Among the currently existing organisms, there are some of the accessories that to any realm of nature are constant disputes.So it is creatures called cyanobacteria.Even though the exact name they have.Too many synonyms:
- blue-green algae;
- tsianobionty;
- fikohromovye Monera;
- cyano;
- slizievye algae and others.
It turns out that cyanobacteria - it is quite small, but at the same time such a complex and contradictory body, which requires careful consideration and review of the structure to determine the precise taxonomic affiliation.
history of existence and discovery
Judging from fossils, the history of blue-green algae goes back far into the past, a few million years ago.These findings led to the research scientists paleontologists who analyzed the rocks (portions thereof) of those distant times.
on the surface of the samples were found cyanobacteria, the structure of which was no different from that of modern forms.This indicates a high degree of adaptability of these beings to different environmental conditions, to their extreme endurance and survival.It is clear that for millions of years there was a lot of changes in the temperature and gas composition of the planet.However, there is no impact on the viability of cyan.
in modern cyanobacteria - a single-celled organism, which was opened in conjunction with other forms of bacterial cells.That is Antoni van Leeuwenhoek, Louis Pasteur and other scientists in the XVIII-XIX centuries.
closer scrutiny they were later, with the development of electron microscopy and modernized techniques and research methods.There were peculiarities possessed by cyanobacteria.The structure includes a number of new cells are not found in other creatures, structures.
Classification
question determine their taxonomic affiliation is still open.While it is known only one thing: cyanobacteria - prokaryotes.Proof of this are features such as:
- no nucleus, mitochondria, chloroplasts;
- presence in the cell wall murein;
- molecule-S ribosomes composed cells.
However cyanobacteria - prokaryotes, numbering about 1.5 million species.All of them were classified and grouped in 5 large morphological groups.
- Hrookokkovye.Suffice large group uniting solitary or colonial forms.High concentrations of organisms are held together by a common mucus released by the cell wall of each individual.The shape of this group are rod-shaped and spherical structure.
- Plevrokapsovye.Very similar to the previous forms, but there is a feature in the form of formation beotsitov (more about this phenomenon later).Included here cyanobacteria are the three main classes: Plevrokapsy, Dermokapsy, Miksosartsiny.
- Oksillatorii.The main feature of this group is that all the cells are combined into a common structure called mucic trichome.The division takes place, will not go beyond this thread inside.Ostsillatorii include in its membership exclusively vegetative cells, dividing asexually half.
- Nostokovye.Interesting for its cryophilic.Able to inhabit the open deserts of ice forming on them colored raids.The so-called phenomenon of "ice deserts bloom."The forms of these organisms and filamentous as trichomes, but sexual reproduction, with the help of specialized cells - heterocysts.This could include the following representatives: Annaba, Nostoc, Kalotriksy.
- Stigonemovye.Very similar to the previous group.The main difference in the method of reproduction - they are able to share multiply within a cell.The most popular representative of the association - Fisherelly.
Thus, cyan and classified by morphological criteria, as for the rest there are many questions and it turns out the confusion.Botany and Microbiology, the common denominator in the systematics of cyanobacteria can not yet come.
Habitats
Due to the presence of special devices (heterocysts, beotsitov, unusual tillakoidov, gas vacuoles, the ability to fix atmospheric nitrogen and others) these organisms have settled everywhere.They are able to survive even in the most extreme conditions, in which there is no living organism can not exist.For example, hot springs thermophilic, anaerobic conditions with an atmosphere of hydrogen sulfide, acid medium with a pH of less than 4.
cyanobacteria - a body, quietly survive on sea sand and rocky ledges, ice blocks and hot deserts.Explore and identify the presence of the characteristic can be cyan colored coating, which form their colonies.Color can vary from blue-black to pink and purple.
cyanobacteria are called for, which is often on the surface of normal fresh or salt water, they form a blue-green mucic film.This phenomenon is called "blooms."It can be seen on almost any lake, which starts to grow and turn into swamp.
avilable cells
Cyanobacteria have the usual structure for prokaryotic organisms, but there are some peculiarities.
general plan structure of the cell following:
- cell wall polysaccharides and murein;
- bilipidnogo plasma membrane structure;
- cytoplasm with the free distribution of the genetic material in the form of the DNA molecule;
- tillakoidy performing the function of photosynthesis and contain pigments (chlorophylls, xanthophylls, carotenoids).
special look at the cage on.
Types of specialized structures
is primarily geterotsisty.These structures - not often, but the cells themselves as a part of trichomes (general colonial yarn combined with mucus).They differ when viewed in the microscope by its composition, since their main function - production of the enzyme, allowing to fix molecular nitrogen from the air.Therefore, the pigments in geterotsisty there is little, but a lot of nitrogen.
Secondly, it gormogonii - areas taken out of trichomes.They serve as breeding grounds.
Beotsity - is a kind of daughter cells, the mass is endowed with a single parent.Sometimes their number reaches thousands for a single period of division.It features a capable Dermokapsy other Plevrokapsodievye.
Akinetes - special cells that are dormant and included in the trichomes.They are more massive, rich in polysaccharides of the cell wall.Their role is similar to geterotsisty.
Gas vacuoles - they have all cyanobacteria.The structure of cells initially involves their presence.Their role - taking part in the processes of algal blooms.Another name for such structures - Carboxysome.
Cell inclusions.They are, of course, exists in the plant, and animal and bacterial cells.However, the inclusion of blue-green algae are somewhat different.These include:
- glycogen;
- polyphosphate granules;
- tsianofitsin - a special substance consisting of aspartate, arginine.It serves to accumulate nitrogen, as these inclusions are geterotsisty.
This is what has cyanobacteria.Main parts and specialized cells and organelles - that's what allows tsianeyam carry out photosynthesis, but at the same time to treat bacteria.
Reproduction
This process is not particularly difficult, as the same, some are common bacteria.Cyanobacteria can divide vegetatively, parts trichomes normal cell into two, or to carry out the sexual process.
Often in these processes involving specialized cells geterotsisty, Akinetes, beotsity.
methods of movement
cyanobacteria cell is covered with the outside of the cell wall, and sometimes even a special layer of polysaccharide capable of forming mucic capsule around it.It is because of this feature and the traffic moves cyan.
flagella or cilia no special.The movement can only be done on a hard surface with mucus, short cuts.Some Ostsillatorii have a very unusual way to move - they revolve around its axis at the same time cause the rotation of the whole trichomes.Thus there is a movement on a surface.
ability to nitrogen fixation
this feature has almost every cyanobacteria.This is possible due to the presence of the enzyme nitrogenase, the ability to capture atmospheric nitrogen and convert it into a form digestible compounds.This happens in the structures geterotsisty.Therefore, the types that do not have them, to fix nitrogen from the air can not.
Generally, this process makes it very important cyanobacteria exist for the life of plants.Settling in the soil, flora cyan help absorb bound nitrogen and lead a normal life.
Anaerobic types
Some forms of blue-green algae (eg Ostsillatorii) are able to live in a completely anaerobic conditions, and the atmosphere of hydrogen sulfide.In this case the processing of the compound within the organism, and the result is a molecular sulfur exiting into the environment.
