1. Big Picture 🌍🧬

Scientists agree that RNA appeared before DNA and served as the very first genetic material. :contentReference[oaicite:0]{index=0} It didn’t just store information—it also sped up key reactions, acting like an enzyme. Because of this two-in-one role, researchers call the early stage of life the “RNA World.” :contentReference[oaicite:1]{index=1}

2. Why RNA Took the Lead 🚀

  • Versatility: Early life’s must-do jobs—metabolism, translation, splicing, and more—centred on RNA molecules. :contentReference[oaicite:2]{index=2}
  • Catalytic power: Some modern reactions still rely on ribozymes (RNA catalysts), proving that RNA once ran the show. :contentReference[oaicite:3]{index=3}
  • Message carrier: RNA passes genetic instructions quickly, making it perfect for information transfer. :contentReference[oaicite:4]{index=4}

3. The Downside of Being RNA 😅

As a catalyst, RNA reacts easily, which makes it chemically unstable. This instability pushed life to find a tougher alternative. :contentReference[oaicite:5]{index=5}

4. How DNA Took Over the Archive 📚

  • Chemical upgrades: DNA evolved from RNA, adding modifications that boost stability. :contentReference[oaicite:6]{index=6}
  • Double-helix shield: Two complementary strands let DNA spot and repair damage, protecting genetic data. :contentReference[oaicite:7]{index=7}
  • Long-term storage: Because DNA stays intact, living cells now trust it for safekeeping, while RNA handles rapid messaging. :contentReference[oaicite:8]{index=8}

5. Quick Recap ✨

RNA came first, pulling double duty as both code and catalyst. Its reactive nature opened the door for sturdier DNA, whose double-stranded design guards our genes today. :contentReference[oaicite:9]{index=9}

Important Concepts for NEET 🔑

  1. RNA World Hypothesis: Early life relied on RNA for both heredity and catalysis. :contentReference[oaicite:10]{index=10}
  2. Ribozymes: RNA molecules can act as enzymes—proof of RNA’s ancient catalytic role. :contentReference[oaicite:11]{index=11}
  3. Instability Drives Evolution: RNA’s reactivity led to the rise of more stable DNA. :contentReference[oaicite:12]{index=12}
  4. DNA’s Double-Strand Repair: Complementary strands enable error checking and repair. :contentReference[oaicite:13]{index=13}