Structure of algae.pptx

Algal structure, habit, habitat, size,
reproduction of algae, sexual and asexual methods, cellularity

1. ALAGE R. Nithya, M. Sc., M. Phil., Ph. D, Assistant Professor in Biotechnology, Sri Adi Chunchanagiri Women’s College, Cumbum Theni Dt.

2. INTRODUCTION Algae are simple, chlorophyll bearing plants. Autotrophic organisms. Mostly unicellular, others are aggregation of many similar cells Study of Algae – Algology or Phycology ( Phykos - alga in Greek) Algae varies in Size Habit Habitat Reproduction processes

3. Size Size ranges from microscopic to several metres in length (e.g. Sea weeds)

4. Habitat Abundantly present in sea water, fresh water, on damp soil, plants and animals, rocks, stones, barks trees. Algae are aquatic or terrestrial Most of them are aquatic. Terrestrial forms are live in moist place Aquatic algae may be marine of fresh water forms They are either free living or attached forms

5. Free living - Plankton

6. Algae attached to rocks - Lithophytes

7. Algae attached to plants - Epiphytes

8. Algae attached to animals – epizoophytes

9. Few algae are - Parasites

10. Some live as symbionts with fungi to form - Lichens

11. Cellularity Exist in unicellular forms Multicellular forms Filamentous Membranous Blade like or tubular Unicellular They are single celled algae They may be motile flagellated. Ex. Chlamydomonas They may be non-motile coccoid . Ex. Chlorella   Chlorella

12. Multicellular forms May be in the forms of colonies Ex. Volvox in the form of filaments Ex. Spirogyra Volvox

13. Filamentous Simple or branched filamentous algae Simple filamentous Algae It consist single row of cells Ex. Ulothrix May be free floating or attached Simple filament of blue green algae is called trichomes Ulothrix

14. In some algae The plant body ( thallus ) is differentiated into root, stem and leaf Eg . Sargassum Fucus Laminaria Sargassum Fucus Laminaria

15. Structure of algae The plant body is called thallus It does not differentaiated into root, stem, leaf and true tissues May be prokaryotes or Eukaryotes Prokaryotes All blue green algae are prokaryotes

16. Eukaryotes Cell consist cell wall plasma membrane cytoplasm Nucleus Cytoplasm consists mitochondria Plastids Ribosomes Golgi complex Endoplasmic reticulum

17. Cell wall Cell wall is surrounded by a thin, rigid cell wall Have an outermatrix lying outside the cellwall Outer matrix is flexible & gelatinous like bacterial capsule Nucleus True nucleus is present It has nuclear envelope with pores With in the nucleus Nucleolus, Chromatin, Karyolymph is present.

18. Mitochondria Structure of mitochondria varies greatly Euglenoids have – discoid cristae Green and red algae – lamellar cristae Golden brown, Yellow green, Brown algae, diatoms – tubular cristae

19. Chloroplast In algae chloroplast exist in different shapes Chlamydomonas - cup shaped Ulothrix - gridle shaped Zygnemia - star shaped Spirogyra - spiral shaped

20. CHLOROPLAST It has membrane bound sac called thylakoids Thylakoids carry out the light reaction of photosynthesis These organelles are embedded in the stroma where dark reactions is takes place Also contains one or more spherical bodies called pyrenoids Pyrenoids synthesis and store the starch material

21. Plastids ( Chromatophores ) Contain pigments There are 3 types Chlorophylls Carotenoids Biliproteins or phycobilins Chlorophyll Green pigment Five types of chlorophylls are present Chlorophyll a – found in all classes of algae Chlorophyll b Chlorophyll c Chlorophyll d Chlorophyll e Other types (b, c, d, e) are found in some algae

22. Carotenoids Yellow, orange or red pigment 2 types – carotenes and xanthophylls Carotene – 3 types Carotene a, b and g Xanthophylls – yellow in colour Bili proteins Protein pigments Two types Phycocyanin – blue in colour Phycoerythrin – red in colour These pigmetns are present in chloroplast Flagella Some algae possess flagella Algae are motile

23. Reproduction Occur in three ways Vegetative Asexual Sexual Vegetative Fragmentation Plant body thallus breaks up and each fragmented part grows to form a new thallus

24. Asexual Reproduction Occur by spore formation and binary fission Spore are formed in ordinary vegetative cells or in specialized structure termed sporangia Sporangia produce two types of spores Flagellated motile spore – zoospores Non motile spores – aplanospores

25. Binary fission In some unicellular algae reproduction occur by binary fission

26. Sexual reproduction Occur by egg formation Eggs are formed in unmodified vegetative cells called oogonia Oogonia function as female structure Sperms are produced in male reproductive structure called antheridia In sexual reproduction these gametes fused together to produce diploid zygote

27. THANK YOU