What is Cas9 protein that is often mentioned in news?
- A.A molecular scissors used in targeted gene editing
- B.A biosensor used in the accurate detection of pathogens in patients
- C.A gene that makes plants pest-resistant
- D.A herbicidal substance synthesized in genetically modified crops
Correct answer
Explanation
The correct answer is A, A molecular scissors used in targeted gene editing. Cas9 is the enzyme in the CRISPR-Cas9 system that cuts DNA at a chosen spot, which is why it is called molecular scissors. The system comes from the natural defence of bacteria against viruses. In the laboratory, scientists pair Cas9 with a short guide RNA that matches the target gene; the guide leads Cas9 to that exact sequence, Cas9 cuts both strands of the DNA, and the cell's own repair machinery then disables the gene or inserts a corrected copy. Because it is cheap, fast and precise, it is used to study genes, develop crops and design treatments for inherited diseases such as sickle cell anaemia. Emmanuelle Charpentier and Jennifer Doudna won the 2020 Nobel Prize in Chemistry for developing it. Option B is wrong because Cas9 cuts DNA; it is not a sensor. Option C is wrong because Cas9 is a protein, not a gene, and pest resistance in Bt crops comes from the cry genes. Option D is wrong because Cas9 is not a herbicide. Exam tip: CRISPR-Cas9 = gene editing; Nobel Chemistry 2020.
Practice Questions
View allWhich one of the following is India's first indigenously designed and developed long-range subsonic cruise missile which can be deployed from multiple platforms?
- A.Astra
- B.Akash
- C.Nirbhay
- D.Shankhnaad
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Nirbhay is the long-range subsonic cruise missile designed and developed in India by the DRDO. Nirbhay was developed by DRDO's Aeronautical Development Establishment in Bengaluru.
Read the full explanation →"Million Minds Augmenting National Aspirations and Knowledge" (MANAK), a scheme under the flagship programme, Innovation in Science Pursuit for Inspired Research (INSPIRE), caters to :
- A.The college students studying in the undergraduate programme in the age group of 19 - 25 years.
- B.The research scholars in recognized research laboratories of national importance.
- C.The college teachers of the country.
- D.The school children studying in classes 6 - 10 in the age group of 10 - 15 years.
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INSPIRE-MANAK is the school-level part of INSPIRE. INSPIRE is run by the Department of Science and Technology to draw young talent into science.
Read the full explanation →Which one of the following statements is not correct?
- A.BrahMos is a supersonic cruise missile made by India and Russian Federation.
- B.The name BrahMos came from two rivers, Brahmaputra of India and Moskva of Russia.
- C.Indian military scientists were capable of integrating BrahMos cruise missile with Sukhoi-30 MKI fighter.
- D.Defence Research and Development Organization is the manufacturer of Sukhoi-30 MKI fighter.
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The Sukhoi-30 MKI is not made by DRDO; it was designed by Russia's Sukhoi bureau and is built in India under licence by Hindustan Aeronautics Limited (HAL) at Nashik.
Read the full explanation →'Tejas' is the name of which one of the following?
- A.Main battle tank
- B.Nuclear submarine
- C.Light combat aircraft
- D.Aircraft carrier
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Tejas is India's indigenous single-engine light combat aircraft built for the Indian Air Force. The Light Combat Aircraft programme was started in the 1980s to replace the ageing MiG-21 fleet.
Read the full explanation →Which one of the following is an indigenous assault rifle developed by DRDO?
- A.Heckler
- B.T91
- C.Tikka
- D.Ugram
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Ugram is a 7.62 mm assault rifle designed in India by DRDO for the armed forces and police. Ugram was developed by the Armament Research and Development Establishment (ARDE), Pune, a DRDO laboratory, together with a private Hyderabad firm, Dvipa Armour India, and it was unveiled in January 2024.
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