Milestones in Biology 2: Test Your Knowledge

Which technique did Rosalind Franklin use to examine the structure of DNA?
a. mass spectrometry

b. gel electrophoresis

c. x-ray diffraction

d. model building

e. all of the above

Which of the following statements about DNA structure is not true?
a. DNA is a double helix.

b. The phosphate groups are on the outside of the helix.

c. The two strands run in opposite orientations.

d. A pairs with A, T with T, C with C, and G with G.

e. The helix has a constant diameter along its length.

Describe the scientific contributions of Watson, Crick, Franklin, and Wilkins to the discovery of the structure of DNA.

How did differing amounts of water in the DNA crystals help explain the x-ray diffraction patterns?

Summarize the structure of a DNA double helix.