ALGAE- STRUCTURE AND CLASSIFICATIONPRESENTED BY:- RAJPAL CHOUDHARYREG. NO.- 161103004M.Sc. BIOTECHNOLOGY 1ST YEAR

INTRODUCTION

• The general term "algae" includes prokaryotic organisms — cyanobacteria, also known as blue-green algae — as well as eukaryotic organisms (all other algal species).

• Algae are a diverse group of aquatic organisms that have the ability to conduct photosynthesis.

• Algae are found in a range of aquatic habitats, both freshwater and saltwater.• Algae are also able to survive on land. Some places where they grow are tree

trunks and animal fur.

STRUCTURE

• They also occur in a variety of forms and sizes. They can exist as single and microscopic cells, they can be macroscopic and multicellular.

• Algal body, also known as thallus, lack true roots, stems and leaves, and a vascular system to circulate water and nutrients throughout their bodies.

• It is broadly divided into two main categories:-a) Unicellular b) Multicellular

UNCELLULARa) Non motile:- A single non-motile

cell carrying out all essential functions of life. Flagella is absent. E.g.- Chlorella

b) Motile:- A single cell with flagella for locomotion.

E.g.- Chlamydomonas Chlorella

MULTICELLULARColony is formed by aggregation of individual cells.Non motile colony:- Individual cell in the colony lacks flagella.E.g.- Pediastrum

Pediastrum

Motile colony:- Individual cells possess flagella.E.g.- Volvox

Volvox

Amorphous colony:- Numerous non motile cells are embedded in a common mucilaginous matrix.E.g.- Tetraspora

Tetraspora

Dendroid forms:- The thallus appears as tree like under microscope.E.g.- Dinobryon

Dinobryon

Filamentous:- Cells arranged one upon the other in a definite sequence forming filament. Filament may be branched or unbranched.E.g.- Spirogyra, Cladophora

Cladophora

Heterotrichous form:- Presence of more than one type of filament.E.g.-Draparnaldiopsis

Draparnaldiopsis

Siphonous form:- Elongated thallus without septation.MultinucleateE.g.- Vaucheria

Vaucheria

Parenchymatous forms:- Cell division and associated septation leads to the formation of a parenchymatous body.E.g.- Chara

Chara

CLASSIFICATION

•Fritsch’s Classification of Algae: • F.E. Fritsch (1935, 1945) in his book “The Structure and

Reproduction of the Algae” proposed a system of classification of algae. He divided it into 11 classes. His classification of algae is mainly based upon characters of pigments, flagella and reserve food material.

• Eleven classes proposed by Fritsch are as follows: • 1. Chlorophyceae • 2. Xanthophyceae • 3. Chrysophyceae • 4. Bacillariophyceae • 5. Cryptophyceae • 6. Dinophyceae • 7. Chloromonadineae • 8. Euglenineae • 9. Phaeophyceae • 10. Rhodophyceae • 11. Myxophyceae(Blue green algae)

REPRODUCTION

• Algae are capable of reproducing through asexual or vegetative methods and via sexual reproduction. 

• Asexual reproduction involves the production of a motile spore. • Vegetative methods include simple cell division (mitosis) to produce

identical offspring and the fragmentation of a colony.• Sexual reproduction involves the union of gametes (produced

individually in each parent through meiosis).

IMPORTANCE

• Probably the most important contribution of algae to our environment is the generation of oxygen through photosynthesis.

• Algae are indispensable because they produce about half the oxygen in Earth's atmosphere.

• Green algae, diatoms and cyanobacteria are just some of the microalgal species that are considered good candidates for the production of biofuel.

• Algae help to keep atmospheric carbon dioxide levels stable by storing the gas in organic materials that include oil deposits and inorganic carbonate rocks.

ALGAL BLOOM• Algae, in the form of algal blooms, get a

bad rap for creating toxic conditions in oceans and lakes.

• Algal blooms refers to the uncontrolled growth of certain microalgae, which in turn leads to the production of toxins, disruption of the natural aquatic ecosystems.

• The blooms take on the colours of the algae contained within them.

• The main toxin producers in oceans are certain dinoflagellates and diatoms. In freshwaters, cyanobacteria are the main toxin producers.

• The main cause of algal blooms is a phenomenon called nutrient pollution. With nutrient pollution, there is an excess of nitrogen and phosphorus, which can push algae toward uncontrolled growth. The phenomenon is caused by the fertilizers we use in agriculture and animal manure.

REFERENCE

• http://www.sciencedirect.com/science/article/pii/S0306261910005799• http://www.nrcresearchpress.com/doi/abs/10.1139/b77-095• https://dl.sciencesocieties.org/publications/jeq/abstracts/27/2/

JEQ0270020261

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