Rosalind Franklin's X-ray crystallography data suggested DNA is double stranded and has a uniform diameter. These observations can be used to rule out base pairing between two of the same nucleotide because ________.
A) the antiparallel orientation of strands would result in one of the pair being upside down
B) identical nucleotides would not have the appropriate number of hydrogen bonding sites to pair
C) an A-A pair is wider than a C-C pair
D) thymine dimers are removed by excision repair

Question

Quizplus · Accepted Answer

The uniform diameter of the DNA helix suggests that base pairs must consist of one purine and one pyrimidine, as purine-purine pairs (like A-A) would be too wide and pyrimidine-pyrimidine pairs (like C-C) would be too narrow.

Rosalind Franklin's X-Ray Crystallography Data Suggested DNA Is Double Stranded