Q.The first genetic material could be:
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Start your 14-day free trial to unlock the full solution →The first genetic material on Earth was most likely RNA, not DNA, because RNA can both store information and catalyse chemical reactions — a dual role essential before enzymes and DNA replication machinery existed.
The question of what served as the very first genetic material is not just a trivia point — it gets to the heart of how life itself began. When we think of genetic material today, DNA immediately comes to mind. It is the stable, long-term storehouse of hereditary information in all cellular life. But DNA is a complex molecule. It cannot replicate itself without the help of many proteins (enzymes like DNA polymerase). And those proteins themselves are made using instructions carried by another molecule — RNA. This creates a chicken-and-egg problem: which came first, the information-storing molecule or the protein-making machinery?
The NCERT textbook addresses this puzzle directly. It points out that RNA is a far more plausible candidate for the first genetic material than DNA, protein, or carbohydrate. Here is why.
Proteins and carbohydrates, while essential for life, are not good at storing and transmitting hereditary information in a stable, replicable way. Proteins have immense structural and catalytic variety, but they do not have a simple, template-based copying mechanism. Carbohydrates are primarily structural or energy-storage molecules. Neither fits the role of a self-replicating information carrier.
DNA, on the other hand, is an excellent information store — its double-helix structure and base-pairing rules make replication accurate. But DNA is chemically inert. It cannot catalyse its own replication or any other reaction. For DNA to function as genetic material, a whole suite of protein enzymes must already exist to copy it, repair it, and read it. That is a huge evolutionary hurdle.
This is why the idea of an "RNA world" is so compelling. RNA is the only molecule that can act as both a carrier of genetic information (like DNA) and a catalyst (like a protein enzyme). Such catalytic RNAs are called ribozymes, and their existence was a landmark discovery.
RNA can fold into complex three-dimensional shapes, allowing it to catalyse reactions — including the formation of new RNA strands. This means that in a primordial soup, RNA molecules could have replicated themselves without needing any protein enzymes. They could store information in their sequence of bases and also speed up the chemical reactions needed to copy that sequence. This dual ability makes RNA the most logical candidate for the first genetic material. …
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