Algae classification

MICROBIOLOGY- ALGAE CLASSIFICATION

1. Dr. P. Suganya Assistant Professor Department of Biotechnology Sri Kaliswari College (Autonomous) Sivakasi ALGAE CLASSIFICATION

2. Linnaeus  in 1753 was first to introduced the term algae (Latin-  seaweeds ) meaning, the  Hepaticeae . The algae (singular: alga) many of which are are   unicellular. Algae are  ubiquitous,  most of algae lives in aquatic environment but many also thrive a terrestrial and a subterranean alga. Algae contains  chlorophyll  and are  photosynthetic . algae are of great general interest to all biologist because single algal cells are complete organism capable of photosynthesis and the synthesis of a multitude of other compounds which constitutes the cell. The branch that deals with the study of algae are known as as   phycology. Algae chlorophyll bearing  thalloid . INTRODUCTION

3. Algae are present everywhere in distribution. They occur in great abundance in oceans, seas, ponds, fresh water, steams and Salt Lake. Many are found in soil of dam, rocks, stones, and bark of tree and on other animals and plants surface. Small aquatic forms make a large of the free floating microscopic life in water, called  plankton . Phytoplankton  is made up of plants i.e. algal forms. Zooplankton  is composed of animal organisms. Some Species of algae grow on the snow and ice of polar region and mountain peaks. Some, algae grow in hot springes at temperature has high as 55°C. Some are  Endophytice .  They are not free living but live in other organisms such algae are widespread in protozoa, molluscus , sponges and corals. OCCURRENCE

4. Morphology Algae have a wide range of size and shapes. Algae that occur as unicellular and they are spherical, rod-shaped, club-shaped, or spindle shaped. Many are multicellular and have understandable form, shape and various complexity. Algal cells are  eukaryotic . In most of the algal species cell wall is very rigid and thin. Cell wall of diatoms are contain  silica  which makes them thick and rigid. The motile algae have flexible cell membrane called  Periplasts . eg .  Spirulina . Algae contains a discrete nucleus. Chlorophyll and other pigments are found in membrane bound organelles known as  Chloroplast . Within the plastid matrix or stroma are found flattened membranes vesicles called  Thylakoid . CHARACTERISTICS

5. Algal pigments There are three kinds of photosynthetic pigments are present in algae: chlorophyll carotenoid biloproteins or phycobilins

6. Chlorophyll There are five chlorophylls:  A, B, C, D  and Chlorophyll A  is present in all algae. Chlorophyll B  – Euglenophycophyta , Cholorophycophyta . Chlorophyll C–   Xanthophycophyta , Bacillariophycophyta , Chrysophycophyta , Cryptophycophyta . Chlorophyll D  – Rhodophycophyta Chlorophyll E  – Xanthophycophyta .

7. Carotenoids There are two kinds of carotenoids: Carotenes –  linear, unsaturated hydrocarbon. Xanthophyll  – oxygenated derivatives. Biloproteins or phycobilins It is water soluble pigments. Present in  Rhodophycophyta . Two types of phycobilins – P hycocyanin ,  Phycoerythrin

8. The are three main groups of algae being: Green algae Red algae Brown algae. They are classified on the basis of following characteristics: Primary photosynthetic pigments. Storage product . Cell wall composition. Type and location of flagella . Classification of alage

9. Habitat –  Freshwater, Marine and terrestrial. Photosynthetic pigments-  Chlorophyll A and B carotenoid. Cell wall components-  Cellulose. Storage food-  Starch (stored inside the plastids). Flagella-  Two flagella per cell. Asexual reproduction-  reproduce vegetatively by fermentation or by formation of mitospores . Sexual reproduction-  reproduction is of Isogamous , Anisogamous , Oogamous . Example-   Chlamydomonas , Volvox , ulothrix , chara , ulva (sea lettuce ). Example-   Chlamydomonas , Volvox , ulothrix , chara , ulva (sea lettuce). Green algae – Chlorophyceae

10. Habitat-  Marine and freshwater. Photosynthetic pigment-  Chlorophyll A and D, carotenoids and phycobilins . Commonly called red alage because of presence of red pigment  – phycoerythrin . Cell wall components-  Cellulose Stored food-  Floridian starch (alpha -1,4 glucon ) stored in cytosol. Flagella-  Absent. Asexual reproduction-  By fragmentation or by non-motile mitospores . Sexual reproduction-  Oogamous and gametes are non- motile. Example  – Polysiphoria , Gracilaria and Gelidium . Red algae – Rhodophyceae

11. Habitat-  marine and freshwater. Photosynthetic pigment-  chlorophyll A and C, carotenoids and phycobilins . Shades of brown depends on  xanthophyll pigment, fucoxanthin ,  present. Cell wall components-  cellulose and alginic acid. Cellulose is covered by a gelatinous coating of  Algin . Stored food-  Laminarin , mannitol Flagella-  2, unequal, lateral. Asexual reproduction-  by fragmentation or by motile zoospores. Sexual reproduction-  is isogamous , anisogamous , Oogamous . Example  – Ectocarpus , Laminaria , fucus . Brown algae – Phaeophyceae

12. Algae as primary producers-  algae provides the base or beginning of most aquatic animals or organisms because of their photosynthetic activities so it is also known as  primary   producers  of organic matter. Commercial products from algae-  many products are derived from algal cell wall for economic value. Three of these are:  Agar   Alginic Acid , and  Carrageenan , are produced from the walls of algae. Carrageenan  is produced from the walls of several red algae. Species of  Chondrus ,  Gigartina  are mostly used. Agar is well known as a solidifying agent in the preparation of microbiological media. It is obtained from red algae. Species of  Gelidium  and  Gracilaria  are extensively used. Alginic acid  and its salts are obtained from the wall for brown algae. Species of brown algae producing this compound include-   Macrocystis ,  Laminaria ,  Fucus . Algae as food-  many species of algae are (mostly red and brown algae) are used as food in the far east. Red algae one of the most important is  Porphyra :  it is used as food in Japan where it is called Other red algae such as  Chondrus , Nemalion   are locally collected and prepared. Economic importance of algae

13. https://www.biologydiscussion.com/algae/algae-definition-characteristics-and-structure-with diagram/46727 References