Algae are a diverse group of photosynthetic organisms that are found in both aquatic and terrestrial environments. They exist as both unicellular and multicellular forms and can range in size from microscopic to several feet in length. Algae play an important role as primary producers in many ecosystems and also have significant commercial uses. Some key economic products derived from algae include agar, alginates, carrageenan, and diatomaceous earth. Algae are also used as food sources in some parts of the world and can potentially be grown on waste materials as a sustainable food source. Taxonomically, algae are divided into groups based on their pigments, food reserves, life cycles, and other characteristics

1. Algae
Procaryotic, eucaryotic, photosynthetic micro and
macro organism
Unicellular, microscopic and macroscopic

2. Algae

4. Sea weeds

5. Biological and Economic importance of
Algae
1. Primary produce-
• most are aquatic
• Floating phytoplankton- food for aquatic life
2. Commercial products-
a. agar- well known solidifying agent used in
microbiology laboratory
• Obtained from red algae (marine)-Geledium and
Gracilaria
• Used in food industries for making pudding,
processed cheese, mayonnaise, jellies

9. Biological and Economic importance
of Algae
• Used as a carrier for drug in pharmaceutical
industry
• Lotion and creams also contain agar
b. Alginic acid and its salt obtained fron brown algae,
eg. Macrocystis, Agarum
• Alginates- added in ice creams for smooth
consistency
• Also in cheese and bakery products
• Paper manufacturing
• Printing of fabrics, paint thickening

11. Biological and Economic importance of
Algae
c. Carrageenan- polymer of galactose with sulfate
group
Extracted from red algae- Chondrus
Used as a stabiliser or emulsifier in icecream and
other milk products
Used as a thickening agent in shaving creams, lotion
and in the soap
Useful in textile and paper industries
d. Diatomaceous earth- composed of millions of
diatoms

16. Biological and Economic importance of
Algae
• Used in filters, non reactive chemically
• Finely divided- one gram is having 120sq mt
surface area
• Also used for polishing delicate surface area
3. Algae as food- Porphyra used in Japan(called nori
served with fish)
(red algae)

18. Chondrus

20. Palmeta

21. Gracilaria-red algae (china)

22. Chlorella

23. Advantages of algal food
• Rich source of proteins with all amino acids
essential for growth
• Good source of carbohydrate and fats as well
• Can be grown on waste materials

24. Algae and diseases
• Prototheca-1.human skin infection
• 2. bursitis- joint pain

25. Cephaleuros- plant pathogen

26. Characteristics of Algae
• Morphology- wide range
• Spherical, rod shaped, club shaped, spindle
shaped(single celled sp)
• Multicellular – complex, group of same cells or
different cells (may resemble higher plants)
• Cell wall- thin and rigid.
• Diatoms have silica and therefore thick and very
rigid.
• The motile algae have flexible cm called periplast
• Some have an outer matrix secreted through cw

28. Unicellular algae

30. Algal pigments
• Chlorophyll-a,b,c,d,e,
• a is present in all

32. Carotenoid
• Carotene- unsaturated hydrocarbon
• Xanthophyll- oxygenated derivative

33. Biloprotein (phycobilin)
• Water soluble pigment- phycocyanin and
phycoerythrin

34. Motility
• Motile algae- swimming algae
• Flagella-in pairs, clusters
• Types- whiplash (cylindrical and smooth), tinsel
(cylindrical and hair like), ribbon or strap like
• Some don’t have means of motility
• Carried about by currents, tides, waves
• Some spores are motile- zoospore
• Other structures- eye spot, knob like structure,
gelatinous stalk

40. classification
• Based on-
• Nature and properties of pigments
• Chemistry of reserve food material
• Types or number of flagella, morphology and
insertion
• Life history, reproductive structures, and methods
of reproduction
• Eg. Geledium
• Very useful commercially

42. Rhodophycophyta
• Chlorophyll a, b and phycoerythrin
• Cell wall- cellulose
• Reserve food- starch
• Red algae
• Marine forms
• Asexual reproduction- non motile spore
• Sexual reproduction- heterogamous
• (spermatia and carpogonia)

44. Xanthophycophyta(yellow-green
algae)

47. • Chlorophyll a, c rarely e
• Found in temperate environment(fresh water and
marine), also in soil
• Occur as single cell, colonies, branched and
unbranched filaments
• Flagella of unequal length
• Zoospores
• Asexual reproduction by cell division and
fragmentation
• Sexual reproduction rare
• Cell wall- cellulose, pectin
• Reserve food material- chrysolaminarin(branched
glucan), oil
• Eg Vaucheria

48. Chrysophycophyta- golden algae
• Chlorophyll a and c
• Beta carotene and fucoxanthin
• Predominantly flagellate
• Some have pseudopodia
• Some are non-motile
• Most forms are unicellular and form colonies
• Reserve food material- chrysolaminarin(branched
glucan), oil
• Eg. Ochromonas

50. Phaeophycophyta- brown algae
• Chlorophyll a and c
• Multicellular, brown pigment
• Found in marine environment
• Quite complex(some have several feet height)
• Eg brown sea weed
• Have holdfast and air bladder (give buoyancy)
• Asexual reproduction- zoospore
• Sexual reproduction- isogamous and heterogamous
• Commercial uses-food, source of iodine and mineral
salt
• Eg. Sargasso

52. Sea of Sargasso

53. Bacillariophycophyta-the Diatoms
• Chlorophyll a and c
• Found in fresh water, salt water, soil
• Abundant in cold water
• Plentiful form of plankton in Arctic
• Wide range of shape
• Unicellular, colonial and filamentous forms
• Produce shell (CW) containing silica
• These shells over the period give rise to
diatomaceous earth, commercially very important

57. Euglenophycophyta-euglenoid
• Chlorophyll a and b
• Unicellular, actively motile
• Interesting example is Euglena (animal as well as
plant features)
• Photosynthetic and contractile vacuole
• No cell wall, having periplast
• Anterior gullet and red eyespot
• Reproduction by binary fission
• Dormant cyst like structure is produced
• Paramylon, oils as reserve material

59. Chlorophycophyta- green algae
• Chlorophyll a and b
• Freshwater
• Some in marine and terrestrial environment
• One chloroplast per cell, laminate, cup shaped and
reticulate
• Chloroplast has pyrenoid- a site of starch synthesis
• Single celled and colonial forms
• Some has holdfast for attachment
• Produce zoospore
• Binary fission and isogamous, heterogamous
reproduction

60. chlamydomonas

62. spirogyra

64. volvox

65. Cryptophycophyta
• Chlorophyll a and c
• Biflagellate organisms, two unequal flagella, tinsel
type
• Cells slipper shaped
• Some have only plasmalemma
• One or two plastids with or without pyrenoid
• Reproduction by binary fission, zoospore and cyst
• Sexual reproduction is seen in some

66. Cryptomonas

67. Pyrrophycophyta- the Dinoflagellate
• Chlorophyll a and c
• Plant and animal like features
• Flagella are in girdle, one flagellum is encircling
and one trailing
• Plasmalemma and some have cellulose plates in
plasmalemma (thecal plate)
• Can produce red pigment, Gonyaulax (red tide)
• Simple cell division and occasionally sexual
reproduction

72. group chlorophyll carotenoid biloprotein Storage products
Rhodophycophyta
Red algae
a, rarely d Beta carotene
Zea xanthin
Alpha carotene
Phycoerythrin
phycocyanin
Starch, oil
Xanthophycophyta
Yellow- green algae
a, c, rarely
e
Beta carotene
Diadinoxanthin
Heteroxanthin
Chrysolaminarin,
oils
Chrysophycophyta
Golden algae
a, c Beta carotene
fucoxanthin
Chrysolaminarin,
oils
Phaeophycophyta
Brown algae
a,c Beta carotene
Alpha carotene
fucoxanthin
laminarin, oils,
carbohydrate
Bacillariophycophyta
Diatoms
a, c Beta carotene
Alpha carotene
fucoxanthin
Chrysolaminarin,
oils
Euglenophycophyta
Euglenoid
a, b Beta carotene
Alpha carotene
Diadinoxanthin
Paramylon, oils

73. group chlorophyll carotenoid biloprotein Storage
products
chlorophycophyta
Green algae
a, b Beta
carotene
Alpha
carotene
lycopene
Starch, oil
Cryptophycophyta
Cryptomonad
a,c Beta
carotene
Alpha
carotene
alloxanthin
Phycoerythrin
phycocyanin
Starch, oil
Pyrrophycophyta
dinoflagellate
a,c Beta
carotene
Alpha
carotene
Peridenin
Starch, oil