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1. ALGAE Bs Biology (E) 2 nd Semester Botany Department.

2. Introduction General Characteristics features Habit & Habitat Organization of Thallus Form & Size of Algae Pigment Constitution of Algae Reproduction of Algae Classification of Algae Economic Importance of Algae Conclusion References SYNOPSIS :-

3. Algae are a diverse group of aquatic organisms that have the ability to conduct photosynthesis. Certain algae are familiar to most people; for instance, seaweeds (such as kelp or phytoplankton), pond scum or the algal blooms in lakes. INTRODUCTION:-

4. Algae are photosynthetic organisms. They can be either unicellular or multicellular . Algae lack a well-defined body, so structures like roots, stems, or leaves are absent. Algae are found where there is adequate moisture. Reproduction in algae occurs in both asexual and sexual forms. Asexual reproduction occurs by spore formation. Algae are free-living, although some can form a symbiotic relationship. General Characteristics Features:-

5. Habit & Habitat 1. Aerial & Terrestrial Algae 2. Aquatic Algae Fresh Water Marine Water 3. Algae of Unusual Habitats Snow Algae Thermal Algae Halophytic Algae Lithophytic Algae Epiphytic Algae Aerophytic Algae Symbiotic Algae Parasitic Algae Epizoic Algae Endozoic Algae

6. Organization of Thallus Palmelloid Motile Dendroid Coccoid Filamentous Heterotrichous Siphonaceous .

7. Form & Size of Algae Algae have a great range of shapes and sizes, from spherical cells with 0.5 µm diameter to 60 m long multicellular thalli . There are about 72,500 validly described species of algae ; they live in the top 300 m of marine and inland waters, and on land.

8. Pigment Constitution of Algae:- Chlorophylls :- Chlorophyll a – present in all higher plants and algae. Chlorophyll b – present in all higher plants and green algae. Chlorophyll c – diatoms and brown algae. Chlorophyll d – red algae. Phycobillins :- Phycocynin - Blue in Colour . Phycoerythrin - Red in Colour . Carotenes:- α- carotene – higher plants and most algae. β- carotene – most plants & some algae. Xanthophylls:- Luteol Fucoxanthol Violaxanthol .

9. Reproduction in Algae:- Vegetative Repro duction Asexual Reproduction Sexual Reproduction

10. Vegetative Reproduction Fragmentation Fission Tubers Adventitious Branches Hormogonia Budding

11. Fragmentation:- The filamentous thallus breaks into fragments, and each fragment is capable of forming new thallus . The common examples are Ulothrix , Spirogyra , Oedogoniwn , Zygnema , Oscillatoria etc.

12. Fission:- Fission is common in desmids, diatoms and other unicellular algae. The cell divides mitotically into two cells are separated by septum formation .

13. Tubers:- Tubers are spherical or globular bodies formed on lower nodes and rhizoids in Chara . They are formed due to storage of food . On detachment of Parent Plant these develop into new plant.

14. Adventitious Branches:- In some cases, certain adventitious branches are produced which break off from the parent body and develop into new plants . Common examples are Chara and Dictyota .

15. Hormogonia : - In blue green algae like Nostoc,Cylindrosperm -um , the main filament breaks into small fragments of varying length called hormogonia . The hormogonia may be formed at the place of heterocyst in the filaments.

16. Budding:- In Protosiphon budding takes place due to proliferation of vesicles . The buds detach to make new thalli .

17. Asexual Reproduction:- Formation from protoplast. Multiply directly without fusion . By varieties of motile or non mobile spores. Spores can be of different types: 1.Zoospores 2.Aplanospores 3.Akinetes 4.Hypnospores 5.Tetra spores 6.Auto spores:

18. 1. Zoospores:- Motile spores , naked , 2 or many flagella. Formed in zoosporangium. Can be haploid or diploid. After release from parent body germinate to new plant. E.g ; Chlamydomonas , Oedogonium , Vaucheria,Chladophorae etc.

19. 2. Aplanospores :- Non motile spores. Flagella absent. Mostly terrestrial but few aquatic. Ulothrix,Microspora . With distinct wall. Eg. Chlamydomonas , zygnema , Vaucheria .

20. 3. Akinetes :- Secrete thick wall in unfavouable condition. These spores germinate in unfavourable condition. e,g ; Pediastrum,Sphaerella . In Chlamydomonas nivalis , hypnospores are red in colour due to deposition of hematochrome . Colour of snow is red in Alpine and Arctic region due to presence of Chlamydomonas nivalis   hypnospores .

21. 4. Hypnospores :- Secrete thick wall in unfavouable condition. These spores germinate in unfavourable condition. e,g ; Pediastrum,Sphaerella . In Chlamydomonas nivalis , hypnospores are red in colour due to deposition of hematochrome . Colour of snow is red in Alpine and Arctic region due to presence of Chlamydomonas nivalis .

22. 5. Tetra spores:- Tetra spores are non-motile spores formed in some members of Rhodophyceae and Phaeophyceae . In Polysiphonia , tetra spores are formed in tetra sporangia by reduction division on special tetrasporophytic plants.

23. 6. Auto spores:- Non- motile,haploid spores. Formed on diploid plants( polysiphonia ). Formed in tetrasporangium after meiosis. Germinate  haploid plant.

24. Sexual Reproduction:- Isogamy Anisogamy Oogamy Hologamy Autogamy

25. 1 . Isogamy :- In isogamous reproduction the fusing gametes are morphologically similar . These gametes are physiologically different due to different hormones . e.g ., Chlamydomonas , Ulothrix , Spirogyra and Zygnema .

26. 2. Anisogamy :- In anisogamy the fusing gametes are morphologically as well as physiologically different. These are formed in different gametangia . The microgametes /male gametes are smaller, active and formed in large number . The macrogametes /female gametes are larger, less active and formed in relatively smaller number e.g ., Chlamydomonas .

27. 3.Oogamy:- It is the most advanced type of sexual reproduction . The male gametes or microgametes are formed in antheridia . The female gamete is large, usually one and formed in female structure Oogonium . During fertilization the male gametes reach Oogonium to fertilize egg and a diploid zygote is formed. e.g., Chlamydomonas .

28. The unicellular thallus of opposite strains (-) and (+) behaves as gametes directly. The thalli fuse to make diploid zygote. e.g., Chlamydomonas . A. Hologamy :- B. Autogamy :- Autogamy two gametes of same mother cell fuse to form diploid zygote. Since both gametes are formed by same cell there is no genetic recombination. e.g., diatoms.

29. Classification of Algae:- Fritsch (1935, 1945) in his book “ The Structure and Reproduction of the Algae” proposed a system of classification of algae. He treated algae giving rank of division and divided it into 11 classes. His classification of algae is mainly based upon characters of pigments, flagella and reserve food material.

30. Classification of Algae:- Class 1. Chlorophyceae (= Isokontae ) Class 2. Xanthophyceae (= Heterokontae ) Class 3. Chrysophyceae Class 4. Bacillariophyceae (diatoms) Class 5. Cryptophyceae Class 6. Dinophyceae Class 7. Chloromonadineae Class 8. Eugleninae Class 9. Phaeophyceae Class 10. Rhodophyceae Class 11. Myxophyceae (= Cyanophyceae )

31. Class Pigments Stored Food Cell Wall Chlorophyceae Chlorophyll a, b; carotenoids Starch Cellulose Xanthophyceae Chlorophyll e,xanthophyll Fat Not specified Chrysophyceae Chlorophyll;phycocyanin Oil,leuosin Two overlaping halves Bacillariophyceae Chlorophyll c;diatomin Oil Silica Cryptophyceae Red,green,blue,olive green . Not specified Not specified Dinophyceae Dark yellow/brown/red. Oil, Starch Not specified Chloromonadine-ae Xanthophyll,bright or olive green Fatty compounds Not specified Eugleninae Chlorophyll Not specified Absent,naked cell Phaeophyceae Fucoxanthin Laminarin,mannitol Not specified Rhodophyceae Phycoerythrin , Chlorophyll d. Floridian, Starch Not specified Myxophyceae Phycocyanin ; Chlorophyll Myxophycean starch,protein Prokaryotic no true nucleus

32. Class Habitat Reproduction Examples Chlorophyceae Freshwater Iso,aniso,oo ( gam-ous ) Spirogyra Xanthophyceae Not specified Fission Vaucheria Chrysophyceae Fresh /marine Not specified Chrysosphaera Bacillariophyceae Fresh /marine Non - motile Navicula Cryptophyceae Fresh/marine Not specified Cryptomonas Dinophyceae Fresh/marine Not specified Peridinum Chloromonadineae Not specified Longitudinal division Vacuolaria Eugleninae Freshwater Not specified Euglena Phaeophyceae Marine Biciliated zoospores Fucus Rhodophyceae Marine Oogamous Polysiphonia Myxophyceae Fresh/marine No sexual reproduction Nostoc

33. ECONOMIC IMPORTANCE OF ALGAE:- Algae as Food Algae as fodder for cattle Utilization of Algae as Fertilizers Utilization of Algae in water Purification Utilization of Algae in Medicine & Antibiotic Use of Algae in Industries Algae in Sewage Disposal Algae in Land Reclamation Algae In Biological Research

34. Conclusion:- According to some scientists , algae produce half of the earth's oxygen. They are a source of crude oil.These algal biofuels could well be a replacement for the fossil fuels. Algae also play an effective role in keeping the atmospheric carbon dioxide. The food industry also uses some algae. Agar is obtained from Gelidium and Gracilaria and is making ice-creams and jellies . The other food supplements that are algae and which are widely used are Chlorella  and  Spirulina .

35. REFERENCES:-

36. THANK YOU.