Perhaps people who have studied biology will always think about the origin of life in their hearts. What's more, in the 21st century, the era of molecular biology, it is easier for us to think about this vast world, everything is natural, how did the first cell come about? Did the world come before with DNA, RNA or protein? It seems to be a chicken-and-egg question again, but I'm also obsessed with the question, where do people come from? Here I think the greatest scientist in the world is Charles Darwin!
Speaking of humans, animals, plants, bacteria, archaea, fungi, and viruses, some say that because they all have a common genetic material DNA, to put it more carefully, even the purine and pyrimidine chemical structures are exactly the same, but in the world of our visible matter, any complex substance is composed of simple components and slowly transitions more and more complex, undoubtedly from this point of view, viruses are the first to appear, but also the earliest organisms, but whether it is virus structure or cell structure, How exactly do they come about?
In many books, many chemists and biologists and astronomers have mentioned that the earth came into being from the universe, and since then, more than a hundred elements have been produced as we know them today, and then simple atoms and molecules have been formed, and biologists and chemists believe that life originated from these elements, and these claims have been affirmed, but the question of how humans and other organisms are such complex organisms, composed of countless molecules and tend to live in stability, makes people think deeply.
Of course, it still began with the speculation of physical chemists, when the earth was generated, 90% of it was the vast ocean, but since then, the laws of nature have long been silently engraved on this beautiful planet, and relying on the power of nature, the first batch of "inorganic life" has been derived, they are some simple molecules, hidden in this vast ocean, wandering freely, free, such as the synthesis of ammonia by lightning, and the beginning of organic life, far more than nitrogen and hydrogen, and then the synthesis of methane, carbon dioxide, Wait a minute!
But can these substances really collide and combine to produce humans or other living beings? In fact, a long time ago, many chemists and biologists did experiments, putting ammonia, carbon dioxide, methane, oxygen and other substances into reactors, providing all the natural environment when the earth was first created, trying to derive life, and the result must be nothing! We know that the structure of all matter, including life, always tends to be stable in order to survive natural selection, which is the side of Darwinian evolution, and it is also the side of what physicists call entropy, stability is the only way to fight entropy, and entropy means death, if it is unstable, when the atomic chaos of matter or life reaches a certain level, it is disappearance and death.
But today's organisms are complex and arduous, how they remain stable and exist for a long time, if they are really made of atoms colliding or molecules assembled, then tens of billions of years compared to the time it takes for such collisions to evolve is just a white horse, a moment!
However, the good news is that chemists still found a kind of life substance --- amino acids in the reactor, but in the aforementioned marine world, which is renamed "original soup", molecular amino acids appeared, and its formation should be composed of small molecules such as methane and ammonia or carbon dioxide, so the second batch of "organic life" such as amino acids appeared, and their formation relied on natural energy. However, for many years after that, it was believed that amino acids were a characteristic of life, and the discovery of amino acids on Mars would prove that there was life on Mars?
In this way, in the absence of any living beings, the large and small molecule components in the original soup live freely, they seem to have no thoughts, and their main changes rely on natural selection, which is the first step of evolution, due to the countless collisions and combinations of small molecule objects, in a certain time and space, they become stable complex macromolecules, and these macromolecules begin to absorb the small molecule components related to their own composition, and merge them, forming the primitive competition and predation in Darwin's theory of evolution. There are fewer and fewer small molecule substances, more and more large molecule substances, they have never had feelings at all, "the less food, the more fierce the competition", then a strong one was produced from the macromolecule, called RNA, which is composed of the so-called purines and pyrimidines, and it is surprising that it can be replicated and stored for a long time, which is called the so-called longevity molecule, and these advantages make it immediately stand out and become the best in the competition, but there are also opponents like it, Although it cannot exist stably for a long time, it reproduces faster than it, in other words, it can also replicate itself, and the time period of replication is extreme, which creates a strong competition, so that RNA begins to form double strands, forming a stable concept, or burrowing into the pile of amino acids, protecting itself, until by chance, when it replicates, when the iodine group is paired, it accidentally captures thymine, and becomes a stable body, so it evolves from RNA to the so-called DNA, which is the second evolution of lifeAs a result, from that time on, the common ancestors of all our living beings have learned the laws of survival from molecular times.
They learn to adapt to nature, and those macromolecules that do not adapt to nature begin to be eliminated, but when it comes to this, replication is actually a skill that amazes us, they are smart, in order to survive they learn to use some chemical means, began to capture and destroy other small molecules and macromolecules, their building blocks for their own use, in order to escape from natural predators they fled into amino acids These molecules, to avoid all external counter energy, just like today's tiger kills an antelope, but also eats the components of the antelope for their own use, Since then, DNA has enslaved amino acids, that is, proteins, for its own use, it attaches its body to proteins, hides in a droplet, and lies there quietly, but such evolution is far from enough, only once a phospholipid molecule breaks into that droplet and is captured by the enslaved protein binding, and then more and more lipids are fixed on the droplet, gradually encapsulating DNA, and DNA itself has already evolved its own set of code instructions to enslave and regulate proteins. This indirectly controls some other pathways, such as lipids, which form the first primitive cell on Earth, the prokaryotic cell. However, complex structures often require more entropy to fight and more energy to maintain the structure, and some cells are "lazy", discarding most of the original structure, but giving birth to a series of mechanisms to steal other cells, and eventually evolve into viruses, which are said to have most of the functions of cells.
Why the same DNA, after there will be viruses, fungi, humans, plants, and animals, this is the molecular biology DNA of the primary structure and replication errors determined, the order of nucleotides, the mismatch of replication, etc., led to evolution, these are like copying precious books, if many people copy a real book, there are fewer mistakes, if the first person copies the real copy, the second copy the first manuscript, the third copy the second manuscript, The fourth one is also quite insightful to add its own indirect or rewriting, so that if it goes on, there will be more and more mistakes, and things will progress in many directions, with more of their own appearance and plot, and DNA is not the case, here may be a little contradictory to the principle of stability I said earlier, we said that stability is the ultimate magic weapon to adapt to nature and survival, whether it is material or life, but the same is true of DNA. In order to be stable, the modern DNA molecule has developed its own repair system, which is like the invention of printing by us, which has become a milestone of the fourth evolution, but no matter how accurate it is, it is still indispensable for errors, which is a helpless objective law. So when you think about it, it's not a contradiction. However, in this error of replication, the properties of the quantum may determine all this.
I think the evolution of human beings has gone through more than 40 billion years, and it is impossible to say how many evolutions it is, but as eukaryotes, we can be sure that the appearance of the nucleus is in a sense to protect DNA from harm, maybe we will be grateful for evolution as higher organisms now, but don't forget, we are actually just a lifelong enslaved.
DNA as a strong one, its plunder has conquered any living thing in the world, it is undoubtedly the winner of this world, it is mysterious and powerful, its countless evolutions surpass other molecules, through direct or indirect regulation, so that cells with a similar structure to themselves are grouped together, and then maintain the form of living organisms through replication, so as to protect it through this layer of protection Escape from the ocean, flooded every corner of the earth, and humans and land animals are only its parasitic containers on land, and fish are its containers in the sea, The bird is its container in the air, its changes have created countless creatures, its container is colorful and diverse, and the container can die, but it escapes to another reborn container through the ** reproduction of the organism, eternal and eternal, today's evolution is comfortable and comfortable, there is a good book that says, in the past, DNA evolved in order to compete with other macromolecules to survive, and now it evolves in order to survive the container! RNA must be born from DNA at an early age. Because firstly, RNA is simpler than DNA, secondly, it is the bridge between DNA and protein, and thirdly, even modern DNA replication still requires RNA as a primer, which is the famous RNA world hypothesis, but if you think about it, it is true.
This is what I think is the best of the cell, but I never know where people's feelings, memories, and thoughts are, I firmly believe that it is not a simple chemical reaction, and these understandings will be decomposed next time!