Question

2) The origin of life on our planet can be traced back to an early primordial soup and to the origin of RNA. What is the RNA world? Name of the characteristics of RNA as one of the most flexible molecules that kick-stared complex life. (This is an essay question for Biology 1000, please be sure of your answer and I will rate high).

Answer 1

The RNA world is a hypothetical stage that states that the RNA world is the evolutionary history of life on earth, in which self- replicating RNA molecules proliferated before the evolution of DNA and proteins. Like DNA , RNA can store and replicate genetic information like protei enzymes, RNA enzymes can catalyze chemical reactions that are critical for life. Although RNA is fragile, some ancient RNAs may have evolved the ability to methylate other RNAs to protect them. If the RNA world existed , it was probably followed by an age characterized by the evolution of ribonucleoproteins, which in turn ushered in the era of DNA and longer proteins. DNA has better stability and durability than RNA. RNA based ribosomes as biocatalysts because their greater abundance and diversity of monomers make them more versatile.

The concept of RNA as premordial molecule laid out a possible process by which modern genetic system arisen from a nucleotide based precursor , many of the cofactors essential for enzyme function either from nucleotides or ould have been derived from nucleotides. Scientists proposed that this cofactors comes from fossils of nucleic acids enzymes. Scientists reported detecting for the first time sugar molecules including ribose, in meteriorites suggesting that chemical processes on asteroids can produce some fundamentally essential bio-ingredients important to life, and the supporting the notion of an RNA world prior to a DNA based origin of life on earth, and possibly as well, the notion of panspermia.

The concept of RNA as a primordial molecules can be found in research papers Frans Cric and Leslie Orgel as well as Carl Woese's 1967 book' 'The genetic code' work done by other eminent molecular biologists like Alexander Rich , Albert Szent-Gyorgyi, and Hans Kuhn, among others , further confirmed this hypothesis. RNA has great capability as a genetic molecule , it once had to carry on hereditary process on its own . It now seems certain that RNA was the first molecule of heredity, so it evolved all the essential methods for storing and expressing genetic information before DNA came on to the scene. So scientists suggest that such a world came before a DNA world and as the most flexible molecule that

So we can conclude that RNA remains the major molecule for evolution of life on earth, not DNA . There are some unique characteristics of the RNA which makes it a suitable candidate for being considered as the molecule associated with evolution. So the characteristics are discussed below are:

1. RNA as an enzyme, enzymatic properties are important like as self replicating, amino acid RNA ligation, peptide bond formation, and can exist in stable form even under single-stranded forms.

2. RNA as a regulator, and RNA is self- splicing in nature and does not require any other enzymes for its architectural remodeling.

3. RNA represents as a store house of genetic information as well.

4. RNA can catalyze the rate of reactions, such as ribozymes.

5. As a cofactor of many complex bio- molecules ribosomal complex, and hence serves as self- stabilizing.

6. RNA alone can serve as a genetic material in a cell even absence of DNA.

Another important aspect about RNA is RNA synthesis may be driven by temperature gradients, in the process of thermosynthesis. RNA plays an important role in other cellular catalytic reactions, specifically in the targetting of other enzymes to specif RNA sequences. In eukaryotes , the processing of pre-mRNA and RNA editing takes at sites determined by the base pairing between the target RNA and constituents of small nuclear ribonucleoproteins. Such enzyme targetting is also responsible for the gene down regulation though RNA interference where an enzyme associated guide RNA target specific mRNA for selective destruction. Likewise, in eukaryotes the maintenance of telomeres involves copying of a RNA template that is a constituent part of a telomerase ribonucleoprotein enzyme.

Thus, this states that RNA world entity has many positive arguments to consider RNA as the evolutionary molecule, and most flexible molecule that kick-started the complex life.

The presence of RNA as a genetic material in many viruses and the primitive associationship between the RNA sequence/molecule of prokaryotes and eukaryotes further emphasizes on the possibility of the RNA world.