Relevance: GS III (Science & Tech – Biology) | Source: The Hindu

1. The Discovery (The News)

Scientists have found that the genetic material (RNA) of bacteria can stay active in drinking water even after the bacteria have been killed by disinfectants.

This is possible because the RNA is specially protected. By studying these surviving genetic “messages,” scientists can learn how bacteria try to defend themselves, helping us build much better water purification systems.

2. Know the RNA 

Ribonucleic acid (RNA) is a vital, typically single-stranded nucleic acid molecule found in all living cells and some viruses, functioning primarily in protein synthesis and gene regulation.

While exRNA lives outside, remember the three types that work inside the cell:

RNA Type	Role
mRNA (Messenger)	The Blueprint: Copies instructions from DNA. (Used in COVID-19 vaccines).
tRNA (Transfer)	The Delivery Truck: Brings raw materials (amino acids) to the factory.
rRNA (Ribosomal)	The Factory Machine: Actually builds the protein.

3. Breaking the Myth: What is exRNA?

• The Old Belief: For decades, we thought RNA could only survive inside a living cell. If it leaked out, it would be instantly destroyed by the environment.
• The New Reality: We now know cells intentionally pack RNA into tiny, protective bubbles (called vesicles) and release them outside into blood, saliva, and water.
• Because this RNA floats freely outside the cell, it is called extracellular RNA (exRNA).

4. How the Body Uses It 

Why do cells throw RNA out? They use it like a “Biological WhatsApp”:

• The Messenger: One cell releases exRNA to send genetic instructions to another cell located far away in the body.
• Healing: When the receiving cell reads the message, it changes its behavior. This is how our body coordinates immune responses and heals wounds.
• Cancer Risks: Cancer cells hijack this system. They send out “fake” exRNA messages to trick healthy cells into helping a tumor grow and spread.

5. The Medical Revolution: ‘Liquid Biopsy’

Because exRNA floats in our blood and spit, it has changed how we find diseases:

• Old Way: Testing for cancer required a painful surgery to cut out a piece of flesh (Surgical Biopsy).
• New Way: Today, doctors can just take a simple blood or saliva sample. By reading the exRNA patterns, they can catch cancer or heart disease very early without any pain. This is called a Liquid Biopsy.

The “UPSC Trap”

• The “Inside Only” Trap: UPSC may claim RNA is strictly confined inside a cell. Incorrect. exRNA travels freely outside in bodily fluids.
• The “Surgery” Trap: A statement might say a Liquid Biopsy requires surgery. Incorrect. It is a non-invasive blood or saliva test.

UPSC Value Box

Key Term	Simple Meaning
exRNA	Extracellular RNA; genetic material used for communication outside of cells.
Liquid Biopsy	A pain-free medical test using bodily fluids to detect diseases early, avoiding surgery.

With reference to Ribonucleic Acid (RNA) and modern medicine, consider the following statements:

1. Extracellular RNA (exRNA) can survive outside the cell because it is enclosed in tiny protective molecular bubbles.
2. A ‘Liquid Biopsy’ involves testing bodily fluids like blood or saliva to detect diseases early without surgery.
3. Inside a human cell, Messenger RNA (mRNA) acts as the delivery truck that brings raw amino acids to build proteins.

Which of the statements given above is/are correct?

(a) 1 and 2 only

(b) 1 and 3 only

(c) 3 only

(d) 1, 2 and 3

Correct Answer: (a)