Choose the correct answer from the options given below :

1. (A)–(II); (B)–(III); (C)–(IV); (D)–(I)
2. (A)–(IV); (B)–(III); (C)–(I); (D)–(II)
3. (A)–(I); (B)–(II); (C)–(IV); (D)–(III)
4. (A)–(II); (B)–(IV); (C)–(I); (D)–(III)

   Maxam-Gilbert to Khorana: Correct Matching of DNA Pioneers’ Contributions

   Maxam-Gilbert and others revolutionized molecular biology through key DNA advancements. This article reveals the correct match for this classic exam question.

   Correct Answer

   The right option is (A)–(II); (B)–(IV); (C)–(I); (D)–(III).
   Maxam-Gilbert developed the chemical DNA sequencing method in 1977. Stanley Cohen pioneered DNA cloning via recombinant techniques. Arthur Kornberg isolated DNA polymerase I from E. coli in 1956. Har Gobind Khorana elucidated the complete genetic code using synthetic polynucleotides.

   Scientists’ Contributions

   Maxam-Gilbert (A) – DNA Sequencing (II)

   Allan Maxam and Walter Gilbert created the first widely used DNA sequencing technique, relying on chemical cleavage at specific bases. This method sequenced DNA fragments up to thousands of bases before Sanger’s dideoxy approach dominated. Gilbert shared the 1980 Nobel Prize for this breakthrough.

   Stanley Cohen (B) – DNA Cloning (IV)

   Stanley Cohen, with Herbert Boyer, invented recombinant DNA technology in 1973, enabling gene cloning by inserting foreign DNA into plasmids. This foundational work birthed genetic engineering and biotech applications.

   Kornberg (C) – DNA Polymerase Isolation (I)

   Arthur Kornberg purified DNA polymerase I from E. coli, proving its role in DNA replication and earning the 1959 Nobel Prize. His enzyme was key for in vitro DNA synthesis studies.​

   Har Gobind Khorana (D) – Genetic Code (III)

   Har Gobind Khorana synthesized artificial genes to decode all 64 codons, confirming the genetic code’s universality. He shared the 1968 Nobel Prize with Nirenberg and Holley for this achievement.​

   All Options Explained

   Option	Matching	Correct?	Why?
   1. (A)–(II); (B)–(III); (C)–(IV); (D)–(I)	Maxam-Gilbert: Sequencing; Cohen: Genetic code; Kornberg: Cloning; Khorana: Polymerase	No	Cohen did cloning, not code; mismatches historical roles .
   2. (A)–(IV); (B)–(III); (C)–(I); (D)–(II)	Maxam-Gilbert: Cloning; Cohen: Genetic code; Kornberg: Polymerase; Khorana: Sequencing	No	Maxam-Gilbert focused on sequencing, not cloning ​.
   3. (A)–(I); (B)–(II); (C)–(IV); (D)–(III)	Maxam-Gilbert: Polymerase; Cohen: Sequencing; Kornberg: Cloning; Khorana: Genetic code	No	Polymerase links to Kornberg; Cohen to cloning ​.
   4. (A)–(II); (B)–(IV); (C)–(I); (D)–(III)	Maxam-Gilbert: Sequencing; Cohen: Cloning; Kornberg: Polymerase; Khorana: Genetic code	Yes	Matches verified contributions across sources .