Bacillariophyta definition, characteristics, classification, function
What is the Bacillariophyta algae
Bacillariophyta algae
are unicellular or colony-shaped, spread patterns spread in freshwater and
saltwater. Most species swim freely, but some stick to plants or other objects.
The cell wall consists of two layers, or valves, that cover each other. The
general shape of the cell is rectangular until it is round but there are many
variations.
The cell wall consists
of the inner pectin layer and the silica layer (SiO2) on the outside. Silica is
the most widely distributed mineral in the earth and is the principal part of
glass. If the pectin and organic cell content is destroyed, then there is a
translucent silica shell. Valves are adorned with a wide variety of lines,
wrinkles, holes, and other signs so that Bacillariophyceae or also often called
diatoms look very beautiful under a microscope.
Small holes in the impassable
shell allow a connection between protoplasts and the water-containing environment.
Inside the cytoplasm there are one to several plastids, containing a brown-gold
pigment that covers the chlorophyll. Food substances are stored in the form of
oil, and these objects can often be seen in cells like large round droplets.
Diatoms multiply
themselves by the sexual process, but the main way through cell division. The
nucleus, protoplasm, and plastid split to form two protoplasts, each in one of
the valves. The new wall, which is the inner valve, then grows throughout the
respective protoplasts. The child's cells can either split or remain together
in a colony, their cells united by a bergelatin (sarong) sheath.
The number of species
of diatoms is overwhelming (about 16,000). The number that is now alive or
known to have lived in a distant geological time than was anticipated. Mostly
live in seawater, and when these plants die, they fall to the sea floor and,
because they contain silica, the cell walls will not be crushed-destroyed or
permanently sustainable. This large precipitate of material known as diatomic
earth, is found in many parts of the earth's surface. In the United States, the
largest collection of 1,400 feet (or more than fifty meters) is in California
bacillariophyta
General Characteristics of Bacillariophyta
The
general characteristics of Bacillariophyta are as follows:
1. Unisellular or
colonial with cell walls composed by silicates
2. Single-celled,
colony-shaped body shape by forming bilateral symmetry (pennales) and radial
symmetries (centrales)
3. The arrangement of
cells there is a cell wall called frustula composed of the base called hypoteka
and the cap (epiteka) and belt (singulum). Frustulaini is composed of
pectinyang coated silicon. Epiteka and hypoteka are composed by the upper valve
and the lower valve. Valve is composed of: rafe, stria, central nodulus and
polar nodules. Pennales, pina means fins, strianya composed pinnate, found
mostly in fresh water. Centrales, the stratum is centered, found mostly in
seawater.
4. Movement of a
flagell contained in sperm.
5. The contents of
single-cell nuclei and diploid nucleus, pigment chlorophyll a and c, beta
carotene and sertaxantofil (fukosantin).
6. Habitat is common in
all water situations, but especially in cold water.
Distribution / habitat
This
Bacillariophyta specification consists of widespread diatoms in freshwater and
seawater, as well as in moist soils. The number of diatoms is very large,
estimated at 16,000 species. Due to the large number, diatom phytoplankton
become an important producer component in marine waters. Diatoms are living
alone and some form colonies. Some live freely on the surface of the water,
some other species live on the substrate.
bacillariophyta
Cell Structure
There is a cell wall
called frustula composed of the base called hypoteka and the cap (epiteka) and
the belt (singulum). This frustula is composed of silicone pectin-treated
substances. Epiteka and Hipoteka are composed by the upper valve and the lower
valve. Valve is composed of: rafe, stria, central nodulus and polar nodules.
Pennales pinna means fins, strianya arranged pinnate, found mostly in fresh
water. Centrales, central means center, its stratum is centered, found mostly
in seawater.
Each cell contains one
nucleus with one or more ribbon-shaped plastids or discs, containing abundant
golden brown pigments. Food substances in the form of droplets of oil. The
shape of the diatom cells extends, coated by a cell wall (shell) consisting of
two interlocking hemispheres. This cell wall is made of pectin and silica
layers. When the diatoms die, the remaining silica shells are translucent. The
shell on a diatom is equipped with a small hole that allows the cell to connect
to the water environment.
bacillariophyta
Reproduction of Bacillariophyta
The breeding of
Bacillariophyta is as follows:
1. Vegetally, with cell
division (asexual)
2. Gametes (sexually)
by forming auxospores, by: Partegonosis, pedogami, isogami conjugation,
anisogami conjugation, autogamy and oogami.
Note: Auxospora
Formation
Stem cells will divide
into 2 child cells, each child's cells will split into 2 daughter cells, the
child's cells gradually decreases. The child's cell gradually grows to form
auxospores.
1. Partogenesis
Stem cells do not
divide only the core that divides by mitosis, beginning from the first mitosis.
Then the nucleus fuses, followed by the second mitosis that eventually the cell
wall is broken and the core is covered with mucus and forms a new wall
(auxospora).
2. Pedogamy (child marriage)
The cell with one nucleus
divides meiosis into two child cells and the child's cells will form 4 nuclei,
the plasma cells separating with each of the two nuclei, the first two nuclei
degenerating. The second two cores hold a merger (child marriage), forming
auxospores.
3. Conjugation
Two adjacent stem cells
intercourse, followed by plasmogamy, followed by synapses and end with
karyogami.
Anisogami conjugation:
one cell with one nucleus dividing by meiosis forms into 4 cores. 2 core
degenerates and 2 cores are functional. 2 functional cores hold another cell
division forming 4 cores consisting of 2 large nuclei and 2 small nuclei. Small
core joined with small nucleus (auxospora).
Isogami conjugation: in
principle the isogamous conjugation process is the same as anisogami. The
difference in the core size of the cleavage results is the same.
4. Oogami
Oogami is performed by
an egg (non motile), a male gamete (motil) that enters the female gamete (egg
cell), divides meiosis and forms anteridium.
5. Autogamy
The nucleus of the cell
divides in mitosis into 2 nuclei, followed by meiotic division forming 4
nuclei, 2 degenerated nuclei and 2 nuclei combine to form auxospores.
bacillariophyta
Classification
Diatoms
(Bacillariophyta only consists of 1 classis namely Bacillariophyceae)
unicellular diatoms are present in various forms. According to the form is
divided into 2 orders:
· Order of Centrales
Diatoms with this form
of radial symmetry live in the sea, is one of the plankton constituents. To
make it easy to float in the water, there are floating tools, which are thorns
or wings, or with intermediate lenders. For sexual breeding, a vegetative cell
conducts a reduction division to form four haploid nuclei. Three of them
perished, leaving only one nucleus to be the egg core and the whole cell is now
an oogonium.
· The Order of Pennnales
Diatoms that have a
body of radial symmetry are usually attached to the aquatic plants. Sexual
proliferation takes place with isogami. Two vegetative cells, then removing
pectin and mucilage, each having a reduction division, and forming 4 haploid
nuclei. But each cell does not come out but only 2 gametes, each gamete has 2
nuclei, one can hold a marriage, while the other undergoes a degeneration.
Selected Examples
Navicula
sp. The body of the navicula consists of two parts, the box and the lid.
Between the box and the lid there is a gap called rafe. Proliferation is
vegetative and generative.
Proliferation
of vegetative by splitting. Each diatom core divides into two, followed by the
division of the cytoplasm into two parts. Next, dinsing the cell of the
navicula splits into a box and a lid. In the tiller cells both the box and the
lid will serve as lids and each will form a new box. Thus the seedling cells
coming from the box will have a smaller size than the child's cells. This event
happened repeatedly.
The
proliferation of generative navicula takes place with conjugation. When the
size of the navicula is not possible to hold more division, the nucleus of the
cell will undergo meiosis and produce gametes. This gamete will then leave the
cell and after conception in the water will produce a zygote. The zygote then
grows into a new navicula cell and forms a new box and lid.
Navicula Classification
Division: Chrysophyta
Class:
Bacillariophyceae
Order: Pennales
Family: Naviculaceae
Genus: Navicula
Species: Navicula
laterostrata
Role for Life
The
role of baccilariophyta for life include:
- as a scrubber,
- as dynamite
insulation,
- as a mixture of
cement,
- as an absorbent of
nitroglycerin in explosives.
In addition to useful
for human life, but that does not mean everything is profitable, the presence
of microalgae in aquatic habitats can contaminate the water. Besides will
result in dirt can also decrease water quality. This is because: a) Algae can
cause unpleasant taste and odor; b) Algae may decrease pH; c) Causes color and
clouding; d) Several types of algae can secrete toxins; e) Can mucus out
causing waterblooms.
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