2.3. Cellular form of life
A principal distinction of a cellular form of life from virus is that all the components of which interaction ensures reproduction of another similar form are combined in it as in a single structure. It goes without saying that to ensure such internal interaction of cell components there should be a possibility for a cell as a whole to interact with environment. The only what a cell directly needs to exist and reproduce is symmetrical interactions in the course of which it receives from environment the matter and energy maintaining interaction of its components..
The internal mechanism of cell reproduction is development of the virus reproduction mechanism. Inside a cell, there is a basic component of which purposeful information influence on other components leads to construction of another similar component. However, this does not exhaust its functions yet. A component enters into such information interactions with the rest of cell components that direct their interactions to creating a whole complex of cell components. Thus, one can say that this basic cell component acting like a virus in the direction of self-reproduction, organizes reproduction of an environment wherein its own reproduction becomes possible as well.
This basic component of a cell represents a nucleic acid molecule variety, namely, the deoxyribonucleic acid molecule (DNA). Investigation into DNA structure and mechanisms of its interaction with the rest of cell components is a subject for Genetics. It should be merely pointed out that DNA consists of components called nucleotides of which individual groups organize certain stages of the cell reproduction process through participation in various information interactions and, in total, organize the whole process.
The primary coming of a cell into being as a live form happened because it could take place under certain, although hardly probable, situations of virus-to-environment interaction. At some moment, functioning of a certain virus lead to that a molecule of its DNA and objects which it entered into interaction with happened to be inside one capsule. At this, any of them was able to come into being as realization of virus information interaction with other objects. Coincidence of all these circumstances might occur so seldom during the whole history of life development on our planet that only very few cases have probably happened to form cells stable enough to exist and reproduce themselves as a species. In so doing, the stability did not turn out to be complete enough (the law of large numbers was not realized to a sufficient extent) so that in every case, cell reproduction should lead to forming a complete replica of a parent cell. At this point, new cells started appearing; the most stable of them were preserved as a species. This has just served as a basis for a large variety of currently existing live forms to come into being.
An interesting point about a live cell is that it is about a closed environment from the viewpoint of internal information interactions occurring in it. Their number is sufficiently limited that allows studying everyone of them individually and their complete interrelated structure as a whole. This is certainly a separate task, we shall consider but some properties of these interactions important from the viewpoint of their importance development in more complex information processes.
Information interaction of DNA with a cell component goes through intermediate interactions with some other components rather than through direct symmetrical interactions among them. These are several types of ribonucleic acid (RNA) molecules in a cell. While interacting with DNA they acquire properties that in the course of their further interaction with other cell components result in transmitting them some information to be realized directly in the processes of life maintaining and cell reproduction. Thus, the codes through which information is transmitted from DNA do not coincide with the codes used for receiving information. The intermediate step of information interaction may be extended in time and the moment the information is transmitted does not coincide with the time the information is received. Availability of this time interval and information re-encoding create preconditions for information distortions (among those a possibility of its loss too) in the course of its passing over from one object to another. For an object, distortion of information results in decreased expediency of information changes occurring in it in the course of the information realization. As to a cell, this is fraught with failure in general stability of its vital functions and destruction.
With the aim of preserving a cell as a species during a long period of time there should exist a mechanism for protecting information owing to distortions occurring from time to time. Such a mechanism may be of different nature but the most important is that it should be inherent to properties of the information proper to be transmitted.
Information redundancy is such a property. (This is not its single role useful in the course of information interaction.) Redundancy may realize through simple repetition of codes or in a more complicated manner, i.e. through self-restoring codes. Code self-restoration is based on that it is not only codes directly transferring information that participate in its transmission but also supplementary codes by which correctness of basic codes is checked while it is received. If necessary and possible, information is realized in the same way as if the codes were not distorted. Strictly speaking, it is not the codes proper that undergo restoration but the information carried by them is preserved within permissible limits of distortions and losses. Differentiation of codes into basic and supplementary is rather conventional. Genetic studies demonstrate that the same information can be transmitted by different portions of one DNA and should any of them be excluded this will not lead to distortion of DNA functions. A possibility of using the information redundancy property naturally requires that object receiving information should have consistent properties.
The number of nucleotide groups in DNA molecules is larger than that necessary for normal functioning of a cell. At the same time, the share of excess groups grows against the share of basic groups as functions of a self-dependent cell or an organism of which the cell is a component get more complicated. Respectively, the number of codes involved in transmitting information from DNA is larger than actually needed. This seems to be just what provides primary protection of information from distortions and losses during its exchange inside a cell.
One more factor manifests itself in intracellular exchange of information, which should be taken into account for considering this process. It is present in the process of virus interaction with cell components. The cell that a virus gets in is an environment for it. On starting information exchange with cell components the virus changes their interaction in a purposeful manner and by that makes them to create another similar virus. Such interaction results in distortion of internal information interactions in the cell. If information distortions occurring in this case become significant the cell loses its ability to maintain its own existence and disintegrates. A cell is able to fight against some information distortions, it cannot do this against others whereas the third ones may happen to be neutral or even able to facilitate its existence.
Judging by a virus structure based on either DNA or RNA molecule, viruses have several possibilities to interfere in intracellular information exchange. These are either to distort information in the course of its transmission by changing condition of a cellular RNA or to transmit information by entering into direct interaction with certain cell components instead of a corresponding RNA. Another possible option is when a virus DNA molecule interferes in structure a cell DNA molecule and starts sending information primarily distorted.
The factor of purposeful information transmission from one object to another in situation when its realization is found to be expedient for the former and inexpedient for the latter we shall call misinformation.
In general, notions of Information and Misinformation define the same substance but refer to different ethical categories. They correlate with each other just like notions of spy and intelligent agent do. These notions, considered in terms of their conformity to different purposes, transform from one to the other.
Using a live cell as an example, it is possible to analyze one more type of information interactions. In a cell, DNA not only sends information to other cell components but also receives information from them. If the above information as transmitted is called control information, the latter can be defined monitoring information. This information is transmitted by RNAs (the same ones or others participating in transmission of monitoring information). The information received by DNA is realized in it via changing its condition and thus governs formation of control information. As a result, changes in controlling the processes occurring in a cell are realized in accordance with variations in conditions of its existence. In particular, realization of monitoring information may go through a complex of control information interactions of DNA with other cell components realized by them via the process of its self-reproduction just at the moment that a cell as a whole is ready for it.
Monitoring information plays one more important role in ensuring cell existence stability. Interaction of a cell, as an object, with environment results in changing condition of its individual components, and corresponding information comes to DNA. Realization of such information via changing effects of control information interactions makes the cell as a whole to pass to a condition most adequate for its preservation under given conditions of interaction with environment. Every live cell has such abilities within certain limits simply because those that did not have them terminated their existence as a species. Here is realized the well-known Hegel's thesis saying, "Everything existing is reasonable".
Adequate response of a cell to environment condition represents realization of information received from environment. Mechanism of this realization is based on changes in component interactions inside a cell including information interactions. The cell-to-environment information interaction significance consists in purposeful changing of such an exchange running in a direction most advantageous for existence of a cell as a unit or a species as a whole rather than in results of matter-with- energy exchanges.
Every individual component of a cell is extremely unstable. Its existence consists in regular renovation of a major portion of its sub-components involved by it and energy make-up of their interactions. A relative stability is attained through a complex of interactions of all the cell components for matter and energy exchange of which the primary source is interaction of a cell with environment. Coordination of internal interactions related to exchange of matter and energy is attained through a complex of monitoring and control information interactions of which the central component is DNA molecule. It is interesting that among the processes controlled by these information interactions there is a complex of catalytic processes realized by a certain group of cell components, i.e. biocatalysts. As has already been shown above, catalytic process is a process of most primitive information interaction. Thus, we can see that information interaction may have a hierarchic structure which combines together different interactions levels in a coordinated manner.
Even under most ideal conditions of cell-with-environment external interaction (which, in general, does not exist) instability of separate cell components results in instability of their internal interactions, including information ones. Distortion of the latter is especially important because it affects coordination of all other processes due to losing their significance for each other. This, in its turn, affects internal information interactions and starting from a certain moment the process of their distortion becomes irreversible, cell is getting older, loses its ability to ensure existence of its components and dies.
Unicellular organisms as objects of information interaction with environment differ from viruses, first of all, in that the latter are, mainly, a transmitting side whereas unicellular organisms, on the contrary, are a receiving side. In conformity with the above, the apparatus with unicellular organisms intended for interpretation of information codes through which they receive information and realize it in their actions is developed better. (Truly, we, in general, know nothing like that with viruses). The apparatus of information code interpretation available with cells is of unconditioned and direct character. Its unconditioned character means that the identical code combinations are always perceived by a concrete cell as one and the same information realized by the same actions. Direct character of the apparatus action means that the information is realized about immediately. A cell is not able to store an information received for whatever time, no matter how short it is, and to realize it in a while. The steps of information code interpretation and realizing the information received are not practically divided inside a cell.
By way of a simplest example it is possible to cite reception and interpretation of information received from environment by unicellular organisms such as bacteria in the course of their search for nutrition.
For bacteria, the event of receiving nutrition as such is simultaneously an event of receiving information on nutrition availability. This information is realized via changing the length of their single movements (direction is always casual). The more frequent nutrition, the shorter run. Thus, the probability that bacteria will stay in a rich nutrient medium for a time longer than the time they will stay in a poor nutrient medium is getting higher. This is the most primitive manner in which a live form realizes information during its interaction with environment by way of controlling its own actions (control as a choice of actions out of alternative possibilities available).
The apparatus for interpretation of information received by a cell from environment is completely and unambiguously governed by DNA molecule structure (since it is this structure that controls the apparatus construction) and is transmitted from a parent cell to a daughter one through DNA replica. It does not change during the whole life of a cell and is identical with all cells of one species.