The document provides an overview of algae, detailing their classification as eukaryotic organisms and their role in ecosystems as primary producers and food sources. It highlights their biological and economic importance, including their use in food, pharmaceuticals, and biofuels, as well as issues related to harmful algal blooms. Additionally, it covers the physical characteristics, reproduction methods, and various types of algae, such as red, green, and brown algae.

1. AlgaeAlgae
Md. Saiful IslamMd. Saiful Islam
Dept. of Pharmaceutical SciencesDept. of Pharmaceutical Sciences
North South UniversityNorth South University
Facebook Group: Pharmacy UniverseFacebook Group: Pharmacy Universe
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2. IntroductionIntroduction
 Algae belong to the kingdom protistaAlgae belong to the kingdom protista
 Algae are eukaryotes (cells have organelles)Algae are eukaryotes (cells have organelles)
 Algae contain chlorophyll and are photosyntheticAlgae contain chlorophyll and are photosynthetic
 Require moist environment because they lack a waxyRequire moist environment because they lack a waxy
cuticle( cuticle prevents water loss in terrestrial plants)cuticle( cuticle prevents water loss in terrestrial plants)
 They differ from other green plants in having simple reproductiveThey differ from other green plants in having simple reproductive
structures for reproduction.structures for reproduction.
 They range from microscopic unicellular forms comparable in sizeThey range from microscopic unicellular forms comparable in size
to bcteria to seaweeds that may grow to many feet length.to bcteria to seaweeds that may grow to many feet length.
 The study of this unique group of organisms (algae) is calledThe study of this unique group of organisms (algae) is called
phycology.phycology.

3. Occurrence of AlgaeOccurrence of Algae
 Thousands of species occur in nature.Thousands of species occur in nature.
 They are of great abundance is oceans, seas, saltThey are of great abundance is oceans, seas, salt
lakes, freshwater lakes, ponds and streams.lakes, freshwater lakes, ponds and streams.
 Plankton: principal food for aquatic animals andPlankton: principal food for aquatic animals and
planktons for a large part of the free-floatingplanktons for a large part of the free-floating
microscopic life in water.microscopic life in water.
 Phytoplankton is made up of plants i.e. algal forms.Phytoplankton is made up of plants i.e. algal forms.
 Algae are normally found where there are sufficientAlgae are normally found where there are sufficient
light, moisture and simple nutrients to sustain them.light, moisture and simple nutrients to sustain them.

4. Occurrence of AlgaeOccurrence of Algae
 Some special species may grow on ice andSome special species may grow on ice and
snow.snow.
 Some can grow in hot springs at temperaturesSome can grow in hot springs at temperatures
5555ºC.ºC.
 Marine algae can adapt to the variation of saltMarine algae can adapt to the variation of salt
concentration of marine environment.concentration of marine environment.
 Algae may cause problem in water suppliesAlgae may cause problem in water supplies
because they produce undesirable taste andbecause they produce undesirable taste and
odor.odor.

5. Biological andBiological and
Economic ImportanceEconomic Importance
of Algaeof Algae
 Algae as Primary Producers:Algae as Primary Producers:
 Algae helps to fix carbon (capture carbonAlgae helps to fix carbon (capture carbon
dioxide and change into organic compoundsdioxide and change into organic compounds
like sugar) through photosynthesis.like sugar) through photosynthesis.
 They are the base of the aquatic food chain -They are the base of the aquatic food chain -
photosynthetic organismsphotosynthetic organisms
 Algae that are present in soil can help toAlgae that are present in soil can help to
increase its fertility.increase its fertility.

6. Biological andBiological and
Economic ImportanceEconomic Importance
of Algaeof Algae
 Commercial products from algae:Commercial products from algae:
 Three important products from algae are: agar , alginicThree important products from algae are: agar , alginic
acid and carrageenan which are extracted from theacid and carrageenan which are extracted from the
walls of algae.walls of algae.
 All three compounds are used either to make gels or toAll three compounds are used either to make gels or to
make solutions viscous.make solutions viscous.
 Algin- a thickening agent for food processing (brown algae),Algin- a thickening agent for food processing (brown algae),
cheese, bakery product, frostings etc.cheese, bakery product, frostings etc.
 Carrageenan – foods, puddings, ice cream, toothpaste (redCarrageenan – foods, puddings, ice cream, toothpaste (red
algae)algae)
 Agar – as solidifying agent for growth media used in researchAgar – as solidifying agent for growth media used in research
(red algae)(red algae)

7. Biological andBiological and
Economic ImportanceEconomic Importance
of Algaeof Algae
Algae as Food:Algae as Food:
 red and brown algae are mostly used as food.red and brown algae are mostly used as food.
 Red algae is a significant food in china.Red algae is a significant food in china.
Algae and DiseasesAlgae and Diseases
 A few algae can be pathogenesis to humans in causingA few algae can be pathogenesis to humans in causing
systemic and subcutaneous infections as well assystemic and subcutaneous infections as well as
bursitis (inflammation of joints).bursitis (inflammation of joints).
 Some planktonic algae produce toxins which are lethalSome planktonic algae produce toxins which are lethal
to fish and other animals.to fish and other animals.
 Shell fish poisoning may occur in humans (bloom ofShell fish poisoning may occur in humans (bloom of
dinoflagellates). The victim experience numbing of lips,dinoflagellates). The victim experience numbing of lips,
tongue and fingure tips and in serious casestongue and fingure tips and in serious cases
respiratory failure can result.respiratory failure can result.

8. Biological andBiological and
Economic ImportanceEconomic Importance
of Algaeof Algae
 Production of biofuel:Production of biofuel:
 BiofuelBiofuel is a type of fuelis a type of fuel
whose energy is derivedwhose energy is derived
from biological carbonfrom biological carbon
fixation.fixation.
 Can produce high yields ofCan produce high yields of
 Lipids for biodieselLipids for biodiesel
 starch / polysaccharides forstarch / polysaccharides for
ethanolethanol

9. Characteristics ofCharacteristics of
AlgaeAlgaeMorphologyMorphology
 Wide range of shape and size are availableWide range of shape and size are available
 May occur as single cells as spherical, rod-May occur as single cells as spherical, rod-
shaped, club-shaped or spindle shaped.shaped, club-shaped or spindle shaped.
 Others are multicellular and includeOthers are multicellular and include
membranous colonies, filaments grouped singlymembranous colonies, filaments grouped singly
or in clusters, branched or unbranched etc.or in clusters, branched or unbranched etc.
 In most species cell wall is thin and rigid.In most species cell wall is thin and rigid.
 Motile algae have flexible cell membranes calledMotile algae have flexible cell membranes called
periplasts.periplasts.
 Algae contain discrete nucleus.Algae contain discrete nucleus.
 Chlorophyll and other pigments are found inChlorophyll and other pigments are found in
membrane bound organelles called chloroplasts.membrane bound organelles called chloroplasts.
 Other inclusions include starch grains, oilOther inclusions include starch grains, oil
droplets and vacuoles.droplets and vacuoles.

10. Structure of algaeStructure of algae

11. Characteristics ofCharacteristics of
AlgaeAlgae
Algal pigmentsAlgal pigments
 Chlorophylls: Lipid soluble pigment. Helps inChlorophylls: Lipid soluble pigment. Helps in
photosynthesis and there are 5 types of chlorophyllphotosynthesis and there are 5 types of chlorophyll
present in different species of algae. Produces greenpresent in different species of algae. Produces green
color.color.
 Carotenoids: Lipid soluble pigment. There are twoCarotenoids: Lipid soluble pigment. There are two
types of carotenoids: carotenes and xanthophylls. Givetypes of carotenoids: carotenes and xanthophylls. Give
rise to orange color.rise to orange color.
 Biloproteins (phycobilins): Water soluble pigments.Biloproteins (phycobilins): Water soluble pigments.
They are present in two algal divisions. There are 2They are present in two algal divisions. There are 2
types of phycobilins: phycocyanin (blue pigment) andtypes of phycobilins: phycocyanin (blue pigment) and
phycoerythrin (red). Their proportion can varyphycoerythrin (red). Their proportion can vary
considerably with changes in nature.considerably with changes in nature.

12. Characteristics ofCharacteristics of
AlgaeAlgae
MotilityMotility
 Motile algae or swimming algae have flagellaMotile algae or swimming algae have flagella
that occur singly, in pairs or in clusters at thethat occur singly, in pairs or in clusters at the
anterior or posterior of the cell.anterior or posterior of the cell.
 Some algae have no means of locomotion andSome algae have no means of locomotion and
are carried by tides, waves and currents.are carried by tides, waves and currents.
 A small red or orange body (eyespot) isA small red or orange body (eyespot) is
present near the anterior end of motile algae.present near the anterior end of motile algae.
Other algae contain knobs on their exteriorOther algae contain knobs on their exterior
which may be anchored to some object.which may be anchored to some object.

13. Characteristics ofCharacteristics of
AlgaeAlgae
 ReproductionReproduction
Most reproduce both sexually and asexuallyMost reproduce both sexually and asexually
 Most sexual reproduction is triggered byMost sexual reproduction is triggered by
environmental stressenvironmental stress
 Asexual Reproduction: By production ofAsexual Reproduction: By production of
unicellular spores (zoospores: have flagellaunicellular spores (zoospores: have flagella
and are motile; aplanospores: non-motile).and are motile; aplanospores: non-motile).
 Sexual Reproduction:Sexual Reproduction: Spirogyra reproduceSpirogyra reproduce
sexually by conjugation.sexually by conjugation.

14. Examples of AlgaeExamples of Algae
Rhodophycophyta (red algae):Rhodophycophyta (red algae):
 4000 species of4000 species of RED AlgaeRED Algae
 Are some of the oldest eukaryotic on earth (2 billionAre some of the oldest eukaryotic on earth (2 billion
year old fossils)year old fossils)
 Most are marine; abound in tropical, warm watersMost are marine; abound in tropical, warm waters
 Smaller than brown algae and are often found at aSmaller than brown algae and are often found at a
depth of 200 meters.depth of 200 meters.
 Act as food and habitat for many marine speciesAct as food and habitat for many marine species
 Structure from thin films to complex filamentousStructure from thin films to complex filamentous
membranesmembranes
 Contain chlorophyll a and c as well as phycobilinsContain chlorophyll a and c as well as phycobilins
which are important in absorbing light that canwhich are important in absorbing light that can
penetrate deep into the waterpenetrate deep into the water

15. Examples of AlgaeExamples of Algae
 Red algae used as foodRed algae used as food
 Have cells coated in carageenan which is used inHave cells coated in carageenan which is used in
cosmetics, gelatin capsules, ice cream, jellies, syrups,cosmetics, gelatin capsules, ice cream, jellies, syrups,
breads and some cheeses.breads and some cheeses.
 Also used for lotions, toothpaste, pharmaceutical jelliesAlso used for lotions, toothpaste, pharmaceutical jellies
 Agar – extracted from cell walls of red algaeAgar – extracted from cell walls of red algae

16. Examples of AlgaeExamples of Algae
Chlorophycophyta (green algae):Chlorophycophyta (green algae):
 7000 diverse species7000 diverse species
 Largest and most diverse group of algaeLargest and most diverse group of algae
 Found mostly in fresh waters and on landFound mostly in fresh waters and on land
 Float in rivers, lakes, reservoirs, creeksFloat in rivers, lakes, reservoirs, creeks
 Can also live on rocks, trees, soilCan also live on rocks, trees, soil
 Both green algae and land plants have chlorophyll a and b asBoth green algae and land plants have chlorophyll a and b as
well as carotenoids and store food as starchwell as carotenoids and store food as starch
 Both have walls made of celluloseBoth have walls made of cellulose
 Structure of green algae from singles, filaments, colonies, thalliStructure of green algae from singles, filaments, colonies, thalli
(leaf like shape)(leaf like shape)

17. Examples of AlgaeExamples of Algae
Phaeophycophyta (brownPhaeophycophyta (brown
algae):algae):
 1500 species of1500 species of BrownBrown
algaealgae
 Mostly marine and includeMostly marine and include
seaweed.seaweed.
 Rocky coasts in temperateRocky coasts in temperate
zones or open seas (coldzones or open seas (cold
waters)waters)
 All are multicellular and largeAll are multicellular and large
(often reaching lengths of(often reaching lengths of
147 feet)147 feet)
 Cooler areas of oceanCooler areas of ocean
 Used in cosmetics and mostUsed in cosmetics and most
ice creamsice creams

18. LichensLichens
 Lichens are composite organisms ofLichens are composite organisms of
algae or cyanobacteria inalgae or cyanobacteria in
association with fungi.association with fungi.
 They grow on rocks and tree barks.They grow on rocks and tree barks.
 Many lichens are able to grow at lowMany lichens are able to grow at low
temperatures found at high altitudestemperatures found at high altitudes
and in polar environments. E.g.and in polar environments. E.g.
reindeer mosses.reindeer mosses.
 The colors of lichens vary from whiteThe colors of lichens vary from white
to black through shades of red,to black through shades of red,
orange, yellow and green.orange, yellow and green.

19. LichensLichens
 Morphology: a simple lichen is made up of a top layer ofMorphology: a simple lichen is made up of a top layer of
tightly woven layer of tightly woven fungal mycelia, below thistightly woven layer of tightly woven fungal mycelia, below this
is a layer of photosynthetic cells and below that another layeris a layer of photosynthetic cells and below that another layer
of fungus.of fungus.
 Reproduction: Both sexual and asexual.Reproduction: Both sexual and asexual.
 Lichens grow slowly because of their slow metabolic rate.Lichens grow slowly because of their slow metabolic rate.
(45000 years for some species in the arctic region).(45000 years for some species in the arctic region).

20. LichensLichens
Symbiotic nature:Symbiotic nature:
 Algae or cyanobacteria provides the fungusAlgae or cyanobacteria provides the fungus
with food (carbohydrates produced fromwith food (carbohydrates produced from
photosynthesis and with vitamins).photosynthesis and with vitamins).
 Fungi absorb and store and supplies water andFungi absorb and store and supplies water and
minerals as well as carbon dioxide. They alsominerals as well as carbon dioxide. They also
provide a moist sheltered supportingprovide a moist sheltered supporting
framework for its photosynthetic partner.framework for its photosynthetic partner.

21. LichensLichens
Chemical interactions:Chemical interactions:
 Contains unusual fats and phenolicContains unusual fats and phenolic
compounds.compounds.
 Litmus (a well known indicator) is obtainedLitmus (a well known indicator) is obtained
from lichens.from lichens.
 Lichen pigments can be used to color clothes.Lichen pigments can be used to color clothes.
 Essential oils from some species of lichens areEssential oils from some species of lichens are
used as perfumes.used as perfumes.