All living organisms are divided into precellular and cellular.By precellular include viruses and phages.The second group, the cell is divided into prokaryotes and eukaryotes, which are prenuclear and nuclear organisms.
Prokaryotes
first cell, prokaryotes, appeared on Earth more than 3 billion years ago.It was a great leap in the development of life.Prokaryotes are bacteria.Structure have relatively simple.Genetic information, DNA, is in their primitive, containing little protein ring-chromosome.It is located in a part of the cytoplasm, nucleoid, not separated from the rest of the cell membrane.Main than eukaryotes and prokaryotes differ from each other, it is that the cells of the first type of nucleus is not present.
prenuclear cytoplasm of cells is much smaller cell structures.Of these known ribosome smaller compared with ribosomes eukarioidnyh cells.The role of mitochondria in prokaryotes belong to simple membrane structures.No therein and chloroplast.Prokaryotes are the plasma membrane, which is under the cell membrane.They differ from eukaryotes razmerami.V significantly lower in some cases may be prokaryotes called plasmids - small in the form of a ring, the DNA molecule.
eukaryotes
all nucleated cells differ in the general plan of the building and common origin.They emerged from the cells prenuclear 1.2 billion. Years ago.Their structure is much more complicated.And prokaryotes and eukaryotes are cell membrane.But in the rest of their structural and biochemical characteristics are very different.The most important difference - the fact that there is a real nucleated cells nucleus, which stores its genetic information.
kernel separated from the cytoplasm of a special membrane, consisting of outer and inner layers.It is similar to the plasma membrane, but contains pores.Thanks to them is exchanged between the cytoplasm and the nucleus.Cell genome consists of a set of chromosomes, that prokaryotes and eukaryotes are also different from each other.DNA in the chromosomes of eukaryotes is associated with histone protein.
in the nucleus of cells are nucleoli, which are formed of the ribosome.Structureless mass karyoplasm surrounds the chromosomes and nucleoli.Each type of animal and plant species peculiar to a strictly defined set of chromosomes.During cell division, they doubled and then distributed to the daughter cells
Considering prokaryotes and eukaryotes, the differences they have seen in the cytoplasm of cells.
to plant cells characteristic of the presence of a large central vacuole and plastid.This vacuole can push the core to the periphery of the cell.Nourishing reserve carbohydrate plant cell - starch.Outside plant cells coated with a cell wall composed of cellulose.In the center there is a cellular centrioles, which can be seen only from algae.
Animal cells do not have a central vacuole, plastids and thick cell wall.At the center of the cell there is a centriole.Reserve carbohydrates in animal cells - glycogen.
Cells centriole fungi does not always happen.Cell wall composed of chitin, no plastids in the cytoplasm, but the center cell central vacuole attaching.Reserve carbohydrates in them - too glycogen.
in the cytoplasm of eukaryotes are the mitochondria, Golgi apparatus, lysosomes, endoplasmic reticulum, organelle movement.Ribosomes they are much larger than prokaryotic ribosomes.The cytoplasm of cells is divided into separate compartments, compartments by special membranes composed of lipids.Each flow its biochemical processes.It's almost not found in prokaryotes.
In general, prokaryotes and eukaryotes express the laws of evolution, which is characterized by the move from simpler to more complex forms.
However prenuclear cells characterized by great flexibility and the variety of metabolic processes.Many bacteria may be powered by light or chemical reactions exist in an environment devoid of oxygen (anaerobic bacteria).Because of this they fit into the picture of the modern world.
