyll. Their thalli range from unicellular to multicellular filamentous forms. Reproduction can occur asexually through zoospores or sexually from isogamy to oogamy. They exhibit a variety of life cycles including haplontic and diplohaplontic patterns with alternation of generations. Chlorophyta are an important group of photosynthetic organisms and include many common pond algae.

1. CHLOROPHYTA
ALEN SHAJI
P1914015

2. INTRODUCTION
 About 20,000 species.
 Eukaryotic cell and contain all the membrane bound
organells.
 Thallus is green due to the presence of green pigment
chlorophyll.
 Chlorophyll is contained in chloroplast.
 Pyrenoids embedded in chloroplast.
 Cytoplasm contains vacuoles.
 Motile cell of primitive forms contains eye spot or stigma.
 Reserve carbohydrates are in the form of starch.
 Cell wall invariably contains cellulose.
 Produce motile reproductive bodies generally with two or
four flagella.

3. OCCURENCE
 Most are aquatic but some are subarial.
 Several species of ulvales and siphonales are marine.
 Some strains of chlorella are thermophilic.
 Species of chlamydomonas and some chlorococcales occur
in snow.
 Coloechaete nitellarum is endophytic.
 Cephaleuros is parasitic – cause ‘red rust of tea’.
 Live epizoically on or endozoically within the bodies of
lower animals – chlorella is found in hydra; chlorella
beneath the scales of fish; characium on the antennae of
mosquito.
 Green algae in assosciation with the fungi constitute
lichens.

4. THALLUS ORGANIZATION
1. UNICELLULAR THALLUS
A] MOTILE UNICELLULAR THALLUS
eg; Chlamydomonas

5. B] NON MOTILE UNICELLULAR THALLUS
eg; Chlorococcum

6. 2. COLONIAL THALLUS
A] MOTILE COLONIAL THALLUS
eg; Volvox, Pandorina

7. B] NON MOTILE COLONIAL THALLUS
eg; Pediastrum, Hydrodictyon

8. 3. SIPHONOUS OR COENOCYTIC THALLUS
eg; Characium, Acetabularia

9. 4. MULTICELLULAR FILAMENTOUS THALLUS
A] SIMPLE FILAMENT
eg; Spirogyra, Ulothrix,
Oedogonium

10. B] BRANCHED FILAMENT
eg; Bulbochaete, Chaetophora, Cladophora

11. C] FOLIACEOUS THALLUS
eg; Ulva
D] MASSIVE PARENCHYMA
TOUS THALLUS

12. E] HETEROTRICHOUS FILAMENT
eg; Stigeoclonium, Fritschiella, Coleochaete,
Draparnaldia, Draparnaldiopsis

13. CELL STRUCTURE
 Protoplast is bounded by a thin plasma membrane and
shows an advance over the cyanophyta in the presence of a
definite nucleus, a distinct cytoplasm, one or more
membrane limited chloroplasts, mitochondria,
dictyosomes, endoplasmic reticulum, and frequently a sap
cavity.
 Cell wall is stable.
 Inner layer of cell wall is composed of cellulose which
occurs in the form of microfibrillar units.[excptn; callose in
siphonales]
 Outer layer of cell wall is made of pectose.
 In spirogyra; outermost portion of pectose changes into
pectin and it dissolves in water to form gelatinous sheath
which is slimy and it envelops the entire filament.

14.  In ulothrix, oedogonium, cladophora; an insoluble
substance impregnates into the external portion of the
pectose layer and prevents dissolving away of pectose.
 In chlorogonium, haematococcus; cell wall is composed of
hemicellulose.
 Cell wall of some marine caulerpales [old name
siphonales] are impregnated with lime.
 In desmids; deposition of iron compounds has been
reported on cell walls.
 Protoplast containing plasma membrane contains three
layers; middle lipid layer is sandwiched between the two
protein layers.
 Vacuoles are present; function as osmoregulatory
organelles, absent in motile forms of volvocales and non
motile forms of chlorococcales.
 Big central vacoule is traversed by a number of cytoplasmic
strands that shoot out from the lining layer of cytoplasm
refered to as the primordial utricle.

15.  Large central vacoule is boundedby a definite plasma
membrane known as the tonoplast.
 Plasmodesmata are present in volvox, eudorina.
 Mitochondria, golgi bodies [dictyosomes], ribosomes,
endoplasmic reticulum, chloroplasts are present.

16. CHLOROPLAST
 Pigment containg bodies in green algae and charophyta are
called chloroplasts and but in all other algal divisions except
euglenophyta, they are referred to as chromatophores.
 Plastids which contain both chlorophyll a and chlorophyll b are
usually termed as chloroplasts.
 Plastids which contain chlorophyll a but not chlorophyll b and
have carotenoids in excess over chlorophyll are known as
chromatophores.
 Green pigments- chlorophyll a and chlorophyll b.
 Yellow pigments- carotene and xanthophyll.
 Green colouration of members of chlorophyta is due to the
presence of excess of chlorophyll in the chloroplasts.
 Beta carotene is commonly found in green algae.

17. • Sacsdb
A] large cup shaped chloroplasts- volvacales.
B] single; collar shaped chloroplasts- ulothrix.
C] discoid chloroplast- siphonales.
D] parietal, girdle shaped with incised margins and more or less
reticulate- draparnaldiopsis.
E] band like chloroplast- debarya.
F] parietal ribbon shaped, spirally wound chloroplast- conjugales.
G] two parietal plates with a nucleus in between a pair of axial
stellate bodies- conjugales.
H] an axial plate- conjugales.

18.  Complex structure among
eukaryotic algae.
 Double membrane envelope
limits the chloroplasts.
 Matrix within is often full of
lamellar structure and is
thus greately reduced.
 Number of thylakoids in
the stack varies within
a wide range.
 Usually, 2-20 discs in a band
or stack.
 In nitella; 40-100 thylakoids
in a single stack.

19.  Thylakoids in the stacks assosciate and dissociate in various
ways giving a grana like appearance.
 Stacks are well defined with discs closely appressed
together.
 Some of the bands extend for a considerable distance.
 Discs in the stacks may often shift from one stack to
another.

20.  In some green algae; the discs appear to be randomly
arranged with little suggestion of regular stacks.
 Discs come together and separate in an irregular manner.
 Chloroplast matrix contains starch grains besides the
ribosomes and osmiophilic globules.
 In some green algae; the pyrenoid is a region of dense
matrix material in the chloroplast.
 Pyrenoids contains fibrils which are tight packed.
 In spirogyra and cosmarium lundelii; pyrenoid is
transversed by single discs which may be continous with
the chloroplast bands.
 In some green algae; pyrenoid lacs discs.
 Pyrenoid has around it a sheath of starch grains which
seperates it from the chloroplast matrix.

21.  CHLOROPLAST OF CHLOROPHYTA

22.  FLAGELLA OF CHLOROPHYTA

23.  Fine protoplasmic whiplike threads called flagella helps in
locomotion.
 Usually there are two or four flagella of equal lengths
[isokontic].
 Inserted at the anterior or apical end of the motile cells.
 In oedogoniales; motile cells have a ring of flagella.
 Flagella in green algae have a smooth surface and are called
whiplas or acronematic.
 Flagellum is an extremely fine, hyaline emergence of the
cytoplasm.
 Usually there is a single granule at the base of each flagellum
known as the blepharoplast or basal body.
 Each flagellum consists of a thin axial filament of axoneme
surrounded by a cytoplasmic membrane or sheath which is an
extension of the cell or plasma membrane.
 Naked portion of the axoneme is called the end piece.
 Axoneme constists of 11 fibrils; two are in centre and known as
the axial or central fibrils.

24. SIMILARITIES OF THE CELL STRUCTURE OF A GREEN
ALGAE WITH HIGHER PLANTS
1] Presence of chlorophyll a and chlorophyll b as the
principal pigments.
2] Accessory pigments [xanthophylls and carotenes]
are the same in both.
3] Starch as the principal food reserve.
4] Components of cell such as the cytoplasm, nucleus,
cell membranes, and chloroplasts have basically the
same structure as those of the higher plants.

25. VEGETATIVE REPRODUCTION
1] CELL DIVISION
 Also called as fission.
 In unicellular forms; it is a method of reproduction.
 In multicellular forms; it leads to growth.
 Division of the cell is preceeded by the division of the
nucleus which is mitotic and it is followed by the cleavage
of the cytoplasm which begins by a median constriction at
the periphery.

26. 2] FRAGMENTATION
 Breaking up of multicellular
Filamentous thallus into one or
many celled segments of living
Cells.
 Due to the formation of
mitospores or gametes or
external forces in certain parts
of the filament followed by the
breaking up of empty cells.

27. 3] AKINETES
 They are one celled specially modified resting
vegetative structures.
 Akinetes enable plant to tide over unfavourable
conditions.
 On favourable conditions; each
akinete may germinate directly
to a new
individual.

28. ASEXUAL REPRODUCTION
1] ZOOSPORE FORMATION
 Developed in zoosporangia.
 Zoospore is tiny, naked mass
of protoplast containing a single
Nucleus, an eye spot and one or
more chloroplasts.
 Flagella are isokont.
 Inserted at the anterior end.
 Function as locomotory
Organs.

29. STRUCTURE OF ZOOSPORE

30.  On favourable conditions develops into a new plant
resembling the parent.

31. 2] APLANOSPORE FORMATION
 Non motile asexual spores- aplanospores.
 Aplanospore identical to parent cell- autospores.
 Thick walled apalnospores- hypnospores.

32. SEXUAL REPRODUCTION
1] ISOGAMY

33. ISOGAMOUS SEXUAL REPRODUCTION IN
HETEROTHALLIC SPECIES OF CHLAMYDOMONAS

34. 2] ANISOGAMY

35. 3] OOGAMY

36. GERMINATION OF ZYGOSPORE
 Resting stage- zygospores.
 Zygotic meiosis.
 Meiospores.
 Incipient or primitive sporophyte.
 Intermediate meiosis.
 Diploid filament or sporophyte.

37. ALTERNATION OF GENERATION
1] HAPLONTIC LIFE CYCLE OF SPIROGYRA

38. 2] HAPLONTIC LIFE CYCLE OF ULOTHRIX

39. 3] ISOMORPHIC OR HOMOLOGOUS
DIPLOHAPLONTIC LIFE CYCLE IN CLADOPHORA

40. CLASSIFICATION
• There are four classes in the chlorophyta;
1] PRASINOPHYCEAE
2] CHAROPHYCEAE
3] ULVOPHYCEAE
4] CHLOROPHYCEAE

41. PRASINOPHYCE
• Primitive green algae.
• Some of which gave rise to the other classes in the
chlorophyta.
• Scaly or naked flagellates with interzonal spindles that are
persistant during cytokinesis.
CHAROPHYCEAE
• Two flagella attached in a lateral position in the cell.
• Scales common outside of motile cells.
• Motile cells asymmetrical.
• Eyespots usually not present.
• Predominantly freshwater.
• Sexual reproduction involves the formation of a dormant
zygote.
• Meiosis occurs when the zygote germinates.

42. ULVOPHYCEAE
• Flagella attached at anterior end of cell.
• Motile cells have near radial symmetry externally.
• Eyespots common.
• Predominantly marine.
• No dormant zygotes.
• Alternation of generations common.
CHLOROPHYCEAE
• Flagella attached at anterior end of cell.
• Eyespots common.
• Predominantly freshwater.
• Zygote undergoes a dormant period.
• Meiosis occurs when the zygote germinates.

43. TETRASPORINE LINE OF DEVELOPMENT OF THALLUS
IN GREEN ALGAE

44. SALIENT FEATURES
 They are grass green in colour owing to the
preponderance of chlorophyll a and chlorophyll b
over carotene and xanthophyll.
 Pigments are located in the green plastids known as
chloroplasts.
 Reserve carbohydrate food is stored as starch.
 Chloroplast normally contain the pyrenoids.
 Cell has a well defined nucleus and in the higher
forms a central sap cavity in addition.
 Majority produce motile reproductive cells.
 Flagella are isokontic and inserted at the anterior
end.

45.  Sexual reproduction ranges from isogamy to
oogamy.
 Sex organs are always unicellular.
 Zygote generally is the only diploid structure in the
life cycle.
 Plant body is unicellular or multicellular.

46. REFERENCES
 Lee RE, PHYCOLOGY, Cambridge University Press.

47. THANK YOU GOD