addition to 5 realms of nature, there are two superkingdom: prokaryotes and eukaryotes.Therefore, if we consider the taxonomic position of bacteria, it will be as follows:
- Empire Cell.
- superkingdom Nuclear-free.
- kingdom of prokaryotes.
- Subkingdom bacteria.
why these organisms are allocated to a separate taxon?The fact is that bacterial cells are characterized by the presence of certain features, sets the seal on her ability to live and interact with other creatures and man.
Opening bacteria
discovery of bacterial cells was only with the development of technology.Specifically, with the invention in 1695 microscope authorizing magnified 300 times.This was done by Italian Antonio Van Leeuwenhoek.The scientist looked at his invention droplets of contaminated water, and saw that they were just teeming with micro-organisms.He called them animalkuli.
indubitable proof of their existence, and direct participation in the development of various diseases in humans has been made thanks to the experience of Louis Pasteur.
After this discovery have been identified and studied by many pathogens.Development mikrobilogii (the science of micro-organisms) went intensive steps forward.
Specifically, what what are the characteristics of the structure of the bacterial cell, their variety and form, meaning and lifestyle studies section of Microbiology - bacteriology.Currently, it is closely correlated with other sciences: medical microbiology, molecular biology and biochemistry, biophysics, biology and other space.
forms of bacterial cells that are such
are several.
1 .Ball or coccoid structure. are divided into:
- micrococci - very small, solitary representatives;
- diplokokki - the prefix "di" means "two" (ie bacteria collected in pairs);
- tetrakokki - form chetyrehstrukturnye organisms;
- streptococcus - spherical colony of bacteria collected in a single chain;
- sartsiny - form like a pack of 8, 12 or 16 structures;
- Staphylococci - a colony of bacteria in the form of a bunch of grapes.
2. bacillus or rod-shaped bacteria. differ on several criteria.
- shape: correct and incorrect;
- by size: small, medium or large;
- shaped end structures: pointed, rounded, truncate, thickened;
- for grouping and location: single, diplobatsilly, streptobakterii.
3. crimped. are divided into:
- vibrio - slightly curved in a semicircle;
- spirillum - characterized by different amounts of curls.
4. spirochetes. are divided into:
- leptospira - shaped S;
- Borrelia - 12 curls in the structure;
- treponemy - from 12 to 17 curls small size.
obvious that for the bacterial cells characterized by the presence of various forms to adapt to any environmental conditions.
Features of the structural organization
Bacteria knowingly refer to a separate realm of nature.Men were found to be the inner essence, knowledge of the mechanisms and processes of life.Therefore, it became clear that there are some features of the structure of the bacterial cell.
There are a few main parts that are mandatory for every member of this kingdom.
- presence semipermeable cytoplasmic membrane.
- liquid internal environment - the cytoplasm, in which there is genetic material and ribosomes.
also for bacterial cells and characterized by the presence of optional structures.Such as:
- cell wall;
- microcapsule;
- inclusion;
- drinking;
- capsule;
- disputes;
- flagella;
- pericellular mucus.
consider in more detail what the peculiarities of the structure of the bacterial cell.
structure of cells
Outside each bacterium covered with the cytoplasmic membrane.This structure is a three-layer phospholipid-protein organization.It is very similar in structure and composition to the animal cell membrane.When viewed in visible microscope clearly upper and lower layer are darker consist of phospholipids.Middle - proteins that seemed to permeate the entire membrane, so are integral.
The main function of the cytoplasmic membrane - semipermeable and as a result, the selective transport of substances in and out of the cell.Also, it is a barrier provides a normal level of osmotic pressure and turgor of the cell (shape of body).
For bacterial cells characterized by the presence of the cytoplasm - semi-internal environment, which are important elements.Its structure is presented:
- proteins;
- polysaccharides;
- glycogen granules;
- beta-butyric acid;
- volutin.
Individual attention, cell organelles, immersed in the cytoplasm.
ribosomes and nucleoid
As in any eukaryotic cell, bacteria have a genetic apparatus.It is a densely packed into a ball, double-stranded DNA molecule, which is a single chromosome.This structure is not separated from the cytoplasm karyotheca and therefore is not called the nucleus, and the nucleoid.
additional genetic material distributed in the cytoplasm are the structure called a plasmid.They are circular DNA molecules therefore perform additional functions inherited bacterial cells.
ribosomes - tiny structures in large numbers scattered in the cytoplasm.Their nature is represented by RNA molecules.These granules are the material on which we can determine the degree of relationship and systematic position of a specific type of bacteria.Their function - the assembly of protein molecules.
capsule
For bacterial cells characterized by the presence of protective mucous membranes, whose composition is determined polysaccharides or polypeptides.Such structures are called capsules.There are micro and macrocapsules.This structure is not formed in all species, but the vast majority, that is not mandatory.
which protects the capsule from the bacterial cell?Phagocytosis by host antibodies when pathogenic bacteria.Either from drying and exposure to harmful substances, if we talk about other kinds.
mucus and enable
optionally also the structure of bacteria.Mucus, or glycocalyx, on the basis of the chemical is mucoid polysaccharide.It may be formed within the cell and the outer enzymes.Well soluble in water.Purpose: the attachment of bacteria to the substrate - adhesion.
Inclusion - a micro-granules in the cytoplasm of different chemical nature.These may be proteins, amino acids, nucleic acids or polysaccharides.
organelle movement
Features bacterial cells are also manifested in its motion.For this present flagella which can be varying numbers (one to several hundred per cell).The base of each flagellum - the protein flagellin.Thanks to the elastic cuts and rhythmic movements from side to side the bacteria can move in space.Fastened to the cytoplasmic membrane of the flagellum.Location can also vary in different species.
drank
even finer than flagella, a structure involved in:
- attached to the substrate;
- water-salt diet;
- sexual reproduction.
pilin consists of proteins, their number may reach several hundred per cell.
similarity with plant cells
bacterial and plant cells have one distinct similarities - the presence of the cell wall.However, if the plant it is indisputable, the bacteria may not be present in all species, that is related to optional structures.
chemical composition of the bacterial cell wall:
- peptidoglycan murein;
- polysaccharides;
- lipids;
- proteins.
Typically, this structure has a double layer: external and internal.It performs the same functions as the cell wall of plants.It supports and stands for a permanent form of the body and provides mechanical protection.
spore formation
What is the structure of the bacterial cell, we examined in detail.It remains only to mention that the bacteria can survive unfavorable conditions for a long time without losing viability.
they succeed by forming a structure called the dispute.It is not related to reproduction and only protects the bacteria from adverse conditions.The shape of the debate may be different.When restoring normal operating conditions triggered by the dispute and grow into active bacteria.
