13.2 Structure of DNA

The observation that [A] = [T] and [G] = [C] became known as one of …………

• A. Chargaff’s rules

• B. Avery’s rules.

• C. Franklin’s rules

• D. Griffith’s rules

Which scientist/s figured out that the shape of a DNA molecule is a double helix?

• a. Hershey and Chase

• b. Griffith

• c. Watson and Crick

• d. Avery

Which of the following best describes Rosalind Franklin’s contribution to our understanding

of the structure of DNA?

• a. She created many models of DNA based on what was known about its properties and

  eventually figured out that the structure of DNA is a double helix.

• b. She purified large amounts of DNA, stretched the fibers so the strands were parallel,

  and used an X-ray beam to produce an image of the molecule.

• c. She isolated DNA from many different organisms and discovered that in every

  sample, the amount of guanine was almost exactly equal to the amount of cytosine.

• d. She used radioactive phosphorus and sulfur to produce radioactive viruses, then

  allowed these viruses to infect bacteria. She found that DNA was the transforming

  material.

Watson and Crick discovered that the two strands in DNA ----

• A. run in perpendicular directions

• B. run in the same direction.

• C. run in opposite directions.

• D. run in random directions.

Guanine (G) has three hydrogen bonds with Cytosine (C

• True

• False

-- are weak bonds that hold the two strands of DNA together but also

allow the DNA to separate and replicate.

Watson and Crick discovered that the two strands in DNA run in ------ directions.

DNA is a nucleic acid made up of nucleotides joined into long strands or chains by -----------

bonds.

DNA is a nucleic acid made up of ------- joined into long strands or chains by

covalent bonds.