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Video: Bacterial Cells - Bacterial Cell Structure, Shapes And Tables
Last updated 6 November 2017 at 13:56
Reading time: 3 minutes
Absolutely all living things, with the exception of viruses, on our planet are composed of cells. Bacteria, on the other hand, are a special kingdom, since their cellular structure is significantly different from the structure of cells of plants, animals and fungi.
I think everyone knows from school that bacteria are prokaryotic microorganisms, which indicates the absence of a nucleus in them. Having appeared at the first stage of the origin of life on Earth, they allowed everything that we can see now to develop.
But do not think that being such simple organisms, in our time they do not play any role. On the contrary, they affect many factors, without which the normal functioning of life on our planet is impossible.
- 1 What is missing in bacterial cells?
2 Features of the processes of bacteria
2.1 Similar articles
What is missing in bacterial cells?
As already mentioned above, in the cells of bacteria, first of all, there is no formed nucleus, which is their main distinguishing feature. Therefore, all the genetic information of a cell is concentrated in a nucleoid, which has a rather primitive structure, but, despite this, it can perfectly transmit the gene. information.
And DNA itself just consists of many nucleoids, which are in a certain order. Violation of this order causes the appearance of a mutation, which manifests itself either in the appearance of new signs, or in the loss of existing ones.
Due to their prokaryotic structure, bacterial cells have certain characteristics in the transmission of hereditary information. The cells of animals, fungi and plants have a nucleus, which contains a certain number of chromosomes. Due to the absence of a nucleus, bacteria have only one chromosome, which is more often called circular DNA, because its structure resembles a ring.
The presence of only one chromosome in a cell negates the manifestation of such features as dominance and recessiveness. But on the other hand, it allows you to transfer the hereditary information of their generation to generation without changes, perfectly preserving the genotype.
And since bacteria multiply very intensively (several tens of generations can change per day), scientists can conduct experiments and identify mutations in order to further study the causes of their appearance.
Since a bacterium is a prokaryotic microorganism, bacteria cells always lack many organelles that are inherent in eukaryotic organisms:
- the Golgi apparatus, which helps the cell by accumulating unnecessary substances, and subsequently removes them from the cell;
- plastids, contained only in plant cells, determine their color, and also play a significant role in photosynthesis;
- lysosomes, which have special enzymes and help break down proteins;
- mitochondria provide cells with the necessary energy, and also participate in reproduction;
- endoplasmic reticulum, which ensures the transport of certain substances into the cytoplasm;
- cell center.
It is also worth remembering that bacteria do not have a cell wall, therefore processes such as pinocytosis and phagocytosis cannot proceed.
Features of the processes of bacteria
As a special microorganism, bacteria are adapted to exist in conditions where oxygen may be absent. And the very same breathing in them occurs due to the mesosomes.
It is also very interesting that green organisms are able to photosynthesize in the same way as plants. But it is important to take into account the fact that in plants the process of photosynthesis takes place in chloroplasts, and in bacteria, on membranes.
Reproduction in a bacterial cell occurs in the most primitive way. The matured cell divides in two, they reach maturity after a while, and this process is repeated. In favorable conditions, a change of 70-80 generations can occur per day.
It is important to remember that bacteria, due to their structure, do not have access to such methods of reproduction as mitosis and meiosis. They are inherent only in eukaryotic cells.
It is known that the formation of spores is one of several ways of propagation of fungi and plants. But bacteria also know how to form spores, which is inherent in few of their species. They have this ability in order to survive particularly adverse conditions that can be dangerous to their lives.
There are known species that are able to survive even in space. No living organisms can repeat this.
Bacteria became the progenitors of life on Earth due to their simplicity of structure. But the fact that they exist to this day shows how important they are for the world around us. With their help, people can get as close as possible to the answer to the question of the origin of life on Earth, constantly studying bacteria and learning something new.