RNA World - The Genetic Material

RNA stands for Ribonucleic acid, it is one of the two most important nucleic acids in an organism, the other one being DNA (Deoxyribonucleic acid). Even though RNA serves as the genetic material in some organisms, DNA is considered to be the predominant genetic material in all organisms. Here we will discuss RNA world.

RNA World

According to the RNA world hypothesis, ribonucleic acid is the first genetic material where all genetic information was stored and first life arose from it. It is a self-replicating molecule. In simple words, RNA is the precursor to the every life form that exists today on the earth. It is believed that modern cells arose from them and every essential process that occurs in living organisms evolved around RNA. RNA world hypothesis was widely accepted by the scientific community.

RNA World

RNA’s was also considered as a catalyst for certain biochemical reactions in the primitive cells. the presence of 2-OH group made them more reactive and thus a suitable biocatalyst. However, this reactive nature made them labile to degradation and hence unstable. This instability gave a wide scope of mutation required for evolution. But being a hereditary material it should have been stable in both chemically and structurally.

Eventually, these unstable molecules have been replaced by more stable hereditary molecules. During this evolutionary period, DNA and protein molecules came into the picture. They replaced the role of RNA as the genetic material and structural component. RNA was a single-stranded hereditary molecule which stored and expressed genetic information. But their unstable and degrading nature led to the evolution of double-stranded DNA- genetic material which was more stable both chemically and structurally.

However, RNA is not completely eliminated. They still serve as genetic material in some organisms and they catalyze few essential biochemical reactions in the cells. Also, the complex machinery of protein synthesis from DNA is still proceeding through RNA.

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Practise This Question

Read the following statement and inferences, and select the correct option.

Statement: The core of the larger ribosomal subunit, where the catalysis of the peptidyl bond happens between one amino acid and the next, is made up entirely of rRNA.

Inference:

A.      rRNA is smaller than proteins and hence can fit in the smallest of crevices

B.      rRNA has catalytic capability and hence confers the name ribozyme to ribosome

C.      The proteins which make up ribosome do not have a significant role to play in its catalytic activity

Which of the inferences are true?