From Molecular Replication To Cellular Replication In The RNA World:Modeling The First Major Transition During The Arising Of Life

The RNA world is very attractive to those who have a strong interest in the origin of life.The synthesis of nucleotides has been a hot topic in this field,let alone the replication of ribozymes.In addition,the origin of the protocells is even more attractive.By introducing "Tag mechanism",from a single enzyme replication system to multi-enzyme system and then to the protocell system with amphiphilic molecules.We studied the key factors in these systems.After in-depth studies,we have some new understandings about the "parasite" problem,spatial limitation etc.(1)a single polymerase system,although have strong adaptability about different environment,such as high molecular mobility,higher molecular degradation rate,but the defects are also fatal,single polymerase system is heavily dependent on the natural synthesis of nucleotide in the environment.Actually,the natural synthesis of nucleotides in reality is more difficult,even if there can be a new synthetic pathway but will also be limited to a specific geographical environment(such as the catalytic surface of the rock,etc.).Another question is how does the system spread out and use farther raw materials?(2)The emergence of synthetic enzymes does have solved the problem of nucleotide synthesis in our system.And it also will be the part of trend that the system developed to complexity,efficiency and functional differentiation.However,the flaw is still huge.The cooperation of the two enzymes is very difficult just to rely on the spatial limitation and "Tag mechanism".The multi-enzyme system cannot survival in where the RNA molecule move fast and degrade quickly,it means that the multi-enzyme system is still not good enough;(3)The emergence of protocell system,perfectly solved those obstacles which block the RNA world's development.The cell membrane effectively encapsulates multiple enzymes make them to keep close and collaboration,providing a platform for the development of more functional RNA molecules.At the same time,the ability of the protocells greatly improves the system's ability to diffuse,enabling the system to develop a treasure trove of raw materials that is far away from the original spot.The more active system is the best practice platform for Darwinian evolution.Another great benefit of cell wrapping is resistance to various environments(such as with high degradation rates)that protects RNA molecules from harsh environments.