prokaryotic cells - is, in fact, just arranged the body, which retains the features of ancestors.They systematically isolated in a separate kingdom Monera, which includes bacteria and cyanobacteria (blue-green algae).
What is so "simple" in the structure of pre-nuclear organisms?Prokaryotic cell has no nucleus, surrounded by their own shell, mitochondria and plastids.In the center of the cytoplasm is nucleoid (nucleotide), which consists of one nukleproteidnoy structure containing circular DNA molecule.This complex is called the bacterial chromosome.The very cells of bacteria and blue-green algae is separated from the external medium thick cell wall or capsule and mucous membrane.The wall of the elementary structural unit consists mainly of a substance murein (formed by proteins and carbohydrates), which performs the function of external skeleton, giving the shape of the cell and protecting it from external irritants.The inner membrane has the following functions: protection, transportation, perception of stimuli and demarcation.
internal structure of prokaryotic cells suggests that the cytoplasm and its composition is much poorer than that of the nuclear (eukaryotic).It contains ribosomes, which are necessary for protein synthesis.There is also a membrane structure, which act as the missing organelles - mitochondria, endoplasmic reticulum, Golgi apparatus and plastids.For example, the prokaryotic cell has a protrusion of the membrane, which is called mesosoma.It is here that the process of respiration and release of energy in bacteria.
also pre-nuclear organisms are capable of sporulation, but they do not breed with them.Disputes or cysts are dense membranes that help the bacteria survive the unfavorable conditions for them.To maintain life in unusual conditions they are able to accumulate nutrients - fats, complex carbohydrates.
prokaryotic cells can multiply by division, budding, and conjugation.The method of reproduction depends on the type of bacteria or cyanobacteria.The division and budding - methods that allow relatively quickly increase the size of the population.Conjugation, which is found in E. coli, is a sexual process, which contributes to the hereditary variation in microorganisms.
Thus, prokaryotes - a pre-nuclear cells, which do not have formalized the cell nucleus and membrane organelles are deprived of many, but can be changed.That they were able to adapt to life in an environment in which no one survives - a nuclear reactor, the oil wells.A great number of representatives of the kingdom Monera are pathogenic and can cause a variety of diseases in humans, animals and plants (dysentery, tonsillitis, tuberculosis).Also, some microorganisms live in symbiosis with eukaryotes (symbiogenesis), for example, nitrogen fixing root nodule bacteria that settle on the roots of legumes.
