Bacillariophyta definition, characteristics, classification, function

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.

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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.

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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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