This document provides an overview of the phyla Phaeophyta (brown algae), Rhodophyta (red algae), and Chlorophyta (green algae). It outlines their key characteristics, classification, reproduction processes, and economic importance. The lesson objectives are to enable students to identify and compare features of brown, red, and green algae, describe their life cycles including meiosis and fertilization points, and understand their ecological and economic roles. Examples of life cycles discussed include Laminaria, Gracilaria, Chlamydomonas, and Ulva.
1. Phylum Phaeophyta [Brown Algae]
Presented by:
Fasama Hilton Kollie
Lecturer, Department of Biology
Mother Patern College of Health Sciences
March 11, 2019
2. Lesson Outline
• Overview of the Phylum Phaeophyta, Rhodophyta and Chlorophyta
• General characteristics of brown, red and green algae
• Classification of red and green algae
• Reproduction in multicellular algae;
• Life cycle of Laminaria
• Life cycle of Gracelaria
• Chlamydomonas life cycle
• Ulva life cycle
• Ecological and economic importance of brown, red and green algae
3. Lesson Objectives
• Upon completion of this topic, students will be able to;
• Identify the basic features of brown, red and green algae
• Identify how multicellular algae differs in structure and form from
other members of the unicellular algae and one from another
• Describe the structure and function of holdfasts, stipes, blades,
bladders, and thalli multicellular algae
• Draw and discuss the life cycles of luminaria, Gracelia,
Chlamydomonas and Ulva ; indicating where meiosis and fertilization
occurs
4. Phylum Phaeophyta: Brown Algae
• Group of multicellular, eukaryotic
organisms that belong to the class
phaeophyceae in the division
chromophyta
• Commonly referred to as Brown algae
• Consist of about 1,500 species
• Only 6 of the above is found in freshwater
• 99% are marine organisms
5. General Characteristics: Habitat & Habit
• 99% of the brown algae species are
found in the marine environment
• They basically only exist in
saltwater forms
• Few freshwater organisms
• Solitary, non-motile organism
6. General Characteristics: Size
• Among the brown algae are the largest
of all algae, the Giant kelps
• May reach a length of over 100 ft (30 m)
or more
• Lobophora variegata
• Seen in clear tropical waters in
Bahamas
• Grow's at a depth of 220 meters (730
feet)
10. • Consist of tiny species such as Ralfsia expansa, commonly know as tar spot
Size Cont’d…
Ralfsia expansa
Ralfsia forgiformis
Ralfsia verrucossa
11. General Characteristics: Morphology
• Brown algae have a plantlike body
called Thallus
• The complete body of a seaweed
• Thalli are typical of algae, fungi,
lichens, and some liverworts.
Sea lettuce (Ulva)
12. • Kelp thallus has three main parts
• Holdfast
• Stipe
• Blades
• Contain gas-filled floats (Bladder)
Pneumatocyst
Morphology Cont’d…
Thallus
15. • Algin or alginic acid occurs on or in the cell walls of brown algae
• It constitute about 40% of the dry weight of some kelps
General Characteristics Cont’d…
17. General Characteristics: Mode of Nutrition
• Brown algae are generally
photosynthetic
• Consist of chlorophylls a and c
• Plastid has large amount of
fucoxanthin which gives them a
characteristic brown or olive color
• Their main food reserve is
Laminarin
18. Reproduction In Brown Algae
• Undergo both asexual and sexual reproduction
• Several other brown algae reproduce asexually by fragmentation
• Eg; sargassum
Sargassum muticum
20. • Sexual reproduction is common and associated with gametes
• They have a life cycle in which there is an alternation of
heteromorphic generations
• Brown algae have large and conspicuous sporophyte
• Gametophyte is microscopic
Reproduction In Brown Algae
Cont’d..
23. Phylum Rhodophyta: Red Algae
• A large Phylum of the Kingdom Protista,
consisting of mostly multicellular aquatic
organisms
• Commonly referred to as Rhodophytes or
Red algae
• Appx 5,000 species
• Eg: Polysiphoni, Porphyra,
Batrachospermum, Corallin
24.
25. General Characteristics Cont’d…
• Red algae may have been the first eukaryotes
formed by endosymbiosis involving
photosynthetic prokaryotes
• Found in both marine and freshwater
environment
• Approximately 5% of the red algae occur in
freshwater environments with greater
concentrations found in the warmer area
• Consist of thallu-like body measuring up to
about 10 centimeters (3.9 inches) in length
26. General Characteristics Cont’d…
• Different species may be free living,
epiphytic, or parasitic
• Contain chlorophyll a and d
• Phycoerythrin, Phycocyanin, and
allophyocyanin as accessory pigments
• cell walls of red algae have cellulose as a
framework and mostly mucilages in
nature containing agars and carageenans
27. General Characteristics Cont’d…
• Some do contain calcium
carbonate in their cell wall. Such
organisms are commonly referred
to as Coralline algae
• Not all red algae are red, Some
are blue-green or olive
• Absence of flagella and centriole
Coralline algae
28. Classification of Red Algae
• There are two classes of red algae namely:
• Florideophyceae
• Bangiophyceae
• Both Florideophyceae and Bangiophyceae comprise 99% of red algae
diversity in marine and freshwater habitats.
31. • Unicellular, filament, blade structure
• Have diffuse growth pattern
• E.g. Porphyra
Classification of Red Algae
• Bangiophycidae (1%):
Porphyra
32. Reproduction In Red Algae
• Red algae are know for the complexity of their life cycles
• Most have three(3) multicellular phases;
• A haploid gametophyte
• Two diploid sporophytes
• One of the sporophytes phases, Tetrasporophyte, produces spores
called tetraspores by meiosis
• Tetraspores germinate and grow into male or female gametophyte
33. Reproduction In Red Algae
• Male gametophytes release nonflagellated gametes, called
spermatia
• Spermatia is transported to female gametophyte via water current
• Following fertilization, the zygote divides repeatedly by mitosis,
producing the second sporophyte phase, Carposporophyte
• This remain attached to the female gametophyte
35. Reproduction In Red Algae
• Carposporophyte releases spores called carpospores
• This develop into new tetrasporophytes
36. Economic Importance
• Red algae are ecologically significant as primary producers, providers
of structural habitat for other marine organisms, and their important
role in the primary establishment and maintenance of coral reefs.
• Some red algae are economically important as providers of food and
gels. For this reason, extensive farming and natural harvest of red
algae occurs in numerous areas of the world
39. Phylum Chlorophyta: Green Algae
• Green algae
• From two Greek roots chloros- “Green” and phyta – “Plant”
• The reference is to the typical color of member of the phylum
• 7,500 extant species
40. General Characteristics: Habitat & Habit
• Most live in fresh water
• Some serve as seaweeds or parts of
phytoplankton in oceans
• Others are terrestrial, growing in moist
places favored by mosses and ferns
• Some establish symbiotic relationships
with other organisms
• Eg: Lichens
41. General Characteristics: Size
• Some are unicellular and
microscopic
• The green alga Micromonas
is only 1 µm in diameter—
the smallest eukaryotic cell
known
Micromonas pusilla
42. General Characteristics: Morphology
• Green algae species shows different body type
• Some may be unicellular
• Some colonial
• Filamentous as in Ulothrix and Spirogyra
• Some plant-like marine forms as in Fristschiella and Ulva
Chlamydomonas
43. Morphology Cont’d…
• The cells possess one to many
chloroplast
• Green algae have Chlorophyll a
and b, carotenes and
xanthophylls
• They store starch inside plastids as
a food reserve
44. General Characteristics Cont’d…
• Green algae share numerous
characteristics with plants
̶ Have chlorophylls a and b
̶ Use sugar and starch as food reserves
̶ Many have cell walls of cellulose
45. Classification of Green Algae
• There are several classes of green algae that comprise of about
7,500 extant specie
• Class Chlorophyceae
• Class Ulvophyceae
• Class Charophyceae
46. Class Chlorophyceae: Chlamydomonas
• Most unicellular or colonial organisms
• Eg; Chlamydomonas
• A unicellular freshwater alga commonly
found in ponds
• Each cell has two flagella with single
chloroplast
• Reproduce both asexually and sexually
48. Class Chlorophyceae
• Both methods begin when a mature, haploid cell divides two or
more times by mitosis, producing up to 16 daughter cells
• These cells develop flagella before breaking out of parent cell’s wall
• In asexual reproduction, the daughter cells are zoospores
• They develop directly into mature haploid cells
49. Class Chlorophyceae Cont’d…
• In sexual reproduction, daughter cells are gametes
• Gametes are Isogametes and are designated either + or – mating
type
• Zygote form by fusion of + and – mating type which secretes a thick
wall
• The wall zygote is know as a zygospore
• The zygote produces four flagellated haploid cells inside the wall by
meiosis
51. Chlorophycean: Chlorella
• Chlorella is another unicellular
chlorophycean
• It’s studied as one of the possible food
source for humans
• Almost entirely digestible
• It weights almost 50% protein
• It grows rapidly in sewage or waste medium
52. Chlorophycean: Volvox
• Volvox is the best-known colonial
chlorophycean
• It consist of few hundred to thousand
photosynthetic cells arranged in a single
layer at the surface of a hollow sphere
• Consist of a light detector
• This controls the beating of their flagella
and directs the colony toward light
53. Class Ulvophyceae
• Ulva is a marine ulvophycean
• Found attached to rocks in
tide pools and exposed areas
Sea lettuce (Ulva)
54. Class Ulvophyceae Cont’d…
• Reproduce asexually and sexually
• Life cycle involves an alternation of isomorphic generations
• Both are bright green, flat thalli resembling a thin rubbery leaf of
lettuce
• Gametophytes are designated + or – mating string
56. Class Ulvophyceae Cont’d…
• Example of other ulvophyceans
• Acetabularia
• Cephaleuros
• Cladophora, Codium
• Acetabularia is usually found in warm
tropical water where it exist as a single cell
for most of its life
• Cephaleuros lives on the leaves of tea plants
and is responsible for red rust
58. Class Charophyceae
• Charophyceans include unicellular, colonial,
and multicellular green algae
• The Coleochaetles and Charales are the two
orders of charophyceans with the closest
relatives of plants
• Coleochetales consist of filamentious algae
that live in shallow regions of freshwater
• Eg: Coleochaete
59. Class Charophyceae
• Charales charophyceans form
mineralized cell walls
• Contains CaCO3 and MgCO3
• Stoneworts
• Eg: Chara
60. Reference
• Nabors, Murray W., IntroductionTo Botany. Copyright 2004 Pearson
Education, Inc., publishing as Benjamin Cummings, 1301 Sansome St.,
San Francisco, CA 94111. www.aw-bc.com
• https://en.m.wikipedia.org/wiki/Alginic_acid
• Davies,JC (2002). "Pseudomonas aeruginosa in cystic fibrosis: pathogenesis
and persistence". Paediatric Respiratory Reviews.
61. “Disciplining yourself to do what you know is right and
important, although difficult, is the highroad to pride, self
esteem, and personal satisfaction. ”
Margaret Thatcher
62. Nelson Mandela
“ What counts in life is not the mere fact that we have
lived. It is what difference we have made to the lives of
others that will determine the significance of the life we
lead.”
Editor's Notes
Multicellular eukaryotic organism that belonging to a large group of organisms that includes many seaweeds,
typically olive brown or greenish in color.
They contain xanthophyll in addition to chlorophyll.
CHROMOPHYTA:
Chromista is an eukaryotic kingdom, probably polyphyletic
Includes all organisms that in which their plastid contain chlorophyll a and c
as well as various colorless forms that are closely related to them.
as well as various colorless forms that are closely related to them.
265 known genera
Usually the largest, in terms of size, group of plant-like protist
Macrocystis pyrifera, [giant kelp or giant bladder kelp]
Giant kelp is one of four species in the genus Macrocystis
Individual algae may grow to more than 45 metres (150 feet)
Giant kelp grows in dense stands known as kelp forests,
which are home to many marine animals that depend on the algae for food or shelter.
The primary commercial product obtained from giant kelp is ALGINATE
but humans also harvest this species on a limited basis for use directly as food, as it is rich in iodine, potassium, and other minerals
The height of each storey is based on the ceiling height of the rooms plus the thickness of the floors between each pane.
Generally this is around 10 feet (3 m)
THALLUS:
A plant body that is not differentiated into stem and leaves and lacks true roots and a vascular tissue system.
Thalli are typical of algae, fungi, lichens, and some liverworts
HOLDFAST:
Structure that attached the organism to substrates
Substrate: A surface that serves as a base for a sessile marine organism
STIPE:
Stem-like structure which serves as a connective unit
It connects the blades to the holdfast
BLADES
leaf-like structure which aids in the process of photosynthesis
Its meristematic region is at its tip of base where the bladder is situated
Blades c
BLADDER
Air-filled floats
Structure that contains air, specifically carbon monoxide, for buoyancy
The function of this particular gas has not yet been determined.
Alginic acid
is a naturally occurring hydrophilic colloidal polysaccharide obtained from the various species of brown seaweed (Phaeophyceae).
Alginic acid, also called algin or alginate,
is a polysaccharide distributed widely in the cell walls of brown algae, where through binding with water it forms a viscous gum.
Combined with water, it turns into a gel that sets firmly enough to use as a mold.
Alginate is a biomaterial that has found numerous applications in biomedical science and engineering due to its favorable properties, including biocompatibility and ease of gelation. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, and tissue engineering applications to date, as these gels retain structural similarity to the extracellular matrices in tissues and can be manipulated to play several critical roles. This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers.
Alginate absorbs water quickly, which makes it useful as an additive in dehydrated products such as slimming aids, and in the manufacture of paper and textiles. It is also used for waterproofing and fireproofing fabrics, in the food industry as a thickening agent for drinks, ice cream and cosmetics, and as a gelling agent for jellies
Laminaria saccharina
The molecule laminarin is a storage glucan found in brown algae. It is used as a carbohydrate food reserve in the same way that chrysolaminarin is used by phytoplankton, especially in diatoms.
Laminaria is a source of the relatively rare element, iodine, which is commonly used to promote thyroid health.[13]
Certain carbohydrates such as mannitol, laminarin, and alginate can be extracted from laminaria. Mannitol is used to decrease high intraocular pressure, and to lower excessive intracranial pressure. Laminarin has two forms, soluble and insoluble. The soluble form of Laminarin has high antitumor activity, can be used in the treatment of antibiotic-resistant nosocomial infections, can aid in normalizing enteric metabolism, helps to improve enzymatic processes of the intestine and does not possess antigenic or pyrogenic properties. Laminarin continues to be of active study in today’s medical field
Laminaria is a genus of 31 species of brown algae commonly called "kelp“
Laminaria expresses a haplo-diplophasic life history, in which it alternates from a macroscopic thallic sporophyte structure, consisting of the holdfast, a stipe, and the blades,
to a filamentous, microscopic gametophyte
The sporophyte structure of laminaria can grow to 7 metres (23 ft), which is large in comparison to other algae, but still smaller than the giant kelps such as Macrocystis and Nereocystis, which can grow up to 40–50 metres (130–160 ft).
In an isomorphic alternation of generations (found in some algae, for example) the sporophyte and gametophyte are morphologically similar or identical; in a heteromorphic alternation of generations they are dissimilar (e.g. in mosses the gametophyte is the dominant and conspicuous
Phylum Rhodophyta consist of a large group of eukaryotic, multicellular organisms commonly referred to as red algae
Called red algae due to the characteristic colour showed by these organisms
Though not all organism under this division do portray a red colour
Some have the dominant pigment, Phycobillin and charactenoid, which gives them their characteristic red or pink colour
5,000 extant species
2nd larges of the multicellular algae
3rd larges of both multicellular and unicellular algae [chlorophyta 7,500, Bacillariophyta 5,600, rhodophyta 5,000, Dinophyta 3,000 and the least cryptophyta 200]
Gracilaria is a genus of red algae (Rhodophyta) notable for its economic importance as an agarophyte, as well as its use as a food for humans and various species of shellfish
It is assumed by phycologist that Red algae may have been the first eukaryotic organism formed by endosymbiosis
WHY IS THIS ASSUMED?
Habitat:
Marine (majority)
Freshwater ( about 100 species have been study)
Morphology:
They have a thallus-like body
An undifferentiated by that is not differentiated into true roots, stem and leaves
HABIT IN HABITAT:
Free living, epiphytic or parasitic
Phycobilins and carotenoids give many red algae their characteristics red or pink color
Phycocyanin absorp orange and red and give out blue colour
Allophyocyanin absorbs red light only and gives out blue colour
Note: Not all red algae are red
Eg: Halosaccion, specific species (Chandrus crispus) are often blue-green or olive
They contain less of phycobilins and carotenoids but other dominant accessory pigments associated with such colour
Cell Wall Component:
Cellulose (agar and carageenans)
Calcium carbonate (coralline)
Red algae are classified into tow classes on what basis?
Florideophytceae
Why the name?
The largest group of red algae that colonized a marine ecosystem (98%/99%)
Thread-like in appearance (filamentous)
Triphasis (life cycle of 3 phases)
Pseudoparenchymatous? Meaning……………………………….
pseudoparenchyma A tissue that superficially resembles plant parenchyma but is made up of an interwoven mass of hyphae (in fungi) or filaments (in algae).
Examples of pseudoparenchymatous structures are the fruiting bodies (mushrooms, toadstools, etc.) of certain fungi and the thalli of certain red and brown algae.
2nd most abundant red algae in marine environment
1% of the 99% of marine red algae
Interestingly, Vast majority of red algae a multicellular
However, unicellular form also exist
Class Bangiophycidae consist of unicellular species
This number is infinitesimal / mammoth
Have diffuse growth pattern meaning………
Diffuse Pattern. A morphologic architectural pattern in which a cellular population is distributed in a relatively uniform fashion throughout a specified tissue area; not focal.
Red algae are best known for the complexity of their life cycle
Most organisms here have 3 Multicellular phases:
1 - Haploid gametophyte
2 – Diploid sporophyte
Sporophyte phase:
Carposporophyte (2nd sporophyte phase)
Tetrasporophyte (1st sporophyte phase)
Red algae are best known for the complexity of their life cycle
Most organisms here have 3 Multicellular phases:
1 - Haploid gametophyte
2 – Diploid sporophyte
Sporophyte phase:
Carposporophyte (2nd sporophyte phase)
Tetrasporophyte (1st sporophyte phase)
The entire life cycle of Gracelaria begins with the 1st sporophyte phase, tetrasporophyte
Tetrasporophyte produce spores from the thallus body called tetraspores
Under conducive conditions, right temp, available water etc, tetraspores undergo meiosis and develop into gametophytes
Male gametophytes release nonflagellated games, called spermatia
Spermatia is transported to the female gametophyte via water current
Following fertilization, the zygote divides repeatedly by mitosis, producing the second sporophytes phase, carposporopyte
Carposporophytes releases spores called carpospores
Carpospores develop into new tetrasporophyte
The cycle continues
Ecological Importance
Serve as primary producers
Provide habitat for other marine organisms
Helps in maintaining coral reefs
Economic Importance
Source of food
Provide gels (cell wall is made of cellulose but is gelatinous/mucilage/gel-like)
Agar and carrageenan serves as hardeners
Multicellular eukaryotic organisms
Called Green algae for short due to their appearance – Green
Chlorophyta – “ Green” – “Plant”
7,500 species
Largest group of algae to exist
They are of particular interest because the group from which land plants evolved, the charophyta, are green algae.
The "green algae" is a paraphyletic group because it excludes the Plantae. Like the plants, the green algae contain two forms of chlorophyll, which they use to capture light energy to fuel the manufacture of sugars, but unlike plants they are primarily aquatic.
Micromonas pusila
Smallest know eukaryotic organism
Micromonas is a group of small unicellular pear-shaped micro-algae that do not have a cell wall
Carotene and Xanthophyll are types of plant pigments that plays a role in the metabolism of plants.
Xanthophyll -> These are the yellow pigment of the leaves and are classified as accessory pigments which absorbs the wavelength that chlorophyll cannot absorb. They serve as protection to excessive amount of sunlight to prevent further damage in the plan
Carotene -> These are orange photosynthetic pigments found in plants and plays an important role in photosynthesis
There are four kinds of carotene known: alpha and beta carotene, lycopene and rhodopsin. Similar to xanthophylls, they have antioxidant properties.
Characteristics b/w Green algae and plants
Photosynthetic eukaryote with chlorophyll a and b
chloroplasts of green algae are enclosed in a double membrane just as a plant
Store excess sugar as starch
Cell wall made up of cellulose
DIFFERENCE:
Green algae can be unicellular or multicellular whereas plants are multicellular organisms
Algae mostly dwell in aquatic environment where plants can survive both and land and in water
Algae lacks vascular tissues, plants do have vascular tissues
What is the basis of classification of algae? The presence or absence of pigments is the main basis of classification of algae. Chlorophyceae: Chlorophyll a and b are present in them and impart green colour.
Chlamydomonas is a genus of green algae consisting of about 325 species
all unicellular flagellates,
found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae
Red eyespot and a cell wall that lacks cellulose
What is the cell wall component of Chlamydomonas since it lacks cellulose?
Chlamydomonas reinhardtii is a single-cell green alga about 10 micrometres in diameter that swims with two flagella
It has a cell wall made of hydroxyproline-rich glycoproteins
GLYCOPROTEINS:
any of a class of proteins that have carbohydrate groups attached to the polypeptide chain. Also called glycopeptide.s
Asexual Reproduction:
Zygospore:
A thick-walled, resting spore formed by conjugation of two isogametes, as in certain primitive fungi and certain green algae.
A zygospore is a diploid reproductive stage in the life cycle of many fungi and protists.
Zygospores are created by the nuclear fusion of haploid cells.
zygospores are formed by the fusion of unicellular gametes of different mating types.
Population of haploid (n) cells grow by repeated mitotic division
Low nitrogen or other environmental change stimulates cell to develop into gametes. Games of different mating types (+ and _) are released
Mating occurs b/w games of opposite types
A diploid (2n) dormant zygote forms and develops a tough wall (Zygospore)
Zygote divides by meiosis, yielding four haploid cells
Considerable past research has shown that limiting nutrients such as nitrogen and phosphorus increases the cellular lipid content in microalgae.
Zygospore:
A thick-walled, resting spore formed by conjugation of two isogametes, as in certain primitive fungi and certain green algae.
A zygospore is a diploid reproductive stage in the life cycle of many fungi and protists.
Zygospores are created by the nuclear fusion of haploid cells.
zygospores are formed by the fusion of unicellular gametes of different mating types.
The name Chlorella is taken from the Greek χλώρος, chloros, meaning “green”, and the Latin diminutive suffix ella, meaning “small”
There are over 30 different species,
but two types — Chlorella vulgaris and Chlorella pyrenoidosa — are most commonly used in research (2).
Chlorella is a genus of single-celled green algae belonging to the division Chlorophyta
It is spherical in shape, about 2 to 10 μm in diameter
Lack flagella
contains the green photosynthetic pigments chlorophyll-a and -b in its chloroplast
Many people believe Chlorella can serve as a potential source of food and energy because its photosynthetic efficiency
Photosynthetic efficiency – is the fraction of light energy converted into chemical energy during photosynthesis is plants and plant-like protist
Chlorella is a potential food source because it is high in protein and other essential nutrients;
when dried, it is about
45% protein,
20% fat,
20% carbohydrate,
5% fiber, and
10% minerals and vitamins.
RESEARCH
9 impressive health benefits of chlorella
Volvox is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae
It forms spherical colonies of up to 50,000 cells.
They live in a variety of freshwater habitats
were first reported by Antonie van Leeuwenhoek in 1700
The cells swim in a coordinated fashion
The cells have anterior eyespots that enable the colony to swim towards light.
Ulva lactuca, also known by the common name sea lettuce
Lactuca meaning lettuce
They are group of edible for of green algae
is an edible green alga in the family Ulvaceae.
Ulva lactuca is a thin flat green algae growing from a discoid holdfast.
It may reach 18 centimetres (7.1 in) or more in length
Green to dark green in colour
The chloroplast is cup-shaped
Syngamy (fertilization)
the fusion of two cells, or of their nuclei, in reproduction.
Cladophora is a genus of reticulated filamentous Ulvophyceae (green algae)
Constitute unicellular, multicellular and colonial green algae
Coleochetales filamentous
Coleochaete is a genus of parenchymatous charophyte green algae in the order Coleochaetales
They are haploid, reproduce both sexually and asexually
Have true multicellular organization