This document discusses the classification, characteristics, and economic importance of algae. It begins by outlining Linnaeus' original classification of algae in 1753 and notes that many algae are unicellular. It then discusses the morphology, pigments like chlorophyll and carotenoids, and cell structure of algae including chloroplasts and thylakoids. The three main groups - green, red, and brown algae - are classified based on their primary pigments, storage products, cell wall composition, and flagella. Examples of commonly known algae from each group are also provided. The document concludes by explaining the economic importance of algae as primary producers and sources of commercial products like agar, alginic

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

5.  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

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

7. 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.

8. 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 – Phycocyanin, Phycoerythrin

9.  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

11.  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

13.  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

15.  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

17.  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

18.  https://www.biologydiscussion.com/algae/algae-definition-
characteristics-and-structure-with diagram/46727
REFERENCES