Scientists have modeled the conditions in cold gas-dust clouds, which are the building material for the origin of planetary systems. They found that carboxylic acids involved in the most important system of biochemical processes on Earth, the Krebs cycle, can be formed there.
Nebula recreation experiment
All the basic chemicals involved in the most important biochemical process, the Krebs cycle, can be formed directly in space. This is the conclusion reached by scientists from the University of Hawaii at Manoa.
In their experiment, they took the simplest gases that have long been known to exist in interstellar space: hydrogen, carbon dioxide, ammonia, and oxygen, and cooled them to near absolute zero. After that, the researchers began bombarding them with high-energy particles.
In this way, they recreated dense and cold interstellar clouds. The embryos of stars and their planetary systems are born in them. To make this process finally similar to the conditions of the stellar cradle, the whole volume with gas began to be slowly heated.
The Krebs cycle
The result of the experiment turned out to be extremely interesting. Scientists have proved that if such a process lasts at least a few million years, then as a result of it the cloud will be enriched with all the basic substances from which the cells of living organisms are formed, in particular, carboxylic acids.
Carboxylic acids are a large class of compounds containing a carboxyl group, COOH, and perhaps even more than one. If there are two, the acid is called a dicarboxylic acid, and if there are three, it is called a tricarboxylic acid. The latter are particularly important because they participate in the Krebs cycle.
The Krebs cycle is a ring-closed chain of chemical reactions in which substances, transforming into each other, eventually return to their original state. However, many very important reaction by-products are formed in the process.
The Krebs cycle underlies essential biological processes such as cellular respiration, an aerobic process of energy production. In a sense, it is the first form of life.
Life didn’t originate on Earth
All of the above is extremely important in terms of the debate about the origin of life on Earth. After all, some of what should have formed in the gas-dust cloud over millions of years should then have ended up in the protoplanetary disk. And part of that part is to survive the planet formation phase and be preserved in comets and asteroids. By the way, similar organics have been found there before.
Abiogenesis, that is, the process of the birth of life from inorganic matter by chemical evolution, is in general already fairly well understood. It contains a huge number of small steps, and scientists have long suspected that some of them may have been passed through before the planet itself was formed. A new study suggests that substances already ready for biochemical transformations could have fallen to Earth.
According to phys.org
