Question

Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA?

A) the diameter of the helix
B) the rate of replication
C) the sequence of nucleotides
D) the bond angles of the subunits
E) the frequency of A vs. T nucleotides
E) It cannot be determined from the information provided.

Answer 1

A) the diameter of the helix

Step-by-step explanation:

This is was measured during the 3D structure of DNA proposed by James Waston and Francis Crick in 1953. The x-ray diffraction showed crossed shape of the X-ray films.The DNA appeared as two double strands structure.

The diameter of the DNA double helix is 20 Armstrong.

This diameter is constant because of the complementary pairing of bases.( purines with pyrimidines)