Question

Rosalind Franklin used X-Ray diffraction to study wet DNA. Her data were used by James Watson and Francis Crick to determine the structure of DNA. What did her data suggest about the structure of DNA?

1) The amount of A is equal to the amount of T and the amount of C is equal to the amount of G.
2) DNA is a helical structure that is not a single strand and consists of about 10 base pairs per complete turn.
3) DNA is a single strand.
4) adenine forms hydrogen bonds with thymine and guanine forms hydrogen bonds with cytosine

Answer 1

Rosalind Franklin's X-ray diffraction work was crucial in identifying DNA's structure as a double helix with approximately 10 base pairs per turn.

Step-by-step explanation:

Rosalind Franklin made significant contributions to the understanding of DNA structure through her meticulous work capturing X-ray diffraction images of DNA, which were instrumental in the eventual discovery of DNA's double helical structure by James Watson and Francis Crick. Her data suggested that DNA is a helical structure consisting of two strands (hence a double helix) with about 10 base pairs per turn. This information, combined with additional research such as Chargaff's rules asserting the pairing equality between adenine (A) and thymine (T), as well as between guanine (G) and cytosine (C), allowed Watson and Crick to propose a double helical structure where A pairs with T and G pairs with C via hydrogen bonding. Hence, the correct answer to the student's question is option 2.