Theories on the Origin of Living Things

1. Controversy between biogenicists and abiogenists.
The first theory about the origin of life is that of spontaneous generation, which states that: life could arise from mud, rotting matter, sea water, dew and garbage. This theory managed to stand for many years, since it was supported by Aristotle and by the Church, the latter with a variant called vitalism that he maintained: the presence of a vital force, a divine breath or a spirit is necessary, capable of giving life to matter inert. Some time later, incredulous scientists try to refute the theory of spontaneous generation and Francisco Redi succeeds using pieces of meat, but shortly after Needham boiling nutritious broths for a short time, he again tries to prove the theory of spontaneous generation and with his experiment he He achieves. But in the same century Spallanzani refutes Needham's experiment by boiling the broths, however this was not accepted by the church considering that the broths were excessively boiled.
Worried about trying to solve the problem, the French academy of sciences summons a contest offering a prize to the one who refutes or really proves the theory of the generation spontaneous. And Louis Pasteur manages to refute it with his experiment that consisted of boiling (he even killed the microorganisms) the broth contained in long-necked S-shaped flasks bent horizontally. And as time passed and the flasks were not infested with microorganisms, it was found that these were in the air by finding the necks of the flasks full of microbes.

2. Theory of the chemical origin of life formulated by Oparin-Haldane.
About 3.5 billion years ago, the physical and chemical conditions of the Earth were very different from today: the The atmosphere lacked free oxygen, so it was strongly reducing, it consisted of hydrogen, methane, ammonia and Water. There was a moderate temperature with very hot areas in the vicinity of the volcanoes and thermal springs; the oceans and lakes had a basic pH; in addition, there were high-energy radiation from outer space. Under these conditions, some simple molecule chemical compounds combined to give rise to more complex ones. This process is known as chemical evolution. The chemical reactions proposed by Oparín to give rise to biomolecules probably occurred and mixed the organic products of those reactions. The sea, shallow lagoons and puddles became primitive broths where molecules collided, reacted and grouped, giving rise to new molecules and molecular aggregates of different sizes and complexity. The intermolecular attractive forces were of great importance in these reactions.

3. Characteristics of the primitive earth and synthesis of organic molecules.
The Earth was acquiring its shape through millions of years. The crust and the primitive atmosphere were formed of light materials located in the outer part. Volcanic eruptions poured lava from hot inland regions, increasing the material in the crust. The steam from the volcanoes, condensed and fell in the form of rain to form the oceans.
The atmosphere of the Primitive Earth probably consisted of: ammonia and methane or of nitrogen and Carbon Dioxide and with small amounts of hydrogen and water vapor. The gases of the early atmosphere probably contained the elements that we find in living organisms: carbon, hydrogen, oxygen and nitrogen, so that possibly the main molecules were formed from these gases organic.

Origin of prokaryotes.
Precellular systems: The precellular systems according to Oparín are the Coacervates. A coacervate is a group of microscopic droplets that is formed by attraction between molecules. Coacervates can be formed from a mixture of proteins and sugar in water.
First Living Beings. Because prokaryotic cells are the simplest, the most primitive cells on Earth must have been simple prokaryotic cells.
It is very difficult to pinpoint exactly when they first appeared or to know the nature of the first types of organisms. However, some prokaryotes appear to have appeared first than others.
Origin of eukaryotes.
The main current theory about the origin of eukaryotes is the endosymbiotic theory of Margulis:
It is a way of explaining the origin of eukaryotes. Margulis, suggests that chloroplasts, mitochondria, and flagella are cellular c-rganelles that derived from free-living prokaryotes and that by a process of endosymbiosis formed part of a single cell. To explain the above, he proposes that a great variety of prokaryotes, some aerobes, must have existed in primitive earth. and other photoautotrophic, as well as various forms of them: amoeboid, spherical, spiraled, etc., and that some prokaryote amoeboid swallowed another aerobically respirator but did not digest it, resulting in a cell with mitochondria, chloroplasts or flagella prim