Algae: Occurrence, types, classification, economic importance
- Introduction to algae.
- Economic importance.
Introduction to algae
- 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.
- 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.
Characteristics of algae
- 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.
- There are three kinds of photosynthetic pigments are present in algae:
- biloproteins or phycobilins
- 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.
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
- Algae may be reproduce asexually or sexually.
- Unicellular algae reproduce asexually by mitosis.
- Multicellular algae also reproduce asexually either by vegetative means or by mitotically produced asexual spores called Mitospores.
Some common example of mitospores are:
- Zoospores– flagellate motile spores.
- Aplanospores– non- motile spores.
- Autospores– non – motile produces by chlorella.
Sexual reproduction involves:
- Gamete formation
In algae three distinct type of sexual life cycles are reported.
- Sex organs of algae is Gametangia.
- Antheridium – Male sex organs.
- Oogonium – Female sex organ.
- If the two gametes are look alike neither male nor female, such gametes are called, isogametes, infusion process is isogamous. Example – In spirogyra.
- If the two gametes differ in size, these gametes are Anisogametes and the fusion process of anisogametes are referred as Anisogamous Example – In Chlamydomonas.
- Smaller one is male and the larger one is female.
- The female gamete (egg) is large and non motile and the male gamete is small and motile such gametes are oogametes and fusion process is Known as oogamy. Example – In Volvox, fucus.
Classification of alage
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.
Green algae – Chlorophyceae
- 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).
Red algae – Rhodophyceae
- 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.
Brown algae – Phaeophyceae
- 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.
Economic importance of algae
- 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.
Reference and Sources
- 1% – https://www.biologydiscussion.com/algae/algae-definition-characteristics-and-structure-with diagram/46727
- 2% – https://projectandmaterials.com/general-characteristics-of-algae/
- 1% – https://www.pbs.org/wgbh/evolution/library/glossary/index.html
- 1% – https://www.yourarticlelibrary.com/essay/algae/essay-on-algae-top-21-essays-onalgae/83242
- 1% – https://www.britannica.com/science/algae/Reproduction-and-life-histories
- 1% – https://www.biologydiscussion.com/essay/essay-on-protozoa-zoology/25001
- 1% – https://quizlet.com/120596279/exam-1-plant-diversity-and-evolution-flash-cards/
- 1% – https://www.sciencedirect.com/science/article/pii/B9780128123607000045
- 1% – https://wikimili.com/en/Pyrenoid
- 1% – https://www.slideshare.net/227777222an/five-kingdom-classification-127056921
- 1% – https://www.evidyarthi.in/cbse/classxi/biology/plant-kingdom-class-11-biology-chapter3notes
- 1% – https://en.wikipedia.org/wiki/Agar
- 1% – https://www.sciencedirect.com/science/article/pii/S0065229619301193
- 1% – https://www.wikidoc.org/index.php/Algae
- Microbial Fuel Cells
- Transposable Elements
- Measurements of microbial growth
- Polymerase Chain Reaction
- Electrophoresis: Overview, Principles and Types
- Bacterial Growth Curve: Definition, Phases and Measurement
- Granulocytes: Introduction, Types, Functions and Roles
- Gel electrophoresis: types, principles, instrumentation and applications
- Whole-Genome Shotgun Sequencing: overview, steps and achievements
- Milk: Composition, Processing, Pasteurization, Pathogens and Spoilage
- Agglutination reaction: Definition, Uses and Application
- Cyanobacteria: occurrence, morphology, structure, reproduction
- Bacteria: Shape, Size, Structure and other Membrane
- Plasmid: Properties, Types, Replication and Organization
- Fungi: Distribution, Morphology, Reproduction, Classification
- Spectroscopy: Introduction, Principles, Types and Applications
- Overview of Viroids, Satellites and prions
- Proteomics: Introduction, Methods, Types and Application
- Riboflavin: Fermentation, Harvesting and Uses
- Nosocomial Infection: Introduction, Source, Control and Prevention
- Major histocompatibility complex (MHC): introduction, types and differences