The origin of life is an important contemporary scientific topic, but it is also the most basic biological problem that is still poorly understood so far. There have been various hypotheses about the origin of life in history, such as "God created" (that life was created by God or God) and "spontaneous occurrence" (that life, especially simple life, naturally occurred from inanimate matter). Most of these hypotheses are speculative and have been rejected by people. According to the research papers published at the international conference on the origin of life held in recent years, contemporary hypotheses about the origin of life can be divided into two categories: one is chemical evolution theory, and the other is cosmic embryo species theory. Cell totipotency is not the basis of animal cell culture, but the theoretical basis of plant cell culture. The theoretical basis of animal cell culture is cell proliferation.

According to the theory of chemical evolution, life originated from a series of chemical evolution processes from inorganic to organic and from simple to complex under the conditions of primitive earth. According to the theory of cosmic embryo, the first life on earth came from the outer space of the earth, and then it developed on the earth.

Chemical evolution theory

Biological molecules such as nucleic acid and protein are the material basis of life, and the key to the origin of life lies in the origin of these biological substances, that is, on the lifeless primitive earth, due to natural reasons, abiotic substances produce a variety of organic substances and biological molecules through chemical action. Therefore, the origin of life is first of all the origin and early evolution of primitive organic matter. The function of chemical evolution is to create a class of chemical substances, which constitute common "structural units" such as amino acids and sugars, and life substances such as nucleic acids and protein come from this combination of "structural units". 1922, biochemist obalin was the first to put forward a verifiable hypothesis that some inorganic substances on the primitive earth became the first organic molecules under the action of energy from lightning and sunlight. After 3 1 year and 1953, the American chemist Miller first proved this hypothesis. He imitates the atmospheric composition on the primitive earth, and uses hydrogen, methane, ammonia and water vapor to synthesize organic molecular amino acids through heating and spark discharge. After Miller, many experiments were carried out to simulate the primitive earth environment. Other important biomolecules, such as purine, pyrimidine, ribose, deoxyribose, nucleoside, nucleotide, fatty acid, porphyrin and lipid, were also synthesized. 1965 and 198 1 year, insulin and yeast alanine transfer ribonucleic acid were synthesized in China for the first time in the world. Protein and the formation of nucleic acid are the turning point from inanimate to living. The successful synthesis of the above two biomolecules has opened a new era of studying the origin of life through synthetic life. Generally speaking, the chemical evolution of life includes four stages: from small inorganic molecules to small organic molecules; Forming organic macromolecules from small organic molecules; From organic macromolecules, a multi-molecular system that can maintain its own stability and development; From a multi-molecular system to primitive life.

Cosmic embryo species theory

In the past and now, many hypotheses belonging to the theory of cosmic embryo have been put forward. For example, at the 10th International Conference on the Origin of Life in July 1993, it was suggested that "the organic matter that caused the chemical reaction and led to life was brought by a comet that collided with the earth", and it was inferred that one of the comets collided with the earth with the "embryo of life" and passed through the universe, making it just born. A few years ago, a space physicist and an astrophysicist also explained the origin of life on earth as: the source of life on earth may come from one or several comets that fell into the ocean 4 billion years ago. They also believe that comets provide raw materials for the birth of life on earth (they call them "life-like creatures"). Although some scientists strongly oppose this hypothesis (they think that "comets bring some substances, but they are not decisive, and the substances necessary for life already exist on the earth"). Although this view is still some problems that need further proof, through the exploration and research of meteorites, comets, interstellar dust clouds and organic molecules on other planets. Understanding the formation and development of those organic molecules and comparing them with those on the earth will provide more information for the study of the origin of life on the earth.

Gene theory

Genes come from parents and remain unchanged for almost a lifetime, but due to genetic defects, some people are naturally prone to certain diseases, which means that the existence of certain genotypes in the human body will increase the risk of certain diseases. This gene is called the disease susceptibility gene.

As long as we know the susceptibility genes of diseases in the human body, we can infer which diseases people are prone to. However, how can we know which diseases we are prone to? This requires genetic testing.

How is genetic testing carried out? With a special sampling stick, exfoliated cells are scraped from the oral mucosa of the subjects, and with the help of advanced instruments and equipment, researchers can obtain DNA samples from these exfoliated cells. After DNA sequencing and SNP single nucleotide polymorphism detection of these samples, we can clearly know the difference between the subjects and others in gene sequencing. By comparing with the gene samples of many diseases that have been found, we can find out which diseases are prone to in the DNA of the subjects.

Genetic testing is not equal to medical diagnosis of internal diseases. The results of genetic testing can tell you how high the risk of a certain disease is, but it doesn't mean that you already have a certain disease, and it doesn't mean that you will definitely get it in the future.

Through genetic testing, we can provide people with personalized health guidance services, personalized medication guidance services and personalized physical examination guidance services. It is possible to carry out precise prevention years or even decades before the disease occurs, rather than blind health care; People can effectively avoid the environmental factors of diseases by adjusting diet and nutrition, changing lifestyle, increasing the frequency of physical examination and accepting early diagnosis and treatment.

Genetic testing can not only tell us in advance how high the risk of illness is, but also clearly guide us to use drugs correctly and avoid the harm of drugs to us. It will change the situation of indiscriminate medication, ineffective medication, harmful medication and blind health care in traditional passive medical care.

The Significance of Studying the Origin of Life

Studying the origin of life is to find out the history of the birth of life for billions of years. However, its significance goes far beyond tracing the source. It also lies in understanding the bargaining relationship between life and environment, whole and part, structure and function, micro and macro, individual development and system development, matter and energy, and information. We can further clarify the mechanism of life activities such as genetic variation, growth and differentiation, reproduction, metabolism, exercise induction and regulation, so as to understand and clarify the essence of life and realize human control.