REG. NO.- 161103004
M.Sc. BIOTECHNOLOGY 1ST YEAR
• 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
• 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.
• 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) Non motile:- A single non-motile cell
carrying out all essential functions of
life. Flagella is absent.
b) Motile:- A single cell with flagella for
E.g.- Chlamydomonas Chlorella
Colony is formed by aggregation of
Non motile colony:- Individual cell
in the colony lacks flagella.
Parenchymatous forms:- Cell
division and associated septation leads
to the formation of a parenchymatous
• 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.
• Algae are capable of reproducing through asexual or vegetative methods and via
• 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).
• 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
• 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.
• Algae, in the form of algal blooms, get a bad
rap for creating toxic conditions in oceans and
• Algal blooms refers to the uncontrolled growth
of certain microalgae, which in turn leads to the
production of toxins, disruption of the natural
• 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.
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