Question

The scientist who developed a method for sequencing the DNA fragments was:

• A. Frederick Griffith
• B. Frederick Sanger
• C. George Gamow
• D. Har Gobind Khorana

Hint:

Key Milestones:
$\bullet$ Frederick Sanger: DNA sequencing (Chain termination method) & Protein sequencing.
$\bullet$ Griffith: Transformation experiment.
$\bullet$ Gamow: Triplet nature of genetic code.
$\bullet$ Khorana: Chemical synthesis of defined RNA homopolymers.

Answer 1

The Correct Option is B

Concept:
The development of biochemical methods for determining the exact sequence of nucleotide bases in DNA laid the foundation for modern genomics and genetic engineering.

Step 1: Historical Contributions of Frederick Sanger:
Frederick Sanger developed the dideoxy chain-termination technique, commonly known as the Sanger sequencing method.
This method uses 2',3'-dideoxynucleoside triphosphates (ddNTPs) that terminate DNA strand synthesis when incorporated by DNA polymerase.
Automated sequencing machines were subsequently designed based on Sanger's principles and were instrumental in completing the Human Genome Project (HGP).
Sanger also developed the method for sequencing amino acids in proteins (specifically insulin).

Step 2: Evaluating Other Scientists' Contributions:
- Frederick Griffith (1928): Discovered the 'Transforming Principle' using virulent and avirulent strains of Streptococcus pneumoniae in mice.
- George Gamow: A physicist who proposed that genetic code is a triplet code made up of three bases to specify 20 amino acids ($4^3 = 64$ codons).
- Har Gobind Khorana: Successfully synthesized defined poly-ribonucleotides and co-polymers to help decipher the triplet genetic code.

Step 3: Conclusion and Final Selection:
Thus, the scientist credited with developing the fundamental method for sequencing DNA fragments is Frederick Sanger.