The origin of life Lazcano

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Index

1. Introduction

2. Creationism

3. Spontaneous Generation

4. Spallanzani And Needhad

5. Pauster

6. Panspermia

7. The Theory Oparin – Haldane

8. Conditions that allowed life

1. Introduction

Since man had the ability to reason and spite, she was wondering how life arose, giving rise to one of the most complex and difficult problems that has arisen humans, in an effort to find an answer, they attempt explanations fix by religious, mythological and scientific, from these last several theories have emerged and others have been discarded.

This paper based on the play “the origin of life” of the famous author Antonio Lazcano will drive the evolution of the thinking through the years, giving a guideline to better understand this evolution of human thought.

2. Creationism

Since ancient creationist explanations have been posed that a god or more could cause all that exists. From this, many religions began giving creationist explanation of the origin of the world and living beings, on the other hand, science also has some explanations about how living things originated such as the following.

3. Spontaneous Generation

Since ancient times had this thought as acceptable, arguing that life could arise from the mud, water, sea or combinations of the four elements: air, fire, water, and land. Aristotle proposed the spontaneous origin for worms, insects, and fish from substances like dew, sweat and moisture. According to him, this process was the result of interaction of nonliving matter, with forces capable of bringing to life what had not. A call this force the entelechy.

The idea of spontaneous generation of living things, endure for long. In 1667, Johann B, van Helmont, Dutch physician, proposed a recipe that allowed the spontaneous generation of mice: “creatures such as lice, ticks, fleas, and worms, are our guests and neighbors, but born of our guts and excrement. because if we put underwear filled d sudo with wheat in a wide mouth container, after 21 days the odor changes and serious penetrates husks of wheat, changing the wheat into mice. But more remarkable is that these mice are of both sexes and can be crossed with mice that have arisen as normal … ”

Some were unhappy scientist these explanations and began experimenting subjecting all these ideas and theories.

Francisco Redi, an Italian physician, made the first experiments to demonstrate the falsity of spontaneous generation. Achievement demonstrate that worms infesting larvae were meat came from eggs laid by flies in the flesh, just put pieces of meat into three equal containers, the first sealed it, the second covered it with gauze, the third one left uncovered, noted that the worms had covered jar though the meat was rotten and smelly, the second was observed that, over the web, had eggs of flies that could not get through, the flesh of the third bottle had plenty larvae and flies. With this experiment was started to demonstrate the falsity of the theory known as “spontaneous generation”

In the late seventeenth century, Anton van Leeuwenhoek, thanks to the improvement of the optical microscope, achievement discover a hitherto unknown world. Found in dirty water droplets lot of microorganisms that seemed to emerge suddenly with great ease. This finding strengthened the souls of the followers of the “spontaneous generation”

Although the experiments of Redi, the theory of spontaneous generation was not completely rejected, since research of this scientist demonstrated the origin of the flies, but not that of other agencies.

4. Spallanzani And Needhad

At the same time, another scientist named Needhad, contended that a life force that life originated. Their assumptions are based on experiments: boiled beef broth in a bottle, that covered it with a cork, and let stand for several days to observe microscopic sample of the substance, found living organisms. He stated that the heat which had passed the broth was enough to kill any body and that, therefore, the presence of living things was caused by the life force. However Spallanzani was not convinced as many scientist of his day, performing the same experiments Needhad but fully sealed bottles, put to boil, let stand several days and when to observations was not living organisms. This led him to conclude that the organisms found Needhad came by air coming through the cork.

5. Pauster

In 1862, Louis Pauster, French physician, performed a series of experiments aimed at solving the problem of spontaneous generation. He thought that the cause of the putrefaction of organic matter were the organisms that were in the air. To prove his hypothesis, design a swan neck flasks, in which I put nutritious liquid boiled to sterilize them after. Later, I note that in the neck of the flasks were arrested microorganisms air and although this came in contact with the nutrient, no putrefaction of it. To verify his observations, the gooseneck broke a flask, and the liquid contact with air and microorganisms containing the last, there was a breakdown of the nutritional substance Thus was proven by the famous scientist falsity of the theory of spontaneous generation

6. Panspermia

Another proposal to solve the problem of the origin of life, the present Svante Arrhenius in 1908. his theory known as panspermia. According to this, the life came to Earth in the form of spores and bacteria from outer space that au turn, broke off from a planet where there.

This theory can oppose it two arguments:

* Be aware of the conditions of the interstellar medium are unfavorable for the survival of all life. Furthermore, it is known that when a meteor enters the atmosphere, there is a friction that causes heat and combustion destroying any spores or bacteria traveling in them.

* Is that it does not solve the problem of the origin of life, it does not explain how it formed this hypothetical planet in which you would loose the spore or bacteria

7. The Theory Oparin – Haldane

Over the years and having been rejected spontaneous generation theory was proposed physical-chemical origin of life, likewise known as the theory of Oparin – Haldane.

The Oparin-Haldane theory is based on the physical and chemical conditions that existed on the early Earth and that allowed the development of life.

According to this theory, on the primitive Earth existed certain conditions of temperature and Sun radiation affecting substances that then existed in the primitive seas. These substances are combined so that gave rise to living things.

In 1924, biochemist Alexander I. Oparin published “The Origin of Life”, work in suggesting that newly formed Earth and had not yet appeared when the first organisms, the atmosphere was very different from today, according to Oparin, eta early atmosphere lacked free oxygen, but had substances like hydrogen, methane and ammonia. These react with each other due to the energy of solar radiation, electrical activity of the atmosphere and the volcanoes, giving rise to the first living beings.

In 1928, John BSHaldane, English biologist, proposed independently an explanation very similar to Oparin. Such theories, influenced significantly on all scientists concerned with the problem of the origin of life.

8. Conditions that allowed life

For about 5000 million years ago the Earth was formed, along with the rest of the solar system. The materials of cosmic dust and gas surrounding the Sun were merging and solidified to form the planets.

When the Earth condensed, its surface was exposed to sunlight, the clash of meteorites and radiation of elements such as thorium and uranium. This process caused the temperature was very high.

The primitive atmosphere containing water vapor (H2O), methane (CH4), ammonia (NH3), hydrogen cyanide (HCN) and other compounds, which were subjected to heat emitted from volcanoes and ultraviolet radiation from the sun. Another feature of this atmosphere is lacking free oxygen necessary for respiration.

Since at that time was also formed by the ozone layer, which is located in the upper parts of the atmosphere and which serve to filter the passage of the sun’s ultraviolet radiation, these could directly reach the surface of the Earth.

There were also large numbers of cosmic rays from outer space, and electrical activity and radioactive, they were large sources of energy. With the gradual cooling of the earth, the water vapor and rushed condemn the planet in the form of torrential rains, which gave rise to accumulate primitive ocean, whose characteristics define the current.

9. How were the first organisms

The items that were in the primitive atmosphere and seas combined to form compounds such as carbohydrates, proteins and amino acids. As these substances were forming, were accumulating in the seas, and to join microscopic systems formed spheroids delimited by a membrane, which inside had water and dissolved substances.

These types of multicellular systems, we can study from models similar to coacervaros (macromolecules microscopic droplets formed from the mixture of these two solutions are possible precellular model). These are mixtures of complex organic solutions, similar to the proteins and sugars.

Oparin demonstrated that within a coacervate chemical reactions occur that lead to the formation and systems which are becoming increasingly complex. The properties and characteristics do the coacervates presumes that the first systems precelulares much resembled them.

Precelulares systems similar to the coacervates hold an exchange of matter and energy in their surroundings. Such functions also are performed by the current cell through cell membranes.

Because these systems were precelulares exchange with the environment, were becoming increasingly more complex, until the appearance of living beings.

These systems or macromolecules, which call protobionts Oparin, were exposed to adverse conditions sometimes middle, so not all remained on the early Earth, since the differences between each system allowed only the hardiest subsisted, while those who have not succeeded in dissolving the primitive sea, which has been also called primordial soup.

Then, when the protobionts evolved, giving rise to what Oparin EUBIONTES call, already cells and, therefore, had life. According to the theory of Oparin – Haldane and the first living beings arose.

These first living things were simple, but highly developed for its time, it had the capacity to grow by taking environmental substances, and when they reached a certain size are fragmented into smaller ones, which may be called descendants, they retained many features parent.

These offspring would, in turn, grow and subsequently also fragmented, thus beginning the long process of evolution of life on our planet.