Self-Replicating RNA Discovery

Why in News?

Recently, scientists have reported RNA may have been Earth’s first genetic material.

• Key Findings – Scientists have discovered a very small RNA molecule called QT45 that can copy itself.
• This is the first clear evidence of a simple RNA molecule that can self-replicate.
• It strengthens the idea that RNA may have been the first genetic material on Earth, but it does not prove it.
• Experiments on Life’s Origin – In 1953, scientists (in the Miller-Urey experiment) recreated early Earth conditions in a lab.
• They showed that amino acids (building blocks of proteins) could form naturally. However, they did not find DNA or RNA in it.
• This meant that forming proteins was only part of the story of how life began.
• Core Issue – Life needs genetic material (DNA or RNA) to store information and a way to copy it to make new life.
• Modern cells use proteins to copy DNA or RNA, but DNA and RNA are needed to make those proteins, creating a “chicken-and-egg” problem for the origin of life.
• RNA’s Special Role – In the 1980s, scientists found that RNA, being a single molecule, could both store information and carry out chemical reactions.
  • It stores genetic instructions and also acts like a basic enzyme, doing jobs needed for life on its own.
• Early Life – This suggested that early life may have depended only on RNA, before proteins evolved.
• Limitations – Earlier lab-made RNA was large and complex, and it could help copy others but not itself.
• Development of QT45 – The researchers selected rare RNA sequences from large pools and improved them step by step until QT45 was developed.
• QT45 is only 45 nucleotides long and can copy its own genetic information.

Nucleotides are the tiny building blocks that make up DNA and RNA.

• QT45 Replication – QT45 copies itself by three-nucleotide building blocks.  That is the joining of small three-letter pieces.
  • First, it makes a matching copy and then uses that copy to rebuild the original version.
• Slow Replication – The copying is very slow and needs special conditions — it can take weeks, while modern cells do it in seconds.
• But early Earth had millions of years, so even slow copying could have worked.

Quick facts

• DNA – Stores and replicates genetic information as a long, stable double-stranded molecule, acting as the blueprint for life.
• RNA – It is shorter, single-stranded, and carries genetic instructions from DNA to build proteins, while also being chemically more reactive.

Reference

TH | Self-Replicating RNA Discovery