GENETIC CODE AND THE RNA WORLD IN THE EVOLUTION OF CELL.....

Genetic Code And The RNA World In The Evolution Of Cell

   

The RNA world is a hypothetical stage in the evolutionary history of life on earth, in which self replicating or self multiplying RNA molecules proliferate s ( To increase or spread) before the evolution of DNA and proteins.

To fully understand the origin and evolution of cells in present- day living cell, there is a need to consider how they arose in evolution. The most fundamental of this is the expression of hereditary information which requires extraordinary complex machinery and proceeds from DNA to protein through an RNA intermediate. RNA world existed on earth before modern cell arose.

According to this hypothesis, RNA stored both genetic information and catalysed the chemical reactions in the primitive cells. Only later in evolutionary time did DNA take over as the genetic material and protein becomes the major catalyst and structural components of cells. RNA still catalyze several fundamental reactions in modern - day cell which can be regarded as molecular fossils of an earlier world.

The RNA world hypothesis was gradually elaborated and developed, while the mystery ( puzzle) of this stage of the origin of life need more pieces. The fundamental idea of the RNA world was established in the ' 60s and '70s ( Lazcano, 2010), the term ( RNA ) itself originate from the'80s (Gilbert,1986). Till this present day, the RNA world remains of different meaning to the researchers. For some , it only encompasses the pre - cellular stage, i.e. the formation and possible evolution of the macromolecules (RNA and lipids) and surface metabolism. That is , for them RNA world is something not existing ( Not Alive) and very primitive. But for others, the RNA world era includes the appearance of the first cell, which is what we shall be discussing on in the content of this topic. 

  Moreover, ribocell could have achieved quite complex metabolism which is required for translation. Translation is not the sole possibility of employing amino acids or even peptides by the primordial metabolism. Some of the illustration presented below propose that amino acids and / or peptides were employed from an early stages of the RNA world. As long as RNA act as the main information storage and most of the catalysis is done by ribozymes, we are still in the RNA world. The RNA world era has witnessed some of the most fundamental innovations for life, the first living cell among them.

The RNA world had to give rise to the DNA protein world, why? That is because the DNA - protein world is the one we live in, and as a result, this is the final phase which all origin of life scenarios lead to. The discovery of the molecular details of translation led to the formulation of the RNA world Hypothesis, in which the evolution of translation is a rather difficult problem. The path out of the RNA world seems to be very hard . It is if no wonder that the evolution of translation was labeled as a " Notoriously difficult problem" ( crick et al., 1976). Infact, 40 years later it is still an unsolved cluster of questions. That is the RNA world Hypothesis is an unsolved mysteries in the evolution of cell as touching to the origin of life......