Bacteria — cell Structure of the bacteria and the chemical composition, photos

Modern science has made fantastic progress over the last century. However, some mysteries still excite the minds of eminent scholars. In our days and not found the answer to urgent question – how many species of bacteria exist on our huge planet?

Bacteria – organism with a unique internal structure, which is characterized by all of the processes specific to living organisms. The bacterial cell has many amazing features, one of which – a variety of forms. The bacterial cell may have a spherical, rod-shaped, cubic or stellate form. In addition, bacteria are a little bent or form a variety of curls. Form cells plays an important role for the proper functioning of the organism, as it can affect the ability of bacteria to attach to other surfaces, to obtain the necessary substances and move. The minimum cell size is typically 0.5 mm, in exceptional cases, however, the amount of bacteria can reach 5.0 µm.

Structure of bacterial cell

The structure of the cells of any bacteria strictly ordered. Its structure considerably differs from structure of other cells, such as plants and animals. The cells of all bacteria species do not have such items as: a differentiated nucleus, intracellular membranes, mitochondria, lysosomes.

In bacteria there are specific structural components – permanent and non-permanent.

Permanent components include: the plasma membrane (plasmalemma), cell wall, nucleoid, the cytoplasm. Non-permanent structures are: capsule, flagella, plasmid, pili, hairs, fimbriae, spores.

Cytoplasmic membrane

Any bacteria coats the cytoplasmic membrane (plasmalemma), which includes 3 layers. The membrane contains globulins that are responsible for selective transport of various substances into the cell. Plasmalemma also performs the following important functions:

• mechanical – ensures Autonomous functioning of the bacteria and all of the structural elements,
• receptor proteins located in plasmalemma, act as receptors, that is, help the cell to perceive different signals,
• energy – some proteins are responsible for the function of energy transfer.

The disruption of the functioning of plasmolemma leads to the fact that the bacterium is destroyed and perishes.

Cell wall

Structural component inherent only in bacterial cells – cell wall. This is a hard permeable membrane, which acts as an important structural component of the skeleton of the cell. It is located on the external side of the cytoplasmic membrane. Cell wall implements the protection function, and in addition gives the cell constant form. Its surface is covered with numerous disputes which lets in needed substances and removed from the organism the products of disintegration. Protection of internal components from osmotic and mechanical effects is another function of the wall. It plays an indispensable role in control of cell division and distribution of hereditary traits. In its composition contains peptidoglycan, it gives the cell a valuable immunobiological characteristics. The thickness of cell wall ranges from 0.01 to 0.04 µm. With age there is a growth of bacteria and the quantity of the material from which it is built, increases accordingly.

Nucleoid

Nucleoid is the prokaryotes that stores all the genetic information of a bacterial cell. Nucleoid located in the Central part bacteria. In its properties it is equivalent to the core. Nucleoid is one, closed in the ring, the DNA molecule. The molecule length is 1 mm, and the amount of information about 1000 signs. Nucleoid is the main carrier of the material on the properties of bacteria and a major factor in the transmission of these properties to offspring. Nucleoid in the bacterial cell has no nucleus, membrane and core proteins.

Cytoplasm

The cytoplasm – an aqueous solution comprising the following components: minerals, nutrients, proteins, carbohydrates and lipids. The ratio of these substances depends on the age and type of bacteria.

The cytoplasm consists of various structural components: ribosomes, granules and mesosoma.

• Ribosomes are responsible for protein synthesis. Their chemical composition includes RNA molecules and protein.
• Mesosoma involved in sporulation and cell proliferation. Can be in the form of bubbles, loops, rolls.
• Pellets serve as an additional resource of energy for bacterial cells.These items come in many forms. Their composition is represented by the polysaccharides, starch, droplets of fat.

Capsule

Capsule is a soft tissue structure, which is tightly associated with the cell wall. Exploring it under the light microscope, you notice that the capsule envelops the cell and its external borders are clearly delineated contour. In the bacterial cell capsule is a protective barrier from the phages (viruses). Bacteria form a capsule, when the environmental conditions become aggressive. The capsule is composed of mostly polysaccharides, and in certain cases it may contain cellulose, glycoproteins, polypeptides.

The basic functions of the capsule:

• • adhesion of cells in the human body. For example, streptococci clump together with the enamel of the teeth and in Alliance with other microbes provoke caries,
  • protection from adverse environmental conditions, toxic substances, mechanical damage, high level of oxygen,
  • participation in water exchange (to protect the cells from drying out),
  • the creation of additional osmotic barriers.

Capsule forms 2 layers:

• the inner part of the layer of cytoplasm,
• outer – the result of the excretory function of the bacteria.

The classification formed the structural features of capsules. They are:

• normal,
• complex capsules,
• with striated fibrils,
• intermittent capsule.

Some bacteria also form a microcapsule, which is a mucous formation. To identify the microcapsule can only under the electron microscope, since the thickness of this element is 0.2 microns or less.

Flagellums

Most bacteria have surface structures of the cells that provide mobility and movement – flagella. It's long appendages in the form levothyroxine spiral, built from flagellin (contractile protein). The main function of flagella is that they allow bacteria to move in liquid medium in search of more favorable conditions. The number of flagella in the same cell can vary from one to several flagella, the flagella on the entire surface of the cell or only on one of its poles. There are several varieties of bacteria, depending on the number of flagella in them:

• Monotachi – they have only one flagellum.
• Lavatrici – have a certain number of flagella at one end of the bacteria.
• Amparihy is characterized by the presence of flagella at opposite poles.
• Peritricha – flagella located over the entire surface of bacteria, they are characterized by slow and smooth movement.
• Tarihi – flagella are absent.

Make the flagella motor activity, making a rotational movement. If bacteria have no flagella – she is still able to move, or rather glide with the help of mucus on the cell surface.

Plasmids

Plasmids are small mobile DNA molecules separate from chromosomal factors of heredity. These components usually contain the genetic material that increases the immunity of bacteria to antibiotics. Can transfer your properties from one organism to another. Despite all its features, plasmids did not appear as important elements for the life of bacterial cells.

Drinking, villi, fimbriae

These structures are localized on the surfaces of bacteria. Count from two units to several thousand per cell. These structural elements is movable as a bacterial cell, or stationary, because they do not have any impact on the ability to move. Quantitatively, drinking reach several hundred per bacterium. There are pili, which are responsible for food, water-salt metabolism and conjugation (sex) pili.

The villi characteristic of hollow cylindrical form. It is through these structures in the bacteria get viruses. The villi are not considered mandatory components of the bacteria, because without them can be successfully performed, the process of division and growth.

Fimbriae are usually located at one end of the cell. These structures allow the pathogen recorded in the tissues of the body. Some fimbriae are of particular proteins in contact with the receptor endings of the cells. Fimbriae differ from flagella in that they are thicker and shorter and do not implement the function of motion.

Disputes

Disputes will arise in the case of a negative physical or chemical manipulation on the bacteria (as a result of drying or lack of nutrients). They are diverse in size of spores, different cells they can be quite different. Differs also form spores, they are oval or spherical.

By location in the cage disputes are divided into:

• Central is their position in the center, as for example, anthrax sticks,
• subterminale – located on the end of sticks to form the shape of a Mace (the causative agent of gas gangrene).

In a supportive environment the lifecycle of a dispute includes the following steps:

• preparatory stage,
• the activation step,
• the stage of initiation,
• germination stage.

Disputes are particularly survivability, which is achieved through its shell. It is layered and consists mainly of protein. The dispute increased immunity to negative conditionsand external influences is ensured thanks to the squirrels.