CRISPR-Cas9 Explained 2026: Principle, Uses, MCQs for NEET PG

CRISPR-Cas9 Gene Editing Explained: Principle, Medical Applications, Latest 2025 Research + 15 MCQs

Last Updated: June 2026 | For: B.Sc, M.Sc, MBBS, PhD, CSIR NET, GATE, USMLE Aspirants

If you are a biology student, you have definitely heard "CRISPR" in the last 2 years. It’s the hottest topic in genetics, biotech, and medicine. Jennifer Doudna and Emmanuelle Charpentier won the 2020 Nobel Prize for this discovery. In 2025, FDA approved 3 new CRISPR-based therapies for sickle cell anemia and beta-thalassemia.

Why this topic is important for you: 1. CSIR NET Life Science Unit-8: 3-4 questions every year 2. USMLE Step 1: High-yield genetics topic 3. NEET PG: New pattern me clinical application based questions 4. PhD Interviews: Most asked research topic in 2025-26

1. What is CRISPR-Cas9? Simple Definition

CRISPR = Clustered Regularly Interspaced Short Palindromic Repeats
Cas9 = CRISPR-associated protein 9

In simple words: CRISPR-Cas9 is like "molecular scissors" that can cut DNA at a specific location. After cutting, scientists can delete, insert, or edit any gene. Think of it as "Find & Replace" for your DNA.

2. Principle of CRISPR-Cas9: How It Works? Step-by-Step

CRISPR system has 2 main components:

Component	Function	Simple Analogy
1. gRNA (Guide RNA)	Finds the exact DNA sequence to cut	Google Maps Address
2. Cas9 Protein	Cuts the DNA at that location	Scissor

Mechanism in 4 Steps:

1. Design gRNA: Scientists make a 20-nucleotide RNA that matches the target DNA sequence.
2. Bind: gRNA + Cas9 protein form a complex and search the DNA.
3. Cut: When gRNA finds 100% matching DNA, Cas9 makes a double-strand break.
4. Repair: Cell tries to repair the break. Scientists use this chance to delete or insert new gene.

Key Point for Exams: Cas9 recognizes a small sequence called PAM (Protospacer Adjacent Motif) - NGG. Without PAM, Cas9 will not cut even if gRNA matches. This is a favorite MCQ!

3. Applications of CRISPR-Cas9: Why It’s Revolutionary

A. Medical Applications - High CPC Keywords

Disease	CRISPR Application 2026 Update	Clinical Trial Stage
Sickle Cell Anemia	FDA approved "Casgevy" therapy in Dec 2023. 95% patients cured.	Approved
Beta-Thalassemia	Same therapy "Casgevy" works. $2.2 million per patient cost.	Approved
Cancer - CAR-T Therapy	CRISPR used to edit T-cells to kill cancer. 2025: Trials for solid tumors started.	Phase 2/3
HIV	Excision BioTherapeutics removing HIV DNA from human cells. First human trial 2024.	Phase 1

Treatment Cost 2026: FDA approved Casgevy therapy costs $2.2 million per patient, making it one of the most expensive gene therapies.

4. Latest CRISPR Research 2026: What's New?

1. Base Editing: New version that changes A to G without cutting DNA. Safer, less errors. 2025 trials for cholesterol control started.
2. Prime Editing: "Search and Replace" for DNA. Can fix 89% of known genetic diseases theoretically.
3. CRISPR Delivery: Biggest problem was "how to send Cas9 inside body". 2025: Lipid nanoparticles success in liver, lungs.

5. CRISPR-Cas9: 15 Most Important MCQs for CSIR NET, GATE, NEET PG, USMLE

1. CRISPR-Cas9 was originally discovered in:
   a) Virus b) Bacteria c) Yeast d) Humans
   Answer: b) Bacteria - It’s a bacterial immune system against phages
2. The PAM sequence required for SpCas9 is:
   a) NAG b) NGG c) NGA d) NTT
   Answer: b) NGG - Most important for NET
3. Which of the following is NOT an application of CRISPR?
   a) Gene knockout b) Gene knock-in c) DNA sequencing d) Gene activation
   Answer: c) DNA sequencing - CRISPR edits, doesn’t sequence
4. First FDA approved CRISPR therapy "Casgevy" is for:
   a) Cancer b) HIV c) Sickle cell anemia d) Diabetes
   Answer: c) Sickle cell anemia - Approved Dec 2023
5. The main risk of CRISPR therapy is:
   a) High cost b) Off-target mutations c) Slow process d) Only works in plants
   Answer: b) Off-target mutations - Biggest safety concern

Note: Full 15 MCQs with detailed explanation chahiye to comment karo "PDF".

6. Conclusion + Study Tips

CRISPR is not just a topic, it’s the future of medicine. For exams, focus on: Principle, PAM, gRNA, Applications, Ethical issues, Latest approvals. For PhD interviews, read 1-2 Nature papers from 2025 on base editing.

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Written by: IndiaBiologyNEET Team | Tags: CRISPR Cas9, Gene Editing, CSIR NET Unit 8, USMLE Genetics, NEET PG

Also Read: DNA Replication vs Transcription: 20 MCQs for CSIR NET