Pengenalan Dunia Algae

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Pengenalan Dunia Algae
Suratman
Jurusan Biologi FMIPA UNS Surakarta
Karakteristik algae
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Alga (tunggal) atau algae (jamak) kadangkala disebut
ganggang atau seaweeds.
Ilmu yang mempelajari alga secara khusus disebut fikologi
atau algologi
Mengandung klorofil (hingga 4 macam klorofil) dan dapat
melangsungkan fotosintesis. Kadang mengandung
pyrenoid. Mereka dapat menghasilkan oxygen sebagai
produk fotosintesis.
Uniselluler dan multiselluler.
Umumnya hidup di tempat yang cukup air..> Life cycle has
motile stage (swimming)
Struktur Algae
Algae berhabitus talus (Thallophyta) ..> akar, batang dan
daun belum berkembang dengan sempurna.
Pada alga makroskopis, kadang-kadang dapat dibedakan
atas alat perlekatan (holdfast/rizoid), batang/tangkai (stipe)
dan helai daun (blade), namun batang dan daun umumnya
menyatu. Thallus juga dilengkapi dengan pelampung
(bladder) untuk menjaga blade dekat permukaan air
Structure of Seaweeds
A thallus can have many specialized structures including :
1. Frond or blade
Flattened, there is no specific upper or lower side to the
blade. Both sides are capable of capturing sunlight for
photosynthesis
2. Holdfast
The structure attaching the thallus to a surface. It is not a root
structure, it does not go into the sedimen. It does not absorb
nutrients
3. Stipe
A stem-like region between the holdfast and blade of some
seaweeds
4. Pneumatocysts (air bladder)
A gas filled float to buoy up the blades near the sunlight
Primary parts of algae
thallus
Composition of cell walls
• Primarily cellulose but some of them consist of pectin
and alginates acid. Chlorophyta (cellulose
and pectin); Phaeophyta (cellulose, pectin, alginates
acid); Rhodophyta (only cellulose).
• May be impregnated with calcium carbonate
in calcareous algae
• Many seaweeds secrete slimy mucilage
(polymers of several sugars) as a cell. Covering : holds
moisture and may prevent desiccation
• Some have a protective cuticle ..> a multilayered protein covering
Seagrasses vs Seaweeds
How are seagrasses
different from
seaweeds?
WHAT ARE SEAGRASSES?
• Seagrasses are plants
that have evolved to live
in sea water.
• They are called
'seagrass' because most
have grassy leaves, but
none is a true grass.
• Have vascular bundles
• Have flowers
CHARACTERISTICS OF
SEAGRASSES
• Well developed horizontal stems called
rhizomes (occur below the substratum).
• Small erect branches of the rhizome—
short shoots. Leaves arise from these
structures or directly from the rhizome.
• Roots develop on the rhizome and on
the lower parts of the short shoots. Serve
as anchorage and uptake of nutrients.
• Leaves-flat have aerenchyma (tissue
with air spaces). Leaves have a thin
cuticle that allows gas and nutrient
diffusion from the surrounding water.
lacunae
WHY ARE SEAGRASSES IMPORTANT?
• Habitats for many species.
Attachment sites for many
epiphytic algae and
invertebrates.
• Food sources for many animals
(birds, turtles, etc).
• Provide protection for young
marine animals.
• Maintain water clarity by trapping
fine sediments and particles.
• Dense growth of seagrass leaves
creates calm conditions by
reducing water movement by
currents and waves.
COMMON SEAGRASSES
Manatee grass
Syringodium filiforme
Turtle grass
Thalassia testudinum
Eelgrass
Zostera marina
FOSSIL HISTORY OF ALGAE
• Dates back to 3.5 billion years
before present.
• First prokoratic unicelluler algae—
Cyanobacteria—photosynthetic,
without any complex organization.
• Cells with complex organization
evolved with nucleus and other
cellular organelles. With the
exception of the cyanobacteria,
algae are eukaryotes—that is, the
insides of their cells are organized
into separate membrane-wrapped
organelles, including a nucleus and
mitochondria.
What is different in land plants?
Green algae
Charophytes
Evolution of number of anatomical, physiological and reproductive adaptations
Plants
Land colonization
What do algae and land plants
share in common?
z Both undergo photosynthesis. Which means
they both contain chlorophyll and they both
can make their own food (autotrophic).
z They have the same life cycle called alternation
of generations.
z Plants and green algae share similarities in cell
division.
z Plants and green algae has similar biochemical
characteristics (same biosynthetic pigment;
same cell wall component; same carbohydrates
storage material)
Algae and plants have the same life cycle
called alternation of generations.
How are algae different with higher
plants?
• Algae lack the roots, stems, leaves, and other structures typical of
true plants. The photosynthetic portion of the alga is a thallus while
the attachment portion comprises hair-like rhizoids (holdfast) ..>
Thallophytes
• Algae do not have vascular tissues..> non vascular plants. No “pipes”
to carry fluids. An alga moves its materials strictly through diffusion
and osmosis.
• Algae do not form embryos within protective coverings. Mostly,
sperm and eggs of algae fuse in the open water and the zygote
develops into a new plant without any protection. For other plant
groups the zygote develops into an embryo within the protection of
the parent plant. For this reason, all other plant groups are termed
Embryophytes.
How are algae different
(continued)
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Reproductive structures: The gametes are
produced within a single cell. There is no jacket
of sterile cells protecting the gametes
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Variations in pigments.
Variations in cell structure ..> unicellular,
colonial and multicellular forms.
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Compare plants to algae
What makes a land plant better
adapted to live on land than Algae?
Has ability to store and regulate water loss
because of waxes and oils found on the plant
called lipids.
‹ The leaves are able to carry out photosynthesis
on land.
‹ In order to provide nutrients to those leaves
plants must be able to transport water and
nutrients to different parts of the plant.
‹ Plants must have roots to take in those water
and nutrients from the ground.
‹ Reproductive strategies, like the ability to
produce seeds, allow plants to live out of water.
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CELLULAR ORGANIZATION OF ALGAE
• Flagella=organs of locomotion.
• Chloroplast=site of
photosynthesis. Thylakoids are
present in the chloroplast. The
pigments are present in the
thylakoids.
• Pyrenoid-structure associated with
chloroplast. Contains RUBP
Carboxylase, proteins and
carbohydrates.
• Eye-spot=part of chloroplast.
Directs the cell towards light.
Reproduksi Algae
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Sistem reproduksi alga tidak dilengkapi
jaringan sel-sel steril yang berfungsi
melindungi sel-sel fertil, sebaliknya semua sel
berpotensi untuk menjadi fertil dan
menghasilkan keturunan. Embrio tidak
dibentuk di dalam suatu jaringan pelindung
khusus yang dihasilkan induk.
Algae dapat bereproduksi secara vegetatif,
seksual dan aseksual
REPRODUCTION OF ALGAE
Sexual-Gametes
Vegetative
Cell divisions/Fragmentation
=part of the filament
breaks off from the rest and
forms a new one.
Asexual Reproduction
Zoospores after losing their flagella,
form new filaments. No sexual fusion.
SEXUAL REPRODUCTION
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ISOGAMY-Both gametes have flagella and
similar in size and morphology.
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ANISOGAMY-Gametes have flagella but are
dissimilar in shape and size. One gamete is
distinctly smaller than the other one.
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OOGAMY-gamete with flagella (sperm) fuses
with a larger, non flagellated gamete (egg).
SEXUAL REPRODUCTION (CONTINUED)
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isogamy = equal - sized motile gametes
anisogamy = motile gametes
equal-sized
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almost
oogamy = Small motile male gamete with
large non motile female gamete
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Life cycle
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Most algae form some sort
of spore
often motile
Algae also have sex,
often a very simple kind of
sex where the algae
themselves act as gametes
Sometimes very
complicated with egg and
sperm-like cells.
Distribution of Seaweeds
• Most species are benthic where it is
attached to the ocean floor
• Benthic seaweeds can be found on
the inner continental shelf, where
they provide food and shelter to the
community of organisms
• Pelagic species are free floating in
the ocean and are driven by currents
• Distribution depends primarily by light
and temperature
Inter-algal competition
intense
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light
space
nutrients
Special adaptations
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Many species with rapid growth (up
to 0.5 m/day)
Toughness: leathery, flexible
Coralline red algae
ƒ CaCO3 cell walls endure waves
pounding
Tolerant of extremes
ƒ Cold/hot
ƒ Dry/wet
ƒ Turbulence/currents/waves
ƒ Shading
Klasifikasi Algae
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Klasifikasi alga tidak semata-mata didasarkan pada
persamaan ciri morfologi, tetapi lebih berdasarkan sifat
pigmentasinya.
Klasifikasi alga cukup beragam, meskipun secara tradisional
kebanyakan hanya didasarkan pada bentuk morfologi sel-sel
reproduksi, jenis pigmen fotosintesis dan jenis cadangan
makanan. Di samping kloroplas, alga juga mengandung
kromoplas (kromatofor) yang berbeda-beda tergantung
divisinya.
Salah satu model klasifikasi alga
Algae
Euglenoids
Create
green and opaque
water problems
in aquariums.
Diflagellates
Major producer in
marine ecosystems
Zooxanthellae;
toxic blooms
(Red tides)
Diatoms
Golden Algae
Brown Algae
Major component of
Ocean’s minute
plankton
Ecological importance
in cooler ocean water
Green Algae
Red Algae
Ecological importance
in tropical ocean
Reef building
Klasifikasi Chapman dan Chapman (1973)
Salah satu model klasifikasi alga yang banyak diikuti. Alga menjadi
sepuluh divisi, yaitu:
ƒ Bacillariophyta
ƒ Chloromonadophyta
ƒ Chrysophyta
ƒ Cryptophyta
ƒ Euglenophyta
ƒ Pyrrophyta
ƒ Xanthophyta
ƒ Chlorophyta
ƒ Phaeophyta
ƒ Rhodophyta
DIVERSITY IN ALGAE MORPHOLOGY
MICROSCOPIC
Unicellular, Colonial and
Filamentous forms.
Unicellular Algae: Dinoflagellates
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Two flagella that spin the cells
Covered by cellulose plates
Most are marine plankton, but they are common in fresh
water habitats as well; their populations are distributed
depending on temperature, salinity, or depth.
Being primary producers make them an important part of
the aquatic food chain.
Can be free living or in a symbiotic relationship with
jellyfish and other organisms that live near coral reefs
Gonyaulax: toxic species that causes red tide (an
overabundance of these – can be as many as 40-60
million per litre of seawater). The toxins produced during a
red tide may make humans ill.
Euglenoids
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The Euglenoids are one of the bestknown groups of flagellates, commonly
found in freshwater especially when it is
rich in organic materials, with a few
marine and endosymbiotic members.
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Many euglenoids have chloroplasts and
produce energy through photosynthesis
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They can move around like an animal
with flagellates.
Multicellular Algae
• Seaweeds are multicellular algae that inhabit
the oceans
• Major groups of macroalgae are mostly
benthic organisms that are divided into three
major groups according to their
photosynthetic pigments:
– green algae (Divisio Chlorophyta)
– red algae (Divisio Rhodophyta)
– brown algae (Divisio Phaeophyta)
Main groups of alga
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Green algae (most freshwater
algae – some marine; 7000
species)
Brown algae (kelps; 2000
species)
Red algae (includes coralline
algae; 6000 species)
Pigmen Fotosintesis Algae
Sistem fotosintesis alga berdasarkan pada klorofil a, namun
secara keseluruhan pigmen kloroplas Chlorophyta,
Rhodophyta dan Phaeophyta berbeda-beda. Klorofil a juga
terdapat pada Bryophyta, Pterydophyta dan tumbuhan
tingkat tinggi, tetapi strukturnya jauh lebih kompleks.
Kloroplas Chlorophyta mengandung klorofil a, b dan
karotenoid, sama dengan Euglenophyta dan tumbuhan
tingkat tinggi.
Kloroplas Rhodophyta mengandung klorofil a dan d.
Kloroplas Phaeophyta mengandung klorofil a dan c.
Each group limited by its
photosynthetic pigments
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Green algae -- limited to
near surface
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Brown algae -- fairly
deep
– Phycobilins capture
GREEN light
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Red algae – capable of
deepest
– Phycoerythrin captures
GREEN light best
Increasing depth
– Chlorophyll captures
BLUE & RED light
Cadangan Makanan
Alga dapat menyimpan cadangan makanan seperti
kebanyakan tumbuhan lain. Cadangan makanan
Chlorophyta berupa pati yang disimpan dalam kloroplas.
Suatu sifat yang sangat unik mengingat semua eukaryota
fotosintetik lain menyimpan cadangan makanan di luar
kloroplas.
Cadangan makanan Rhodophyta berupa pati/tepung
floridean, suatu polimer yang menyerupai gugus
amilopektin pada pati (bukan gugus amilosa) dan mirip
glikogen.
Cadangan makanan Phaeophyta berupa mannitol
(alkohol) dan laminarin, suatu polimer glukosa yang
ikatannya tidak seperti ikatan pada pati.
Economic Importance of Algae
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Algae are primary producers, they are the start of the
food chain. Phytoplankton are responsible for more
than 45% of the Earth's annual primary production.
Seaweeds are used as fertilizers and even food (by
the Japanese, Irish)
Extracts from the cell walls of algae (typically brown
& red algae) provide the polysaccharides agar and
carageenan. These are used as thickening agents in
food, in surgical dressings and in microbial media.
Algae help build reefs. Marine algae supply shelter
for many marine organisms.
Primary producers
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Most are
AUTOTROPHS
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make their own
food
PHOTOSYNTHETIC
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sunlight is essential
Role in providing habitat
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Holdfast communities increase surface area for smaller organisms
Role in providing habitat
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Other surface area
increases
– Epiphytes:
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Surface of stipe
Surface of blades
– Interior of bladders
(salt sac copepods)
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Break-up
turbulence/provide
shelter
Provide shade for
sensitive organisms
What good is it to us?
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Conditioners in:
– Toothpaste
– Ice cream
– Cosmetics
– Agar
– Carrageenan
Food
Dietary supplements
Livestock, fish feed
Fertilizer
More uses….
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chocolate
additive in instant food drinks
emulsifier, to give certain foods a smooth consistency
serves as a binder to keep mixture intact
surgical jellies, demulcents, and anti-acid tablets
checking hepatitis
curing ulcer
natural latex creaming and thickening for rubber
sizing for textiles, toothpastes, and brake fluids
adhesive for paper bags and gummed tapes
coating for food packages and milk containers
ceramic glazes, leather finishes, broiler compounds, battery plate
separators, beet sugar processing, wax and emulsions; and additive in
the preparation of fertilizer and pesticides
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