Gene Editing and CRISPR: Medical and Ethical Dimensions

TOPIC CLASSIFICATION

Subject: Science & Technology Sub-area: Biotechnology Prelim PYQ Trend: Moderate (concept questions, Nobel Prize related) Mains Relevance: GS-3 (Science & Technology, Ethics)

EXAMINER REASONING

CRISPR-Cas9 won the Nobel Prize in Chemistry (2020), making it a high-probability UPSC topic. The examiner tests: (a) technical understanding - how CRISPR works, components (Cas9, guide RNA, PAM sequence); (b) applications - gene therapy, agriculture (GM crops), disease models; (c) ethical dimensions - germline editing (He Jiankui case), designer babies, eugenics concerns; (d) regulatory framework in India - GEAC, DBT guidelines. Expect comparative questions with other gene-editing tools (ZFN, TALEN) and ethical dilemma questions.

Core Concept

What is Gene Editing? Gene editing is a type of genetic engineering in which DNA is inserted, deleted, modified, or replaced in the genome of a living organism using engineered nucleases (molecular scissors).

CRISPR-Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats):

• Discovery: Emmanuelle Charpentier and Jennifer Doudna (Nobel Prize 2020)
• Components: Cas9 enzyme (cuts DNA) + guide RNA (gRNA - targets specific DNA sequence) + PAM sequence (protospacer adjacent motif - required for cutting)
• How It Works: gRNA guides Cas9 to target DNA → Cas9 cuts both strands → cell's natural repair...