Modern ideas about the origin of life.

If you analyze all the data that scientists managed to get in the various studies, it is clear that life on earth - amazingly incredible fact.The chances of its occurrence in our universe are negligible.All stages of the emergence of life contained the possibility of an alternative scenario, which resulted in the world would have remained cold cosmic abyss without a hint is not something that the human mind, and even the smallest microbe.Creationists explain such an incredible event divine intervention.However, the existence of God can not be proved or disproved, and modern ideas of the origin of life, like all science as a whole, based on experimental data and theoretical developments, which can be questioned or confirm.

Vitalism

human knowledge are evolving, something similar to the main points of the process described by Darwin.Theories are natural selection and survival of the fittest, managed to withstand the onslaught of the counter-arguments, or adapt, mutate to match them.Hypothesis of the origin of life also passed a long way of development, the completion of which has not even indicated, as new facts are discovered every day, forcing adjust already established views.

Major milestone on this road became vitalism - the theory of spontaneous generation of life permanent.Under its provisions, the mice appeared in old rags, worms - in rotting food debris.Vitalism prevailed over science experiments until Louis Pasteur in 1860, when he proved the impossibility of spontaneous generation of living organisms.The results caused a paradoxical event: they strengthened the belief in the divine origin and forced scientists to look for evidence that they recently denied.Science seeks to explain that the independent origin of life took place, but a very long time, and occurred in stages, taking millions of years.

Synthesis of carbon

situation seemed hopeless until, until in 1864 AMButlerov not made an important discovery.He was able to receive the organic material (carbon), inorganic (in this experiment it was formaldehyde).The data destroyed an imposing wall delineates still living organisms and the world of dead matter.Over time, scientists were able to get other options of organic from inorganic substances.From that moment began to take shape modern views on the origin of life.They absorbed the data not only biology, but physics and cosmology.

consequences of the Big Bang

theories of the origin of life span a vast period: the first prerequisites for the future formation of organisms, scientists are still in the early stages of the birth of the universe.Modern physics counts existence of the world from the Big Bang, when almost all came from nothing.In the rapidly expanding and cooling down of the universe first formed the atoms and molecules, and then they began to unite to form the first generation of stars.They have become a place of formation of most of the elements known to science today.New atoms filled the space after the explosions of stars, and became the basis for next-generation facilities, including our sun.Current data suggest that the first organic compounds could appear in the protoplanetary cloud surrounding new stars.Of these soon formed and the planet.It turns out that the first stages of life on Earth took place before its formation.

Autocatalytic cycles

processes occurring on the blue planet in its "childhood", supported by the substances forming part of its mineral resources and coming from space as meteorites.Hypotheses of the origin of life one of the most important foundations for the emergence of organic matter on Earth called catalysts of chemical reactions, trapped here with fragments of these "newcomers".They have led to the fact that an overwhelming role in the formation of new substances on the planet began to play very fast processes.

next stage - autocatalytic cycles.In such processes produce substances that contribute to an increase in the reaction rate as well as renewable substrate - elements interact.The cycle is thus complete: the processes themselves faster and themselves "prepared food", ie substances which are again reacted again catalyzing themselves and re-forming the substrate, and so on.

Doubts

Modern ideas about the origin of life has long contained contradictory opinions.The stumbling block - chicken and egg problem.What came first: proteins carry out all processes in the cell, or DNA, which determines the structure of these proteins that stores all the hereditary information.The first essential for the body as it promotes self-maintenance system, without which life is impossible.DNA contains a record structure of cells, also defines viability.The opinions of scientists and the answer to the question was not until the moment when it became known that as a repository of genetic information from DNA virus appears not, and RNA, the third class of organic compounds that are normally assigned to the theory of the origin of life only a minor role.

RNA world

gradually began to accumulate facts and in the 80s of the last century, there is evidence that changed ideas about the early stages of the formation of living matter.Were discovered ribozymes, RNA molecules possessing the ability to proteins, in particular, to catalyze the reaction.First life forms thus can occur without the involvement of proteins and DNA.They are a function of information storage, as well as all the work is done inside the RNA.Life on Earth is now performed by protoorganisms representing the autocatalytic cycle of self-replicating ribozymes.The theory is called "RNA world".

Coacervates

Today it is difficult to imagine the life of that period, since she did not have one important feature - the shell or the boundaries.In fact, it was a solution containing autocatalytic cycle of RNA.The problem of the lack of borders needed to correct the processes, improvised methods solved.Protoorganisms found shelter near the mineral zeolite having a mesh structure of the crystal lattice.Their surface was able to catalyze the formation of an RNA chain and give them a certain configuration.

Further - more, appear on stage coacervates or water-lipid droplets.Hypothesis of the origin of life as recently as well as modern in many respects based on the theory of AIOparin, who studied the properties of these entities.Coacervates - a drop of solution, encased in fat (lipids).They are characterized by selective permeability of the membrane and the ability to carry out metabolism.Some of them apparently united with chains replicating RNA, including those which catalyze the synthesis of lipids themselves.So new forms of life, overcame the way from doorganizmennogo level to the actual organism.The possibility of such structures has been confirmed more recently: scientists have experimentally confirmed the ability of the RNA combined with calcium ions attached to lipid membranes and regulate their permeability.

Skilled assistants

Origin of life in the next stage is the process of improving the functions of organisms formed.RNA has got the ability to catalyze the synthesis of the amino acid polymers, initially fairly simple.The climax of setting a new mechanism was the ability to synthesize proteins.Education appeared several times to deal effectively with biological processes than ribozymes.

Initially, peptide synthesis has not been ordered.The process is a "hit and miss", leaving the amino acid sequence of the case management in the new chains.Over time, an exact copy was fixed, because that it has contributed to greater stability of the entire system.So there was a genetic code that allows certain proteins to synthesize the necessary functions.

Improvement

honing the ability to synthesize the desired proteins took place gradually.The first step was the emergence of a special type of RNA that can connect amino acids.The next phase was followed by the construction of the formation of peptide molecules via arranged in a certain order grounds.The sequence with the RNA template was set.Correlation of "instructions" informative RNA and protein components of the future engaged in a new type of RNA, called transport.As well as information, and it is to this day - the important part of the peptide synthesis.

DNA

Complication organisms followed the path of further improvement of methods of information storage.It is believed that DNA was originally one of the phases of the life cycle of colonies RNA.She had a more stable structure.Its degree of information was much higher, so after some, quite a long time was the main repository of DNA genetic code.

One of the properties of the new education, not allowing time to put the DNA into the head of the theory of the origin of life - is the inability to take action.It was a kind of payment for enhanced features storage media.All the "work" remained proteins and RNA.

Symbiosis

Modern ideas about the origin of life do not lead to an ancestor of the closed and fenced off from the rest of the body.Scientists are more inclined in favor of the assumption that in the early stages there were similarities community microscopic cells that perform different functions.This symbiosis is not difficult to find in nature today.The simplest example - cyano-bacterial mats, which are at the same time the community of micro-organisms and a single whole living being.

emergence of life on Earth biology at the present stage of development sees the process is characterized not by a constant struggle and competition, but rather the ever-increasing certain rallying disparate structures, eventually led to the emergence of a living cell, as we present it today.

generalization

summary, briefly enumerate all the stages of the formation of life, provided as part of the modern theories of the most likely version of the emergence and development of organisms on Earth:

1. Education primary organic compounds in the protoplanetary cloud.

2. gradually come to the fore reactions with the ability to self-acceleration and autocatalytic cycles.

3. emergence of autocatalytic cycles of RNA.

4. Union RNA and lipid membranes.

5. acquisition RNA ability to synthesize protein.

6. emergence of DNA and its adoption as the main repository of information.

7. Education first single-celled organisms through symbiosis.

Understanding the processes that led to the emergence of life, still imperfect.Scientists still a lot of questions.It is not known exactly how RNA arose, many intermediate phases are only theoretical.However, every day put new experiments, checked facts and hypotheses.It's safe to say that our age has given the world a lot more discoveries related to the prehistoric era.