140 Review Questions

4. If DNA of a particular species was analyzed and it was found that it contains 27 percent A, what would be the percentage of C?

1. 27 percent
2. 30 percent
3. 23 percent
4. 54 percent

5. The experiments by Hershey and Chase helped confirm that DNA was the hereditary material on the basis of the finding that:

1. radioactive phage were found in the pellet
2. radioactive cells were found in the supernatant
3. radioactive sulfur was found inside the cell
4. radioactive phosphorus was found in the cell

6. Bacterial transformation is a major concern in many medical settings. Why might health care providers be concerned?

1. Pathogenic bacteria could introduce disease-causing genes in non-pathogenic bacteria.
2. Antibiotic resistance genes could be introduced to new bacteria to create “superbugs.”
3. Bacteriophages could spread DNA encoding toxins to new bacteria.
4. All of the above.

7. DNA double helix does not have which of the following?

1. antiparallel configuration
2. complementary base pairing
3. major and minor grooves
4. uracil

8. In eukaryotes, what is the DNA wrapped around?

1. single-stranded binding proteins
2. sliding clamp
3. polymerase
4. histones

9. Meselson and Stahl’s experiments proved that DNA replicates by which mode?

1. conservative
2. semi-conservative
3. dispersive
4. none of the above

10. If the sequence of the 5′-3′ strand is AATGCTAC, then the complementary sequence has the following sequence:

1. 3′-AATGCTAC-5′
2. 3′-CATCGTAA-5′
3. 3′-TTACGATG-5′
4. 3′-GTAGCATT-5′

11. How did Meselson and Stahl support Watson and Crick’s double-helix model?

1. They demonstrated that each strand serves as a template for synthesizing a new strand of DNA.
2. They showed that the DNA strands break and recombine without losing genetic material.
3. They proved that DNA maintains a double-helix structure while undergoing semi-conservative replication.
4. They demonstrated that conservative replication maintains the complementary base pairing of each DNA helix.

12. Which of the following components is not involved during the formation of the replication fork?

1. single-strand binding proteins
2. helicase
3. origin of replication
4. ligase

13. Which of the following does the enzyme primase synthesize?

1. DNA primer
2. RNA primer
3. Okazaki fragments
4. phosphodiester linkage

14. In which direction does DNA replication take place?

1. 5′-3′
2. 3′-5′
3. 5′
4. 3′

15. A scientist randomly mutates the DNA of a bacterium. She then sequences the bacterium’s daughter cells, and finds that the daughters have many errors in their replicated DNA. The parent bacterium likely acquired a mutation in which enzyme?

1. DNA ligase
2. DNA pol II
3. Primase
4. DNA pol I

16. The ends of the linear chromosomes are maintained by

1. helicase
2. primase
3. DNA pol
4. telomerase

17. Which of the following is not a true statement comparing prokaryotic and eukaryotic DNA replication?

1. Both eukaryotic and prokaryotic DNA polymerases build off RNA primers made by primase.
2. Eukaryotic DNA replication requires multiple replication forks, while prokaryotic replication uses a single origin to rapidly replicate the entire genome.
3. DNA replication always occurs in the nucleus.
4. Eukaryotic DNA replication involves more polymerases than prokaryotic replication.

18. During proofreading, which of the following enzymes reads the DNA?

1. primase
2. topoisomerase
3. DNA pol
4. helicase

19. The initial mechanism for repairing nucleotide errors in DNA is ________.

1. mismatch repair
2. DNA polymerase proofreading
3. nucleotide excision repair
4. thymine dimers

20. A scientist creates fruit fly larvae with a mutation that eliminates the exonuclease function of DNA pol III. Which prediction about the mutational load in the adult fruit flies is most likely to be correct?

1. The adults with the DNA pol III mutation will have significantly more mutations than average.
2. The adults with the DNA pol III mutation will have slightly more mutations than average.
3. The adults with the DNA pol III mutation will have the same number of mutations as average.
4. The adults with the DNA pol III mutation will have fewer mutations than average.