‘RNA interference (RNAi)’ technology has gained popularity in the last few years. Why? 1. It is used in developing gene silencing therapies. 2. It can be used in developing therapies for the treatment of cancer. 3. It can be used to develop hormone replacement therapies. 4. It can be used to produce crop plants that are resistant to viral pathogens. Select the correct answer using the code given below.
Contents17
- A1, 2 and 4
- B2 and 3
- C1 and 3
- D1 and 4 only
Show answer
Answer: (A) 1, 2 and 4
The correct answer is (A) — 1, 2 and 4.
RNA interference (RNAi) is a natural process that silences (switches off) specific genes.
Statement 1 is correct — RNAi is used in gene silencing therapies.
Statement 2 is correct — it can treat cancers by silencing genes that help tumours grow.
Statement 4 is correct — RNAi can make crops resistant to viruses by silencing viral genes.
Statement 3 is wrong — RNAi works by blocking gene expression, not by replacing hormones.
Tip: RNAi = gene silencing tool.
It turns genes OFF, so it cannot replace hormones (which need genes turned ON).
RNAi is a gene silencing technology that switches off specific genes, making it useful for cancer therapy, antiviral crop development, and therapeutic gene silencing.
Around 2018-2019, several RNAi-based drugs received regulatory approvals and clinical trial successes, making it a hot current affairs topic in biotechnology.
The trap is statement 3 - RNAi silences genes but hormone replacement requires active hormone production, not gene silencing.
RNA Interference (RNAi) Mechanism
Science And Technology RNA interference RNAi gene silencing
RNA Interference (RNAi): Mechanism & Gene Silencing Process
RNAi is a natural cellular process that silences specific genes by blocking their expression
Works through small RNA molecules (siRNA/miRNA) that bind to target mRNA
Key principle: RNAi turns genes OFF, it cannot turn them ON or replace missing products
Discovered in C. elegans (nematode worms), leading to 2006 Nobel Prize
What is RNAi
RNA interference (RNAi) is a natural cellular defense mechanism that silences specific genes by preventing their mRNA from being translated into proteins. Think of it as a molecular 'OFF switch' that blocks gene expression without altering the DNA itself.
RNAi Process Steps
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Double-stranded RNA enters cell**
Long dsRNA or introduced siRNA`"]
s2["`**Dicer enzyme cuts dsRNA**
Produces small interfering RNA (siRNA) fragments`"]
s3["`**RISC complex loads siRNA**
RNA-induced silencing complex binds one strand`"]
s4["`**Target mRNA recognition**
siRNA guides RISC to complementary mRNA`"]
s5["`**mRNA degradation**
Target mRNA is cleaved and destroyed`"]
s6["`**Gene silencing achieved**
No protein produced from silenced gene`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5
s5 --> s6RNAi Pathway Diagram
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Trap: RNAi silences genes (turns OFF) — it cannot replace hormones or produce new proteins
Trap: RNAi works on mRNA level, not DNA — the gene sequence remains unchanged
Common error: Confusing RNAi with gene therapy — RNAi blocks expression, gene therapy adds/fixes genes
RNAi Therapeutic Applications
Science And Technology gene silencing therapies treatment of cancer
RNAi in Medicine: Gene Silencing Therapies & Cancer Treatment
RNAi enables targeted gene silencing therapies for genetic diseases
Cancer treatment: silences oncogenes and genes that help tumors grow
Cannot replace hormones — RNAi only turns genes OFF, doesn't produce new molecules
First RNAi drug Patisiran approved by FDA in 2018 for rare genetic disease
Medical Applications
RNAi offers precise therapeutic targeting by silencing disease-causing genes. Unlike traditional drugs that block proteins after they're made, RNAi prevents harmful proteins from being produced in the first place.
RNAi Medical Applications
Application | How RNAi Helps | Example Targets | Status |
|---|---|---|---|
Gene Silencing Therapies | Turn off disease-causing genes | Huntingtin gene in Huntington's disease | Clinical trials ongoing |
Cancer Treatment | Silence oncogenes & tumor-promoting genes | BCR-ABL fusion gene, p53 pathway | Research & early trials |
Viral Infections | Block viral gene expression | Hepatitis B, HIV genes | Experimental stage |
Genetic Disorders | Reduce toxic protein production | Transthyretin in amyloidosis | Patisiran approved |
Why NOT Hormone Replacement
RNAi mechanism only destroys existing mRNA — cannot create new hormones or proteins
Hormone replacement therapy requires adding missing hormones, not silencing genes
RNAi is a loss-of-function tool, while hormone therapy needs gain-of-function
Example: Insulin replacement needs insulin production, but RNAi would block insulin genes
Statement 3 trap: RNAi cannot replace hormones — it only silences, never adds or produces
Key distinction: Gene silencing ≠ Gene replacement ≠ Protein replacement
Cancer mechanism: RNAi blocks tumor-promoting genes, not by adding anti-cancer proteins
RNAi in Agriculture
Science And Technology crop plants resistant to viral pathogens
RNAi in Agriculture: Virus-Resistant Crops & Plant Protection
RNAi creates virus-resistant crops by silencing viral genes inside infected plants
Mechanism: Plant produces siRNA that targets viral mRNA for destruction
Advantage: Highly specific — targets only viral genes, not plant genes
Also used against insect pests and fungal pathogens in crops
Agricultural Revolution
RNAi technology enables crops to defend themselves against pathogens by producing targeted RNA molecules that silence essential genes in viruses, insects, or fungi. This creates built-in resistance without external pesticide applications.
RNAi Agricultural Applications
Target | RNAi Strategy | Crop Examples | Commercial Status |
|---|---|---|---|
Viral Pathogens | Silence viral replication genes | Papaya (ringspot virus), Beans | Some commercialized |
Insect Pests | Target essential insect genes | Corn (corn rootworm), Cotton | Field trials ongoing |
Fungal Diseases | Block fungal growth genes | Wheat (rust resistance) | Research stage |
Improved Traits | Silence plant genes for better quality | Low-lignin trees, improved nutrition | Development phase |
Virus Resistance Mechanism
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Transgenic plant created**
Plant engineered to produce viral-specific dsRNA`"]
s2["`**Virus infects plant**
Viral RNA enters plant cells`"]
s3["`**Plant RNAi activated**
Plant Dicer processes dsRNA into siRNA`"]
s4["`**Viral mRNA targeted**
siRNA guides RISC to viral mRNA`"]
s5["`**Viral genes silenced**
Virus cannot replicate effectively`"]
s6["`**Plant survives infection**
Crop remains healthy and productive`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5
s5 --> s6Advantages Over Traditional Methods
Specificity: Targets only pathogen genes, leaving beneficial organisms unharmed
Sustainability: Reduces need for chemical pesticides and fungicides
Durability: Multiple viral genes can be targeted simultaneously to prevent resistance
Environmental safety: RNA molecules degrade naturally, no persistent residues
Statement 4 is correct: RNAi can create virus-resistant crops by silencing viral genes
Key mechanism: Plant silences viral genes, not its own resistance genes
Don't confuse: RNAi crop protection vs. traditional genetic modification for herbicide resistance
Gene Regulation Mechanisms
Science And Technology
Gene Regulation: Controlling When & How Genes Are Expressed
Gene regulation controls when, where, and how much protein is made from each gene
RNAi is post-transcriptional regulation — acts after DNA is transcribed into mRNA
Cells use multiple regulation levels: transcriptional, post-transcriptional, and post-translational
Why Regulation Matters
Every human cell contains the same DNA, but different cell types (muscle, brain, liver) express different genes. Gene regulation is the cellular control system that determines which genes are active and which are silenced.
Levels of Gene Control
Regulation Level | Where It Acts | Mechanism Examples | RNAi Fits Here |
|---|---|---|---|
Transcriptional | DNA → mRNA | Promoters, enhancers, transcription factors | No |
Post-transcriptional | mRNA processing | RNAi, miRNA, alternative splicing | Yes - RNAi |
Translational | mRNA → Protein | Ribosome binding, protein synthesis control | No |
Post-translational | Protein modification | Phosphorylation, protein degradation | No |
Gene Regulation Strategies
# Gene Regulation
## Turning ON
- Activators
- Enhancers
- Hormone signals
- Growth factors
## Turning OFF
- **RNAi/miRNA**
- Repressors
- Silencers
- Chromatin modification
## Fine-tuning
- Alternative splicing
- Feedback loops
- Tissue-specific expressionRNAi position: Acts at post-transcriptional level — after mRNA is made but before protein
Key insight: RNAi is nature's way to fine-tune gene expression without changing DNA
Comparison trap: RNAi ≠ transcriptional control — it doesn't stop mRNA production, it destroys mRNA after it's made