Question

Who proposed the double helix structure of DNA and when?

• A. Watson and Crick, 1953
• B. Hershey and Chase, 1952
• C. Avery, McCarty and MacLeod, 1944
• D. Griffith, 1928

Answer 1

The correct option is A

Watson and Crick, 1953

The correct option is A.

Explanation of correct option:

1. James D.Watson and Francis Crick,1953, proposed the double helix model.
2. DNA(Deoxyribonucleic Acid) is defined as a molecule that has genetic information and which controls the characteristics of all organisms and passes the genetic information to further generations.
3. Rosalind Franklin's X-ray crystallography did a great help to Watson and Crick in discovering the double helix structure.
4. They described the double helix model as two twisted ladders.
5. The two helices were held together by hydrogen bonds and have a backbone of sugar-phosphate phase in each strand and nitrogenous bases in between
6. There are four types of bases, A(Adenine), G(Guanine), T(Thymine), and C(Cytosine).
7. Watson, Crick, and Maurice Willikins also received a Noble Prize in Physiology or Medicine in 1962 for their discovery of the molecular structure of DNA.

Explanation of incorrect options:

Option B:

1. Alfred Hershey and Martha Chase,1952 confirmed that DNA is the genetic material and not the protein.

Option C:

1. Avery, McCarty, and MacLeod expanded the work of Griffith and revealed that the transforming substance is DNA.
2. They inserted two different strains of Streptococcus pneumonia into mice and found that bacteria were transformed.

Option D:

1. Frederick Griffith,1928, was working on a vaccine for pneumonia and accidentally discovered the transformation.
2. He proposed that genetic material can be transformed and called it as ‘Transforming Principle’.

Final answer: Watson and Crick, 1953 proposed the double helix structure of DNA