To STUDY - Technical - New Dacian's Medicine
Earth - The Evolution of Life (Part I).
Translation Draft
Everything I have presented so far in this section called me „Beginnings” needs to be „connected” with those related to water (posts with which I decided to start because of its importance).
Let’s start, briefly, this way of knowing life by „finding” together the moment of the first multicellular organism!
The first organic „traces”, deposits, in their own right, are found in sedimentary rocks of 4.3 – 4.4 billion years old (only 1-200 million years after the impact with Theia and the formation of the month). Surprised?!? How is that possible?!?
Well, I pointed out that there was no water on Earth because it was far too hot but its atmosphere was composed, besides gas and a real ocean of „air” water, permanently fed by the water that rushed over the earth’s crust and reached fast, hot, in the atmosphere.
This process favored a gradual cooling of the Earth’s crust and, of course, the storage of water from the atmosphere on the Earth’s crust, in direct equilibrium with the decrease of the atmospheric pressure. Scientists have estimated that, initially, atmospheric pressure was around 400 atmospheres, which in time decreased to 2 atmospheres.
Well, this massive pressure drop also had a collateral effect, represented by the fact that it „helped” in the transfer to carbonated minerals of CO2, which were deposited at the bottom of the oceans. These are sediments in which organic traces of fatty acids and sugars have been discovered.
So, it can be deduced from the above that, life „went on the road” faster than anyone expected. It is the period between 4.4 billion years (the Hadrian period of the Precambrian, after the impact with Theia) and 4.2 billion years (the end of the 100 million year period of intense meteoric and the impact remains with Theia) is the moment of the state of incipient life (proto-life).
Then there would be a comparison of the great bombardment with the moment of impact with Theia (Lucifer), whom many consider being a true Armageddon of the Earth. Life could not „pass” this attempt. My view, as you will see below, is that life had passed the test of a „Dante’s Hell” represented by the Earth in formation, as well as it had passed „Theea’s Hell”, and life had overcome any kind of obstacle, such as it will prove later. The earth had once been a liquid magma globe and life found its way. How is that possible?!? Maybe with the help of divine power …
Let’s go back! As you can see in the previous post, during this period (the one after the impact with Theia) came the impact with a comet that brought a lot, a lot of water to the Earth (there may have been water on Theia and there was no need for more this comet), water that „helped” a lot in the development of life, in its form since then, extremophilic (especially thermophilic), unicellular and anaerobic (the water supply brought by the „Great bombardment” is valid).
However, now, the Earth was the „World of Waters”, the waters covering over 90% of its surface. However, the oceans were extremely toxic, with a high salinity content (more than 4 times as much as nowadays) and a particularly high content of metals, so it was not possible to discuss a certain form of life or assimilable to this.
However, one cannot help but notice that the RNA world „evolved” (possibly being) 4.2 billion years ago, in the form of extremophiles. The theories that „try” to explain these „phenomena” are based on some assumptions.
One of these would be the panspermia theory that „states” that life would come from outside our solar system (or from another planet, for example, Mars), either through the remnants of matter carrying spores, organic debris or, something similar (supporting -the finding that many stellar systems are within a radius of 100 light-years from our solar system), or that the transport was mediated by an extraterrestrial intelligence that achieved some kind of insemination of the Earth.
Another hypothesis would be that of the „automatism” of the emergence of life by simply appealing to the chemical elements and their structure, either accidentally or by divine intervention that created the universe by scheduling the compulsory appearance of life.
The whole scientific world joins this last theory, many experiments demonstrating, each to his extent, that from the chemical elements existing at that time, the organic structures that could be at the origins of the evolution of life, as it was then, appeared quickly (where, in particular, the oxidizing agents were missing – all the planets in the solar system have „reducing” atmospheres, rich in CH4, CO2, CO, H2S, NH3 and there is geological evidence that O2 was very rare in the Earth’s atmosphere until 2.2 billion years ago – when assumes (based on geological „testimonies”) that there was some kind of „oxygen” Armageddon that effectively killed most of the anaerobic life forms that existed at that time.
But, from the deductions of scientists, also from these sedimentary deposits, it was necessary that in the period between 4.2 – 3.8 billion years ago, there should be an „RNA world”. From the Earth, it is only the period of initiation of the tectonic plates …
From life, this was a period when the subduction of tectonic plates „transported” the „carbonic” sediments and those of the heavy metals under the earth’s crust, in the mantle, inducing the decrease of the acidity of the oceanic waters existing then, these becoming more and more how much easier it is to manifest life.
Additionally, 4.2 billion years ago, it is estimated that the Earth’s liquid core has stabilized, the convection between it and the mantle layers causing the emergence of a strong magnetic field that protects the earth from solar and cosmic wind radiation and promotes atmospheric retention.
It is considered that, from this moment on, the Earth was ready for the evolution of life, even if the atmosphere of those times did not allow sunlight to reach the earth’s crust or the oceans.
But proto-life has developed in oceans, caves, caves, or the like. It is assumed that the most favorable development areas were those near the underwater volcanic baskets as well as the caves of the geysers.
These areas were permanently receiving various materials, minerals that quickly led to the formation of amino acids, phosphoric acid, nucleated bases (nucleotides) in areas where the water did not exceed 80 – 90 degrees Celsius, thus protecting the new bio-molecule formats.
Then the water circuit intervenes … The protected areas are reductive, the surface areas are oxidative and, thus, there are all the conditions necessary to synthesize bio-molecules.
This water circuit was also greatly amplified by the „approach” of the moon that produced tidal movements immensely larger than those of our times, creating constant cycles of „wet-dry” even at the level of the small ponds or lakes on the nearby land surfaces large accumulations of water.
It is considered that this „wet-dry” cycle was the most crucial factor in the production of life blocks such as fatty acids, ribose, and others.
An important factor was the tendency to accumulate fatty acids which quickly created capsules with different organic elements (especially amino acids), encapsulating them. Here, in this closed environment, under the „wet-dry” cyclicity, the polymerization phenomena have progressed steadily, resulting in the first basic elements of proteins, such as oligopeptides, which acted as catalysts for the subsequent processes of producing bio-molecules from increasingly complex.
In the „proof” of these developments are the experiments of Aleksandr Oparin, Stanley Miller and, Harold Urey who managed to create organic substances (especially amino acids) under the simulated conditions of those times (in a „prebiotic soup” or „primordial soup”). But, let’s go further on the „alley of time”!
Even if there were the „necessary and sufficient” conditions of initiation of life, it seems that the existence of macromolecules was needed. And, it has been scientifically proven (through experiments) that proteins, nucleic acids can polymerize to form macromolecules.
The primordial world, being a world of magma and the Earth’s crust incipient in formation, benefiting from very small „resources” of water, very easily attracted the possibility of situations that favored the synthesis of polymers by dehydration (in an aquatic environment this possibility ” fell ”due to hydrolysis).
And, it was found that a mixture of amino acids spontaneously polymerizes at 130 degrees Celsius, adenylated amino acids polymerize at 60 degrees, and so on.
Also, it has been shown that the addition of CO in such a mixture has the „preference” to make stable peptide linkages between amino acids. Thus it was deduced that a kind of „primordial soup” was dried (on its own) on hot rocks becoming a kind of „primordial pizza” where the necessary polymerization of macromolecules was achieved without problems.
Also, on Earth, there was (and is) Zn (zinc) which is a cofactor of RNA polymerization. And, from the formation of the first RNA elements, it was only a step until the RNA-specific copying processes began (attention, for the unknowing/profane, DNA is a kind of database, a kind of data storage on the hard disk, having not the slightest participation in protein synthesis as RNA has, except for some kind of information site for RNA enzymes regarding the product/reaction coming out of the standard RNA reaction pattern, with the help of nucleic acids from those “primordial soups.” In this sense, Spiegelman and his colleagues have undoubtedly demonstrated that RNA reacts immediately, directly in proportion to the availability of the environment.
And thus, the proto-RNA appeared which was combined with different enzymes, then these „compounds” evolved into ribosomes that could replicate themselves … Remember that all this was done inside the fatty acid capsules ( forming proto-cells), a process quite similar to the actual cells whose membranes are „structurally” formed from lipid double layers.
This would be the state of the „capable” life of reproduction.
OK, now we have macromolecules. And, until the first prokaryotic cell, we need only the isolation made by a membrane. And, scientists have „started” to prove that, the formation of compartmentalized systems may be possible. Not surprisingly, they discovered that phospholipids rapidly form bistratified membranes with „inner” micelles.
This type of membrane is found in most cells and is the most efficient structure that leads to selective permeability and accumulation of specific chemical elements and structures (including organic, amino acids, macromolecules, etc.).
And thus, the mixture of polymers, having a membrane, forms immediately coacervated, the first existential form that can be associated with cells and which is the basis of the theory of abiogenesis (the origin of life without „external” interventions). And, let’s not forget, RNA existed and could self-reproduce. From here, many models have been elaborated to explain the later evolution of life, but they are quite complicated to present here (and to tire you with so much science).
From a kind of spirit of fair play (in a kind of „right to reply”) I can recall the fact that lipids can be synthesized by such „prebiotic formations” but these lipids cannot be used for the „generation” of subsequent lipid rafts, with only some „suggestions” that RNA structures evolved having the ability to „train the internal environment” of such closed systems (especially based on selective permeability properties) to generate such layers in a reparative sense (and later support of the division) and thus solving the problem of the genesis of such elements necessary for the primordial cell membranes.
Interestingly, under these conditions, life has found the way of manifestation towards the exploitation of sunlight, the development of proto-life moving to the second level of manifestation. Thus, a true metabolism has been „developed” that converts light energy into electrochemical energy, using it directly or storing it in saccharides for later use as an energy source in the absence of solar energy.
Thus the leap from volcanic energy, radioactive deposits, etc. to the exploitation of sunlight was achieved. And, importantly, during this period, proto-cell membranes have developed a mechanism to prevent metal ions from oceanic water from entering the interior.
And there was also a mechanism that ensured the evolutionary success of proto-cells represented by the possibility of combining these proto-cells and, indeed, combining them in increasingly complex forms. Think about the fact that current life forms use only 20 types of amino acids to perceive the „strength” of this ability! Indeed, this certifies that these amino acids also existed at the level of these proto-cells, including their „descendants”.
According to the discoveries made, in these proto-cells, the RNA evolved from unstable forms, especially due to ionizing radiation to the forms of RNA with a circular structure, from which it was only a simple evolutionary step to appear the double-stranded DNA structure. acquis.
Yes, you read that right, the first form of manifestation of life was RNA !!! DNA and its metabolism were „detected in sediments” only within the 100 million years following this „keystone” point 3.8 billion years ago.
Thus, the emergence of DNA, a much more stable and much better-structured information storage structure (even if it depends on RNA structures and enzymes), has reached the third stage of proto-life, that of cell emergence. prokaryotes, ancestors of what we now describe as Archaea and Bacteria.
Only 3.5 billion years ago, the first prokaryotic cell (prokaryote microfossils – prokaryotes) is the cells that do not have membrane-protected cell bodies, such as the Golgi apparatus and other complex intracellular structures, which are missing, in particular. nucleoli and the nuclear envelope), this „point” is considered to be the „home” of photosynthesis.
But until the advent of photosynthesis, it took some time. The evolution period of the origins of photosynthesis extends over a long period, between 3.5 and 2.8 billion years ago.
Oxygen, in free form, without „links” to another molecule, is toxic to life because it reduces the reductive capacity of a living organism. This demonstrates, even indirectly, that the first photosynthetic organism was an anaerobic microbe that „avoids” the production of oxygen.
Subsequently, from „additional” energy needs, life was forced to resort to oxygen as a valuable and quite present (oxygen can be easily obtained from the „water reduction” resulting from hydrogen and oxygen) energy source.
The first life forms of „developing” photosynthesis were cyanobacteria. The success of these forms of life is confirmed by the huge deposits of iron oxide that formed during that period, due to the release of oxygen by the forms of life, the planetary ocean being cleaned of iron over time, becoming blue today.
Now, with certainty, the first jellyfish (?!? – a result of the first cellular symbioses) and the first unicellular algae (prokaryotes with anaerobic metabolism) appear and the formation of stromatolite sediments will be discovered which will be discovered today and will attest to these „age” claims. life. „
They continued the evolution, forming massive stromatolite colonies and permanently released oxygen, changing the oxygen composition of the atmosphere to what we know today.
And the life of these stromatolites (something very similar to the coral reefs of today) goes on, as does the evolution of the cells and algae that generated them (stromatolites are sedimentary formations formed by depositing mineral substances, layer by layer, by the forms of life that produce a mineral „residue” of metabolism – thus, generation after generation, this layer becomes thicker and forms a kind of mound (called stromatolite).
And thus, photosynthesis occurs … The first sediments that prove the existence of photosynthesis are certainly dated as being 2.5 billion years old (the end of the pre-Cambrian archaic period – but let’s not forget that it takes time to create sediments and Thus, the emergence of photosynthesis, as we know it today, is placed somewhere 2.8 billion years ago).
This is the moment when geologists confirm the formation of the first continents and the existing forms of life begin to „benefit” from the „support” of the continental shores. This support has given impetus to the development of life forms that are increasingly benefiting from photosynthesis processes, and thus life (especially through the algae from the „coastal” stromatolites) begins to produce more and more oxygen.
But not only the forms of cyanobacteria evolved, but also the prokaryotic cells that specialized as endo-symbiotic systems and thus attracted the specialization of the cellular organisms and the appearance of the nucleus delimiting what would be the eukaryotic cell.
The first organs that formed seem to have been the mitochondria (which still maintain today the „functioning” based on circular RNA) and the chloroplasts that allow energy to be obtained through oxygen (which at that time was usable without problems ).
Another important specialization was the development of an internal membrane (nuclear membrane) to protect the nascent RNA from oxygen. This need for protection was because, by evolution, the need for genetic storage has increased enormously and RNA has been „forced” to „transform” into DNA.
And so, at the beginning of the proterozoic period (2.5 billion years ago) of the Precambrian (which will „last” until 545 million years ago), we reached the first glaciation (Huron glaciation, 2.1 billion years ago, caused by cleaning the atmosphere of greenhouse gases, especially methane) but also at the first fossils large enough and evolved to be considered eukaryotes, 1.7 billion years ago.
Eukaryotes are cells thousands (even millions) times larger than prokaryotes and delimit some kind of crossing over an energy efficiency threshold, which can evolve independently of universal entropy.
Then, 1.2 billion years ago, meiosis and sexual multiplication appeared (although there is clear evidence that it existed in the „RNA world”), which is the moment of a true explosion of multicellular life forms, even though most consisted of colonies of cells of limited complexity.
There are some „interpretations” regarding eukaryotes from those times but it is generally recognized that the most certain eukaryotic structures are at least 900 million years old.
From the studies, it was found that eukaryotes appeared as a result of symbiotic processes (collaboration) between prokaryotes, to facilitate the metabolic processes (endosymbiotic theory) against the background of proto-DNA (at least of circular DNA, the one found in mitochondria). eukaryotes) through the evolution of RNA.
In this sense, the „internal” structure of eukaryotes that „benefit” from most of the internal elements of prokaryotes, the mitochondria, chloroplasts, and flagella are symbiotic in origin.
Moreover, the „development” line starts from Monera (prokaryotes, eubacteria, and archaea) and then separately, as follows: 1. The cyanobacteria (which „take over” photosynthesis) will lead to planta (along with the future protist), 2. paracocci with respiration and thermoplasma with fermentation „enter” into the symbiosis and give rise to the proto-eukaryotic cells (determining mitochondrial symbiosis) to which the spirochetes with „motility” result, resulting in the protist genus, with the first eukaryotic cell and with the microtubular symbiosis (with algae, proteases) others), which ultimately results in 3. fungi and 4. Animalia.
Thus, the horizontal transfer of symbiotic organisms is particularly important for the emergence of eukaryotes. At this „level” RNA and DNA is very similar to the one existing in prokaryotes and many other similarities (it is enough and so – it becomes too scientific to post) …
Eukaryotic unicellular organisms also evolve, benefiting from the experience stored in the DNA of the precursors, complementing the DNA of the descendants. And, life continues its course by developing new symbiotic relationships until, 1.2 billion years ago, the first multicellular organism appeared (jellyfish, sponges, and other similar „stuff”).
This road will go through the great test of the „ice planet”, now 700 (after „other” 600) millions of years, when for ten million years the Earth was an „ice globe”, the period being called the cryogenic ice age. (Cryogenian).
Even if the „white earth” (the ice globe) could be assimilated to the non-existence of life, this „stage” played an essential role in creating the environment most conducive to life … I will detail a little …
The waters of the ocean at that time were more than 4 times saltier than now … Or, the „big iceball” did not form at once and did not disappear at once. At the outset, there were a series of small glaciers that extracted the „fresh” water and deposited it in glaciers, causing a significant increase in the salinity of the ocean waters.
However, the tectonic movements allowed the storage of the remaining salt as a result of the evaporation of the water, deposits that subsequently „entered” the composition of the Earth’s crust, isolating themselves from any contact with the water and, in time, desalinating the oceans.
At the „big thaw” the process was repeated according to the „algorithm” presented above and the salinity decreased even more … And this process continued after a relatively similar mechanism and after this period.
It is only certain that the planetary oceans became much more conducive to „life” through a kind of purification of the aquatic environment that became much more permeable for the circulation of minerals and nutrients so necessary for the development of life.
Continue to the next post …
Love, Gratitude, and Understanding!
Everything I have presented so far in this section called me „Beginnings” needs to be „connected” with those related to water (posts with which I decided to start because of its importance).
Let’s start, briefly, this way of knowing life by „finding” together the moment of the first multicellular organism!
The first organic „traces”, deposits, in their own right, are found in sedimentary rocks of 4.3 – 4.4 billion years old (only 1-200 million years after the impact with Theia and the formation of the month). Surprised?!? How is that possible?!?
Well, I pointed out that there was no water on Earth because it was far too hot but its atmosphere was composed, besides gas and a real ocean of „air” water, permanently fed by the water that rushed over the earth’s crust and reached fast, hot, in the atmosphere.
This process favored a gradual cooling of the Earth’s crust and, of course, the storage of water from the atmosphere on the Earth’s crust, in direct equilibrium with the decrease of the atmospheric pressure. Scientists have estimated that, initially, atmospheric pressure was around 400 atmospheres, which in time decreased to 2 atmospheres.
Well, this massive pressure drop also had a collateral effect, represented by the fact that it „helped” in the transfer to carbonated minerals of CO2, which were deposited at the bottom of the oceans. These are sediments in which organic traces of fatty acids and sugars have been discovered.
So, it can be deduced from the above that, life „went on the road” faster than anyone expected. It is the period between 4.4 billion years (the Hadrian period of the Precambrian, after the impact with Theia) and 4.2 billion years (the end of the 100 million year period of intense meteoric and the impact remains with Theia) is the moment of the state of incipient life (proto-life).
Then there would be a comparison of the great bombardment with the moment of impact with Theia (Lucifer), whom many consider being a true Armageddon of the Earth. Life could not „pass” this attempt. My view, as you will see below, is that life had passed the test of a „Dante’s Hell” represented by the Earth in formation, as well as it had passed „Theea’s Hell”, and life had overcome any kind of obstacle, such as it will prove later. The earth had once been a liquid magma globe and life found its way. How is that possible?!? Maybe with the help of divine power …
Let’s go back! As you can see in the previous post, during this period (the one after the impact with Theia) came the impact with a comet that brought a lot, a lot of water to the Earth (there may have been water on Theia and there was no need for more this comet), water that „helped” a lot in the development of life, in its form since then, extremophilic (especially thermophilic), unicellular and anaerobic (the water supply brought by the „Great bombardment” is valid).
However, now, the Earth was the „World of Waters”, the waters covering over 90% of its surface. However, the oceans were extremely toxic, with a high salinity content (more than 4 times as much as nowadays) and a particularly high content of metals, so it was not possible to discuss a certain form of life or assimilable to this.
However, one cannot help but notice that the RNA world „evolved” (possibly being) 4.2 billion years ago, in the form of extremophiles. The theories that „try” to explain these „phenomena” are based on some assumptions.
One of these would be the panspermia theory that „states” that life would come from outside our solar system (or from another planet, for example, Mars), either through the remnants of matter carrying spores, organic debris or, something similar (supporting -the finding that many stellar systems are within a radius of 100 light-years from our solar system), or that the transport was mediated by an extraterrestrial intelligence that achieved some kind of insemination of the Earth.
Another hypothesis would be that of the „automatism” of the emergence of life by simply appealing to the chemical elements and their structure, either accidentally or by divine intervention that created the universe by scheduling the compulsory appearance of life.
The whole scientific world joins this last theory, many experiments demonstrating, each to his extent, that from the chemical elements existing at that time, the organic structures that could be at the origins of the evolution of life, as it was then, appeared quickly (where, in particular, the oxidizing agents were missing – all the planets in the solar system have „reducing” atmospheres, rich in CH4, CO2, CO, H2S, NH3 and there is geological evidence that O2 was very rare in the Earth’s atmosphere until 2.2 billion years ago – when assumes (based on geological „testimonies”) that there was some kind of „oxygen” Armageddon that effectively killed most of the anaerobic life forms that existed at that time.
But, from the deductions of scientists, also from these sedimentary deposits, it was necessary that in the period between 4.2 – 3.8 billion years ago, there should be an „RNA world”. From the Earth, it is only the period of initiation of the tectonic plates …
From life, this was a period when the subduction of tectonic plates „transported” the „carbonic” sediments and those of the heavy metals under the earth’s crust, in the mantle, inducing the decrease of the acidity of the oceanic waters existing then, these becoming more and more how much easier it is to manifest life.
Additionally, 4.2 billion years ago, it is estimated that the Earth’s liquid core has stabilized, the convection between it and the mantle layers causing the emergence of a strong magnetic field that protects the earth from solar and cosmic wind radiation and promotes atmospheric retention.
It is considered that, from this moment on, the Earth was ready for the evolution of life, even if the atmosphere of those times did not allow sunlight to reach the earth’s crust or the oceans.
But proto-life has developed in oceans, caves, caves, or the like. It is assumed that the most favorable development areas were those near the underwater volcanic baskets as well as the caves of the geysers.
These areas were permanently receiving various materials, minerals that quickly led to the formation of amino acids, phosphoric acid, nucleated bases (nucleotides) in areas where the water did not exceed 80 – 90 degrees Celsius, thus protecting the new bio-molecule formats.
Then the water circuit intervenes … The protected areas are reductive, the surface areas are oxidative and, thus, there are all the conditions necessary to synthesize bio-molecules.
This water circuit was also greatly amplified by the „approach” of the moon that produced tidal movements immensely larger than those of our times, creating constant cycles of „wet-dry” even at the level of the small ponds or lakes on the nearby land surfaces large accumulations of water.
It is considered that this „wet-dry” cycle was the most crucial factor in the production of life blocks such as fatty acids, ribose, and others.
An important factor was the tendency to accumulate fatty acids which quickly created capsules with different organic elements (especially amino acids), encapsulating them. Here, in this closed environment, under the „wet-dry” cyclicity, the polymerization phenomena have progressed steadily, resulting in the first basic elements of proteins, such as oligopeptides, which acted as catalysts for the subsequent processes of producing bio-molecules from increasingly complex.
In the „proof” of these developments are the experiments of Aleksandr Oparin, Stanley Miller and, Harold Urey who managed to create organic substances (especially amino acids) under the simulated conditions of those times (in a „prebiotic soup” or „primordial soup”). But, let’s go further on the „alley of time”!
Even if there were the „necessary and sufficient” conditions of initiation of life, it seems that the existence of macromolecules was needed. And, it has been scientifically proven (through experiments) that proteins, nucleic acids can polymerize to form macromolecules.
The primordial world, being a world of magma and the Earth’s crust incipient in formation, benefiting from very small „resources” of water, very easily attracted the possibility of situations that favored the synthesis of polymers by dehydration (in an aquatic environment this possibility ” fell ”due to hydrolysis).
And, it was found that a mixture of amino acids spontaneously polymerizes at 130 degrees Celsius, adenylated amino acids polymerize at 60 degrees, and so on.
Also, it has been shown that the addition of CO in such a mixture has the „preference” to make stable peptide linkages between amino acids. Thus it was deduced that a kind of „primordial soup” was dried (on its own) on hot rocks becoming a kind of „primordial pizza” where the necessary polymerization of macromolecules was achieved without problems.
Also, on Earth, there was (and is) Zn (zinc) which is a cofactor of RNA polymerization. And, from the formation of the first RNA elements, it was only a step until the RNA-specific copying processes began (attention, for the unknowing/profane, DNA is a kind of database, a kind of data storage on the hard disk, having not the slightest participation in protein synthesis as RNA has, except for some kind of information site for RNA enzymes regarding the product/reaction coming out of the standard RNA reaction pattern, with the help of nucleic acids from those “primordial soups.” In this sense, Spiegelman and his colleagues have undoubtedly demonstrated that RNA reacts immediately, directly in proportion to the availability of the environment.
And thus, the proto-RNA appeared which was combined with different enzymes, then these „compounds” evolved into ribosomes that could replicate themselves … Remember that all this was done inside the fatty acid capsules ( forming proto-cells), a process quite similar to the actual cells whose membranes are „structurally” formed from lipid double layers.
This would be the state of the „capable” life of reproduction.
OK, now we have macromolecules. And, until the first prokaryotic cell, we need only the isolation made by a membrane. And, scientists have „started” to prove that, the formation of compartmentalized systems may be possible. Not surprisingly, they discovered that phospholipids rapidly form bistratified membranes with „inner” micelles.
This type of membrane is found in most cells and is the most efficient structure that leads to selective permeability and accumulation of specific chemical elements and structures (including organic, amino acids, macromolecules, etc.).
And thus, the mixture of polymers, having a membrane, forms immediately coacervated, the first existential form that can be associated with cells and which is the basis of the theory of abiogenesis (the origin of life without „external” interventions). And, let’s not forget, RNA existed and could self-reproduce. From here, many models have been elaborated to explain the later evolution of life, but they are quite complicated to present here (and to tire you with so much science).
From a kind of spirit of fair play (in a kind of „right to reply”) I can recall the fact that lipids can be synthesized by such „prebiotic formations” but these lipids cannot be used for the „generation” of subsequent lipid rafts, with only some „suggestions” that RNA structures evolved having the ability to „train the internal environment” of such closed systems (especially based on selective permeability properties) to generate such layers in a reparative sense (and later support of the division) and thus solving the problem of the genesis of such elements necessary for the primordial cell membranes.
Interestingly, under these conditions, life has found the way of manifestation towards the exploitation of sunlight, the development of proto-life moving to the second level of manifestation. Thus, a true metabolism has been „developed” that converts light energy into electrochemical energy, using it directly or storing it in saccharides for later use as an energy source in the absence of solar energy.
Thus the leap from volcanic energy, radioactive deposits, etc. to the exploitation of sunlight was achieved. And, importantly, during this period, proto-cell membranes have developed a mechanism to prevent metal ions from oceanic water from entering the interior.
And there was also a mechanism that ensured the evolutionary success of proto-cells represented by the possibility of combining these proto-cells and, indeed, combining them in increasingly complex forms. Think about the fact that current life forms use only 20 types of amino acids to perceive the „strength” of this ability! Indeed, this certifies that these amino acids also existed at the level of these proto-cells, including their „descendants”.
According to the discoveries made, in these proto-cells, the RNA evolved from unstable forms, especially due to ionizing radiation to the forms of RNA with a circular structure, from which it was only a simple evolutionary step to appear the double-stranded DNA structure. acquis.
Yes, you read that right, the first form of manifestation of life was RNA !!! DNA and its metabolism were „detected in sediments” only within the 100 million years following this „keystone” point 3.8 billion years ago.
Thus, the emergence of DNA, a much more stable and much better-structured information storage structure (even if it depends on RNA structures and enzymes), has reached the third stage of proto-life, that of cell emergence. prokaryotes, ancestors of what we now describe as Archaea and Bacteria.
Only 3.5 billion years ago, the first prokaryotic cell (prokaryote microfossils – prokaryotes) is the cells that do not have membrane-protected cell bodies, such as the Golgi apparatus and other complex intracellular structures, which are missing, in particular. nucleoli and the nuclear envelope), this „point” is considered to be the „home” of photosynthesis.
But until the advent of photosynthesis, it took some time. The evolution period of the origins of photosynthesis extends over a long period, between 3.5 and 2.8 billion years ago.
Oxygen, in free form, without „links” to another molecule, is toxic to life because it reduces the reductive capacity of a living organism. This demonstrates, even indirectly, that the first photosynthetic organism was an anaerobic microbe that „avoids” the production of oxygen.
Subsequently, from „additional” energy needs, life was forced to resort to oxygen as a valuable and quite present (oxygen can be easily obtained from the „water reduction” resulting from hydrogen and oxygen) energy source.
The first life forms of „developing” photosynthesis were cyanobacteria. The success of these forms of life is confirmed by the huge deposits of iron oxide that formed during that period, due to the release of oxygen by the forms of life, the planetary ocean being cleaned of iron over time, becoming blue today.
Now, with certainty, the first jellyfish (?!? – a result of the first cellular symbioses) and the first unicellular algae (prokaryotes with anaerobic metabolism) appear and the formation of stromatolite sediments will be discovered which will be discovered today and will attest to these „age” claims. life. „
They continued the evolution, forming massive stromatolite colonies and permanently released oxygen, changing the oxygen composition of the atmosphere to what we know today.
And the life of these stromatolites (something very similar to the coral reefs of today) goes on, as does the evolution of the cells and algae that generated them (stromatolites are sedimentary formations formed by depositing mineral substances, layer by layer, by the forms of life that produce a mineral „residue” of metabolism – thus, generation after generation, this layer becomes thicker and forms a kind of mound (called stromatolite).
And thus, photosynthesis occurs … The first sediments that prove the existence of photosynthesis are certainly dated as being 2.5 billion years old (the end of the pre-Cambrian archaic period – but let’s not forget that it takes time to create sediments and Thus, the emergence of photosynthesis, as we know it today, is placed somewhere 2.8 billion years ago).
This is the moment when geologists confirm the formation of the first continents and the existing forms of life begin to „benefit” from the „support” of the continental shores. This support has given impetus to the development of life forms that are increasingly benefiting from photosynthesis processes, and thus life (especially through the algae from the „coastal” stromatolites) begins to produce more and more oxygen.
But not only the forms of cyanobacteria evolved, but also the prokaryotic cells that specialized as endo-symbiotic systems and thus attracted the specialization of the cellular organisms and the appearance of the nucleus delimiting what would be the eukaryotic cell.
The first organs that formed seem to have been the mitochondria (which still maintain today the „functioning” based on circular RNA) and the chloroplasts that allow energy to be obtained through oxygen (which at that time was usable without problems ).
Another important specialization was the development of an internal membrane (nuclear membrane) to protect the nascent RNA from oxygen. This need for protection was because, by evolution, the need for genetic storage has increased enormously and RNA has been „forced” to „transform” into DNA.
And so, at the beginning of the proterozoic period (2.5 billion years ago) of the Precambrian (which will „last” until 545 million years ago), we reached the first glaciation (Huron glaciation, 2.1 billion years ago, caused by cleaning the atmosphere of greenhouse gases, especially methane) but also at the first fossils large enough and evolved to be considered eukaryotes, 1.7 billion years ago.
Eukaryotes are cells thousands (even millions) times larger than prokaryotes and delimit some kind of crossing over an energy efficiency threshold, which can evolve independently of universal entropy.
Then, 1.2 billion years ago, meiosis and sexual multiplication appeared (although there is clear evidence that it existed in the „RNA world”), which is the moment of a true explosion of multicellular life forms, even though most consisted of colonies of cells of limited complexity.
There are some „interpretations” regarding eukaryotes from those times but it is generally recognized that the most certain eukaryotic structures are at least 900 million years old.
From the studies, it was found that eukaryotes appeared as a result of symbiotic processes (collaboration) between prokaryotes, to facilitate the metabolic processes (endosymbiotic theory) against the background of proto-DNA (at least of circular DNA, the one found in mitochondria). eukaryotes) through the evolution of RNA.
In this sense, the „internal” structure of eukaryotes that „benefit” from most of the internal elements of prokaryotes, the mitochondria, chloroplasts, and flagella are symbiotic in origin.
Moreover, the „development” line starts from Monera (prokaryotes, eubacteria, and archaea) and then separately, as follows: 1. The cyanobacteria (which „take over” photosynthesis) will lead to planta (along with the future protist), 2. paracocci with respiration and thermoplasma with fermentation „enter” into the symbiosis and give rise to the proto-eukaryotic cells (determining mitochondrial symbiosis) to which the spirochetes with „motility” result, resulting in the protist genus, with the first eukaryotic cell and with the microtubular symbiosis (with algae, proteases) others), which ultimately results in 3. fungi and 4. Animalia.
Thus, the horizontal transfer of symbiotic organisms is particularly important for the emergence of eukaryotes. At this „level” RNA and DNA is very similar to the one existing in prokaryotes and many other similarities (it is enough and so – it becomes too scientific to post) …
Eukaryotic unicellular organisms also evolve, benefiting from the experience stored in the DNA of the precursors, complementing the DNA of the descendants. And, life continues its course by developing new symbiotic relationships until, 1.2 billion years ago, the first multicellular organism appeared (jellyfish, sponges, and other similar „stuff”).
This road will go through the great test of the „ice planet”, now 700 (after „other” 600) millions of years, when for ten million years the Earth was an „ice globe”, the period being called the cryogenic ice age. (Cryogenian).
Even if the „white earth” (the ice globe) could be assimilated to the non-existence of life, this „stage” played an essential role in creating the environment most conducive to life … I will detail a little …
The waters of the ocean at that time were more than 4 times saltier than now … Or, the „big iceball” did not form at once and did not disappear at once. At the outset, there were a series of small glaciers that extracted the „fresh” water and deposited it in glaciers, causing a significant increase in the salinity of the ocean waters.
However, the tectonic movements allowed the storage of the remaining salt as a result of the evaporation of the water, deposits that subsequently „entered” the composition of the Earth’s crust, isolating themselves from any contact with the water and, in time, desalinating the oceans.
At the „big thaw” the process was repeated according to the „algorithm” presented above and the salinity decreased even more … And this process continued after a relatively similar mechanism and after this period.
It is only certain that the planetary oceans became much more conducive to „life” through a kind of purification of the aquatic environment that became much more permeable for the circulation of minerals and nutrients so necessary for the development of life.
Continue to the next post …
Love, Gratitude, and Understanding!
Dorin, Merticaru