Life today is always moving forward from life. However, at least once in history it has to emerge from inert matter.
Let’s face it: most of us want to have a family tree that will span many generations, perhaps, to the grandparents of our grandparents. But wouldn’t that be even more amazing? Extend that tree to our most distant ancestors, That is, to the origin of life?
In this article, we will outline some of what is currently known about one of the most exciting topics in science.
What defines life?
The first difficulty in researching the origin of life Definition Features that are important to classify as living must be presented. This question may seem simple when compared to a stone rabbit to take a trivial example. Not so when we move into those distant times when life begins.
Life today is always moving forward from life. However, at least once in history it has to emerge from inert matter. This suggests that it is not surprising that the first forms of life were very similar to the inanimate objects from which they came, which makes them difficult to distinguish.
Defining the essential features of life is also crucial if one is to begin the search for life in other worlds. It is especially familiar with the manifestations of terrestrial life, as it can be presented in a way that is invisible to our eyes.
What does life do?
Life produces its incomplete copies, for that matter Energy and matter exchange with the external environment By chemical reactions. For its proper functioning, some Suggestions, Information that needs to be maintained over time and, therefore, should be passed on to offspring. In addition, a compartment is needed that differentiates the living system from the environment and allows for proper interaction between its components.
The only example of life we know of is the earth, The information is stored in the DNA molecule Laws based on the 4-letter alphabet (four nucleotides: A, T, C, G). They create a collection of different proteins, depending on the order in which they are arranged. These proteins facilitate their own chemical reactions in life. But there is no doubt that things would have been different. They may even be present in other parts of the universe!
When did life on earth begin?
The age of our planet is estimated to be about 4,570 million years (Ma). Initially, their temperature was very high and did not match the stability of the biological molecules. Up to about 3,850 Ma the conditions were stable and favorable for life.
However, they were found Signs of bacterial life in rocks 3,500 m, Raises the problem that there is only a period of about 350 Ma, in which everything has to happen, which facilitates the formation of the first cells. A time when something very complex and amazing seems too small …
To explain the early form of life, theory panspermia, Which maintains that life was created in space between the planets. Even so paseo Microbes throughout the universe seem unlikely, and the discovery of biomaterials in meteorites, comets, and interstellar dust shows that if the object falls in the right place, it will greatly improve life.
The first steps
In the 1920s, Assumptions of Oparin Y Haldane They argued that the first step in the origin of life was the synthesis of biological molecules in the primitive atmosphere using the sun’s ultraviolet light as energy. Those molecules accumulate in shallow lakes or the sea. There they will pave the way for the call together Primordial soup, The basis for the synthesis of more complex molecules that facilitate the formation of cellular life.
This theory was further strengthened in 1953 when Stanley Miller conducted his famous experiment. It did not involve more or less the introduction of a mixture of gases into a chamber, which was believed to create a primitive atmosphere. After supplying power through electrical discharges, the gases reacted and generated many of the basic constituents of organisms, thus proving that their synthesis was possible under agiotic conditions.
Miller is not an experiment And many more later They show that things must inevitably happen that way. They indicate that there is Possible ways of transitioning between chemistry and biology. One of them is 3,800 Ma on our planet.
The world of RNA
In today’s world, functional proteins originate because the information for their synthesis is encoded in DNA. But moving from a sequence of DNA to a protein is a complex process that requires the interaction of other proteins.
The separation of information and activity into two different molecules creates a paradox that can only be solved if we acknowledge that the primitive world resides in the same molecule of information and activity. There is currently ample evidence that RNA may be another nucleic acid similar to this molecular DNA, but with a single chain.
Viroids and RNA viruses show that it can be used to store genetic information. The functional potential of RNA is derived from its ability to fold, causing three-dimensional structures similar to the formation of proteins, which aids in the stimulation of life reactions.
Call “RNA World“A set of molecules capable of storing and transmitting information through their transcripts is assembled, and the catalytic properties of the same molecules facilitate the emergence of a simple metabolism that, once individualized in a compartment, forms the basis of the first cells.
In the aqueous medium, fatty acid molecules can form vesicles, which are shaped like a normal cell. There is something unusual Vesicles capable of incorporating RNA molecules capable of stimulating certain simple metabolic chains. They split! This is not life yet, but it is starting to look like that.
RNA replication is not seen to be added to vesicles. Also, one of the most important is that some of them gain an advantage over the rest. At that moment natural selection will begin to work, as well as all the processes that led to the increase in biological complexity and diversity.
How many failed attempts were made to reach the first cells? We do not know. What we described should not be a one-off event. But what is clear is that the power of natural selection, coupled with random environmental events, led to the survival of a species, the universal ancestor that unites all living things on earth. (I)