Question

write short notes on RNA World​

Answer 1

Explanation:

The RNA world hypothesis suggests that life on Earth began with a simple RNA molecule that could copy itself. The RNA world hypothesis suggests that life on Earth began with a simple RNA molecule that could copy itself without help from other molecules. DNA, RNA, and proteins are central to life on Earth.

Answer 2

Answer:

The RNA world is a hypothetical stage in the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins. The term also refers to the hypothesis that posits the existence of this stage.

A comparison of RNA (left) with DNA (right), showing the helices and nucleobases each employs

Alexander Rich first proposed the concept of the RNA world in 1962,[1] and Walter Gilbert coined the term in 1986.[2] Alternative chemical paths to life have been proposed,[3] and RNA-based life may not have been the first life to exist.[2][4] Even so, the evidence for an RNA world is strong enough that the hypothesis has gained wide acceptance.[1][5][6] The concurrent formation of all four RNA building blocks further strengthened the hypothesis.[7]

Like DNA, RNA can store and replicate genetic information; like protein enzymes, RNA enzymes (ribozymes) can catalyze (start or accelerate) chemical reactions that are critical for life.[8] One of the most critical components of cells, the ribosome, is composed primarily of RNA. Ribonucleotide moieties in many coenzymes, such as acetyl-CoA, NADH, FADH, and F420, may be surviving remnants of covalently bound coenzymes in an RNA world.[9]

Although RNA is fragile, some ancient RNAs may have evolved the ability to methylate other RNAs to protect them.[10]

If the RNA world existed, it was probably followed by an age characterized by the evolution of ribonucleoproteins (RNP world),[2] which in turn ushered in the era of DNA and longer proteins. DNA has better stability and durability than RNA; this may explain why it became the predominant information storage molecule.[11] Protein enzymes may have come to replace RNA-based ribozymes as biocatalysts because their greater abundance and diversity of monomers makes them more versatile. As some co-factors contain both nucleotide and amino-acid characteristics, it may be that amino acids, peptides and finally proteins initially were co-factors for ribozymes.[9]