Chapter 12

12.1 Identifying the Substance of Genes 12.2 The Structure of DNA 12.3 DNA Replication More DNA

1. Which bacteria killed the mice in Griffin’s transformation experiment?

A live, harmless bacteria and heat-killed, harmful bacteria

2. Griffith called the process he observed transformation because

C the harmless bacteria had been transformed.

3. What did Avery conclude caused transformation?

A DNA was the transforming factor.

4. What happened when Griffith injected mice with the harmless, R-strain bacteria alone?

B The mouse lived.

5. What would have happened if Avery had added an enzyme that digested all the nucleic acids to the mixture of heat-killed bacteria, added the mixture to harmless bacteria, and injected the mixture into mice?

B The harmless bacteria would not have been transformed, and the mice would have lived.

6. What property of DNA does bacterial transformation illustrate?

B Bacterial DNA can move into another bacteria and function.

7. In Griffith’s bacterial transformation experiments,

A harmless bacteria change into harmful bacteria.

8. What is inside a bacteriophage?

B nucleic acid

9. What do bacteriophages infect?

D bacteria.

10. Why did Hershey and Chase label the viral DNA with radioactive phosphorous and not radioactive sulfur?

A DNA contains phosphorus and no sulfur.

11. Which part of the bacteriophage in Figure 12–1 contains genetic material? Figure 12 – 1

BBBB

12. What stores information in a cell?

D DNA

13. What happens when a piece of DNA is missing?

C Genetic information is lost.

14. In what way is DNA like a book?

B DNA has stored information, that can be copied and passed on.

15. In which cells is the accurate transmission of information most important?

C sex cells

16. Figure 12–2 shows the structure of Figure 12 – 2

A a DNA molecule.

17. Which of the following is a nucleotide found in DNA?

D deoxyribose + phosphate group + cytosine

18. Because of base pairing in DNA, the percentage of

B thymine molecules in DNA is about equal to the percentage of adenine molecules

19. The table in Figure 12–3 shows the results of measuring the percentages of the four bases in the DNA of several different organisms. Some of the values are missing from the table. Based on Chargaff’s rule, the percentages of guanine bases in chicken DNA should be around Nitrogenous Bases (%) AGTC Human Chicken Bacterium (S. lutea) Figure 12 – 3

C 21.5%

20. Based on Chargaff’s rule, the percentage of cytosine in the DNA of the bacterium, S. Lutea in Figure 12–3, should be around Nitrogenous Bases (%) AGTC Human Chicken Bacterium (S. lutea) Figure 12 – 3

C 36.6%.

21. What structural problem prevents adenine from pairing with guanine?

D The bases are both long.

22. Which two bases pair together in DNA?

D cytosine and guanine

23. Avery’s experiments showed that bacteria are transformed by

B DNA.

24. What did Griffith observe when he injected a mixture of heat-killed, disease-causing bacteria and live harmless bacteria into mice?

B The mice developed pneumonia.

25. What would Hershey and Chase have concluded if both radioactive 32 P and 35 S were found in the bacteria in their experiment?

D Both the virus’s protein coat and its DNA were injected into the bacteria.

26. Avery’s experiment worked because bacteriophages and bacteria share which component?

C DNA

27. In the Hershey-Chase experiment, what happened to the bacteria that had been infected by viruses that had radioactive DNA, and to the bacteria that had been infected with viruses that had been marked with radioactive proteins?

A The bacteria infected with viruses that had radioactive DNA had become radioactive. The bacteria that had been infected with viruses marked with radioactive proteins were not radioactive.

28. Which scientist made x-ray diffraction photos of DNA?

A Franklin

29. What is the chronological order of the important discoveries in the structure of DNA?

D Chargaff’s ratios of nucleotides  Franklin makes an X-ray diffraction photo of DNA  Watson and Crick identify the double helix

30. The table in Figure 12–4 shows the percentages of bases in a DNA sample. How much Thymine should you expect to find in the sample? Figure 12 – 4

A 22%

31. What would happen to the percentage of G in Figure 12–4 if the percentage of A rose to 25%? Figure 12 – 4

B G would drop to 25%

32. Which of the following forms a base pair with thymine?

B adenine

33. What did Rosalind Franklin contribute to the effort to identify the structure of DNA?

D x-ray diffraction photos of the DNA molecule

34. Watson and Crick discovered the two strands in DNA

C run in opposite directions.

35. DNA replication results in two DNA molecules,

C each with one new strand and one original strand.

36. During DNA replication, a DNA strand that has the bases CTAGGT produces a strand with the bases

B GATCCA.

37. After DNA replication in eukaryotes, the

D nucleosomes become more tightly packed.

38. Which of the following include all the others?

C chromosomes

39. In Figure 12–5, what nucleotide is going to be added at point 1, opposite from thymine? Figure 12 – 5

A adenine

40. In Figure 12–5, what is adding base pairs to the strand? Figure 12 – 5

C DNA polymerase

41. In eukaryotes, DNA

A is located in the nucleus.

42. Which would be greater in a eukaryote than in a prokaryote?

C The number of replication forks on a strand of DNA.

43What binds to the prokaryotic chromosome to start DNA replication?

B regulatory proteins

44In both prokaryotes and eukaryotes, how many copies of the chromosome are left after replication?

B2B2

45Eukaryotic cells can have up to how many times more DNA than prokaryotic cells?

C 1,000