Sailent features of different groups of algae

Sailent features of different groups of algae in microalgae technology

1. SALIENT FEATURES OF DIFFERENT GROUPS OF AL GAE
SUBJECT: MICROALGAL TECHNOLOGY presented by
Dharanipriya Sellappan
I M.sc MICROBIOLOGY
Department of microbiology
Vivekanandha arts and science college for women
Sankagari,Salem, Tamilnadu, India

2. CONTENT
Introduction of algae
Introduction of salient features
General salient features of algae
major groups of algae

3. INTRODUCTION OF ALGAE
Algae are diverse, aquatic, photosynthetic organisms that
range from microscopic to giant kelp, lacking true roots, stems,
or leaves and possessing a simple, thalloid body. These
eukaryotic (and some prokaryotic) organisms are crucial
primary producers in many ecosystems, providing food and
oxygen, while also having significant roles in human life, such
as in food, medicine, and even as environmental indicators.

4. INTRODUCTION OF SALIENT FEATURES
Salient features of algal groups are classified by their pigments,
food reserves, cell wall composition, flagella, and life cycles,
with major groups including Chlorophyceae (Green Algae),
Phaeophyceae (Brown Algae), and Rhodophyceae (Red Algae).
Green algae possess chlorophyll and store starch, brown algae
have fucoxanthin and laminarin, and red algae have
phycoerythrin and store floridean starch, with each group
exhibiting distinct cell wall materials and flagellar structures.

5. GENERAL SALIENT FEATURES OF ALGAE
Thalloid body :
The thalloid body of algae refers to its
vegetative structure, which is a simple,
undifferentiated body lacking true roots,
stems, and leaves, unlike higher plants. It can
range from a single cell to complex filaments
or plate-like structures. This simple
organization lacks specialized tissues and
organs but may have root-like structures
called rhizoids for anchorage and absorption.

6. Cellular structure :
Algal cells are classified as either prokaryotic
(like cyanobacteria) or eukaryotic (most other
algae), each with distinct structures. Prokaryotic
cells lack a membrane-bound nucleus and
contain a pigmented cytoplasm with DNA in the
centroplasm. Eukaryotic algal cells possess a
defined nucleus and other membrane-bound
organelles, including chloroplasts for
photosynthesis, mitochondria, Golgi bodies, and
often flagella for motility. Both types of cells are
surrounded by a cell wall, which varies in
composition depending on the species.

7. Pigment :
Pigments in Algae | EasyBiologyClassAlgae contain three main
classes of photosynthetic pigments essential for capturing light
energy: chlorophylls (like chlorophyll a and b), carotenoids (which
include carotenes and xanthophylls), and phycobilins. Chlorophyll a is
a primary photosynthetic pigment found in all algae, while other
pigments like chlorophyll b, various carotenoids (e.g., fucoxanthin,
astaxanthin), and phycobilins (phycocyanin, phycoerythrin) are
accessory pigments that define the colors of different algal groups
and transfer light energy to chlorophyll a.

8. Reserve food :
The reserve food in algae varies by group but often
includes starch (in green and red algae), mannitol and
laminarin (in brown algae), oil droplets, and sometimes
proteinaceous compounds like cyanophycin. The
specific reserve food depends on the algal division,
with different types of starch (like Cyanophycean
starch or Floridean starch) characteristic of certain
groups.

9. Flagella :
Flagella in algae are whip-like, protein-based
structures used for cell movement and
navigation in aquatic environments. They are
a crucial taxonomic feature for classifying
algae and are structurally complex, typically
featuring a "9+2" arrangement of
microtubules, similar to cilia. There are two
main types: smooth whiplash (acronematic)
flagella and tinsel (pleuronematic) flagella,
which are adorned with fine filaments called
mastigonemes.

10. MAJOR GROUPS OF ALGAE
Cyanophyceae (Cyanobacteria)
Chlorophyceae (Green algae)
Phaeophyceae (Brown algae)
Rhodophyceae (Red algae)
Xanthophyceae (Yellow-green algae)
Bacillariophyceae (Diatoms)

11. CHLOROPHYCEAE ( Green algae)
Green algae are considered the ancestors of land plants due to their shared
pigment composition and food storage.
Cell structure: Eukaryotic, with a rigid cell wall composed of an inner layer of
cellulose and an outer layer of pectose.
Pigmentation: Chlorophyll
and
are dominant, giving them a bright green color.
Food storage: Primarily stores food as starch within bodies called pyrenoids,
which are located in the chloroplasts.
Reproduction: Reproduces vegetatively by fragmentation, asexually by
flagellated zoospores, and sexually (isogamous, anisogamous, or oogamous).
Distinguishing feature: Has diverse body forms, including unicellular, colonial
(e.g., Volvox), and filamentous (e.g., Spirogyra).

12. PHAEOPHYCEAE ( BROWN ALGAE )
These algae are almost exclusively marine and show a wide range of sizes and
forms.
Cell structure: Multicellular and eukaryotic. Cell walls contain an inner cellulose
layer and an outer gelatinous layer of algin.
Pigmentation: Contains chlorophyll
and
, but the yellow-brown pigment fucoxanthin is dominant, giving them their
characteristic brown color.
Food storage: Food is stored as complex carbohydrates, primarily laminarin and
mannitol.
Reproduction: Asexual reproduction is by pear-shaped, biflagellate zoospores with
two unequal, laterally attached flagella. Sexual reproduction is isogamous,
anisogamous, or oogamous.
Distinguishing feature: Some species have complex body differentiation, including a
holdfast (for attachment), a stipe (stalk), and a frond (blade).

13. CYANOPHYCEAE ( CYANOBACTERIA)
Though historically called "blue-green algae," cyanobacteria are prokaryotes
and are now considered a separate kingdom (Monera) from true, eukaryotic
algae.
Cell structure: Prokaryotic; lacks a true nucleus and membrane-bound
organelles.
Pigmentation: Contains chlorophyll
, but the blue pigment c-phycocyanin and red c-phycoerythrin are dominant.
Food storage: Stores food as cyanophycean starch and protein granules.
Reproduction: Asexual through fragmentation, fission, and spore formation
(akinete, endospore). Sexual reproduction is absent.
Distinguishing feature: Can fix atmospheric nitrogen, which is done in
specialized cells called heterocysts.

14. RHODOPHYCEAE ( RED ALGAE)
These algae are predominantly marine and can live at great depths in the ocean.
Cell structure: Mostly multicellular and eukaryotic, with complex body
organization. They are unique in that they completely lack motile stages (flagella
are absent).
Pigmentation: Dominated by the red pigment r-phycoerythrin, which masks the
chlorophyll
and
.
Food storage: Stores food as floridean starch, a carbohydrate very similar to
glycogen.
Reproduction: Asexual reproduction is by non-motile spores. Sexual reproduction
is oogamous and involves complex post-fertilization changes.
Distinguishing feature: Their red pigment allows them to absorb blue light, which
can penetrate deep water, enabling them to live deeper than many other algae.

15. XANTHOPHYCEAE ( YELLOW - GREEN ALGAE )
This is a small group of heterokonts, most of which live in freshwater habitats.
Cell structure: Mostly unicellular or colonial, though some filamentous and
siphonous forms exist. Cell walls sometimes consist of two overlapping halves.
Pigmentation: Contains chlorophyll
and
(or sometimes
) and excess xanthophylls, giving them a yellow-green color. They lack
chlorophyll
and fucoxanthin.
Food storage: Oil and leucosin are the primary food reserves, not starch.
Reproduction: Asexual reproduction by zoospores, aplanospores, or akinetes is
common. Sexual reproduction is rare, but occurs in some species.
Distinguishing feature: Motile cells, including zoospores, have two unequal
flagella (heterokont).

16. BACILLARIOPHYCEAE ( DIATOMS)
Diatoms are a major group of algae that are a key component of marine and freshwater plankton.
Cell structure: Unicellular and eukaryotic, with a unique, rigid cell wall made of silica. The cell wall, called a frustule,
consists of two overlapping halves that fit together like a box and its lid.
Pigmentation: Possess chlorophyll
and
, but their golden-brown color comes from the dominant xanthophyll pigments, including fucoxanthin.
Food storage: Reserve food is stored as oil droplets and chrysolaminarin.
Reproduction: Primarily reproduces asexually by cell division. Sexual reproduction is anisogamous or oogamous and
involves the formation of auxospores to restore normal cell size.
Distinguishing feature: Their highly ornamented and silicified cell walls give them a variety of shapes, and their fossils
(diatomaceous earth) have many commercial applications. (Diatoms)
Diatoms are a major group of algae that are a key component of marine and freshwater plankton.
Cell structure: Unicellular and eukaryotic, with a unique, rigid cell wall made of silica. The cell wall, called a frustule,
consists of two overlapping halves that fit together like a box and its lid.
Pigmentation: Possess chlorophyll
and
, but their golden-brown color comes from the dominant xanthophyll pigments, including fucoxanthin.
Food storage: Reserve food is stored as oil droplets and chrysolaminarin.
Reproduction: Primarily reproduces asexually by cell division. Sexual reproduction is anisogamous or oogamous and
involves the formation of auxospores to restore normal cell size.
Distinguishing feature: Their highly ornamented and silicified cell walls give them a variety of shapes, and their fossils
(diatomaceous earth) have many commercial applications.

17. Thank you