The Structure of DNA

Which of the following is a nucleotide found in DNA?

• adenine, phosphate group, thymine

• cytosine, phosphate group, guanine

• deoxyribose, phosphate group, polymerase

• deoxyribose, phosphate group, cytosine

Which of the following best describes Rosalind Franklin's contribution to our understanding of the structure of DNA?

• She created many models of DNA based on what was knows about its properties.

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

• She discovered the amounts of guanine and cytosine were almost exactly the same.

• She found that DNA was the transforming material using radioactive phosphorus and sulfur.

Which of the following statements correctly describes Chargaff's contribution to the study of DNA?

• Chargaff hypothesized that DNA was a double helix, but he did not produce the image that proved this fact.

• Chargaff's experiments conclusively proved that DNA was made of nucleotides, but he could not show that there are four types of nitrogenous bases.

• Chargaff showed that adenine and thymine were found in equal percentages in DNA, but he did not know this was because of base pairing.

• Chargaff's work proved that DNA could be made using radioactive nucleotides, but did not show that DNA could be transferred from one organism to another.

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

• Hershey and Chase

• Griffith

• Watson and Crick

• Franklin

Which of the following forms a base pair with thymine?

• deoxyribose

• adenine

• guanine

• cytosine

Watson and Crick discovered the two strands in DNA

• run in perpendicular directions.

• run in the same direction.

• run in opposite directions.

• run in random directions.

What type of bonds hold the base pairs together?

• hydrogen

• ionic

• covalent

• polar covalent

According to the base pair rules, which answer shows the correct pairings of the nitrogenous bases?

• adenine = guanine, thymine= cytosine (A=G, T=C)

• thymine = guanine, adenine= cytosine (T=G, A=C)

• phosphorus=adenine, cytosine=guanine (P=A, C=G)

• adenine=thymine, cytosine=guanine (A=T, C=G)